Yellow-Brown Loams
SOIL GROUPS OF NEW ZEALAND
Part 6 YELLOW-BROWN LOAMS
New Zealand Society of Soil Science 1982 SOIL GROUPS OF NEW ZEALAND
PART 6
YELLOW-BROWN LOAMS Edited by V.E. Neall
NEW ZEALAND SOCIETY OF SOIL SCIENCE 1982
. ' Bibliographic Reference: Neall, V.E. (Ed.) 1982: Soil Groups of New Zealand. Part 6, Yellow-brown loams. New Zealand Society of Soil Science, Wellington, New Zealand. 114p. PREFACE
Typing:. N.C. McLean, T.J. Roach The yellow-brown loams are to the dairy industry in the North Island what the Draughtmg: C.B. l>owell clover plant is to New Zealand's pastoral farming. Today, these soils also form the basis of our kiwifruit industry in the Bay of Plenty and of a host of new horticultural enterprises in addition to traditional market gardening uses, such as in south Auckland and Ohakune. Yellow-brown loams occupy about 1.5 million ha or about 15% of the North Island. They are one of the major natural resources of New Zealand and increasingly they will become a cornerstone of our food production industry and export earnings.
In this, the sixth volume of Soil Groups of New Zealand, the New Zealand Society of Soil Science has attempted to draw attention to the uniqueness of the yellow-brown loams and the special properties which they display. This volume comes at a time when global interest in such groups of soils is widespread and This volume has been compiled from both published readily complements the recently published book "Soils with Variable Charge", and unpublished information. Authors must be prepared for the International Conference held in New Zealand in February, 1981, consulted before papers are cited in other on this subject. publications. The Society is grateful to Dr Vince Neall for editing this very useful and timely volume.
J.K. Syers (President N .Z. Society of Soil Science) 18 March, 1982
P.D. HASSELBERG. GOVERNMENT PRINTER, WELLINGTON, NEW ZEALAND-1982 CONTENTS
Page 1 DEFINITION AND CLASSIFICATION ...... 7 Yellow-brown loams-definition and classification J.D. Cowie ...... 7 Classification of yellow-brown loams, intergrades and composites according to U.S. Soil Taxonomy (1975) and the 1978 Andisol proposals V.E. Neall, G.E. Orbell ...... 9 Classification-FAO/Unesco R.B. Miller ...... 11 2 SOIL STRATIGRAPHY STUDIES ...... 12 Parent materials of yellow-brown loams in the Waikato-Coromandel district H.S. Gibbs, D.J. Lowe, A. G. Hogg ...... 12 Soil stratigraphy of Kereone, Ohaupo and Mairoa soils in the Waikato and Te Kuiti districts R.L. Parfitt, S.M. Robertson, G.E. Orbell ...... 13 Elucidation of the Stratford Shower, Taranaki AM. Geddes, V.E. Neall ...... 16 3 DISTRIBUTION AND DESCRIPTION ...... 23 Early surveys of the yellow-brown loams 1939-1954 W.A. Pullar ...... 23 Yellow-brown loams of the Waikato region G.E. Orbell ...... 25 Yellow-brown loams in the South Auckland area B.R. Purdie ...... 29 Yellow-brown loams in the Bay of Plenty, Poverty Bay-East Coast and King Country districts W. C. Rijkse 33 Yellow-brown loams of Taranaki V.E. Neall...... 34 Yellow-brown loams of the Wanganui Region R.H. Wilde ...... 36 The Southland yellow-brown loams J. G. Bruce ...... 37 4 YELLOW-BROWNLOAMINTERGRADESANDCOMPOSITES ...... 41 Yellow-brown loam composites and intergrades in the King Country W. C. Rijkse ...... 41 The boundary between yellow-brown loams and yellow-brown earths; an example from the Dannevirke area, southern Hawke's Bay B.R. Purdie ...... 43 Yellow-brown loam to yellow-brown earth intergrades in Southland J. G. Bruce ...... 45 5 SOIL MINERALOGY ...... 47 Sand mineralogy of North Island yellow-brown loams R.B. Stewart ...... 47 The clay mineralogy of yellow-brown loam soils R.L. Parfitt, M. Russell, J.H. Kirkman ...... 48 6 SOIL PHYSICAL PROPERTIES ...... 54 Physical properties of yellow-brown loams M. W. Gradwell ...... 54 Factors affecting 15-bar water retention in yellow-brown loams M.P. Tuohy ...... 55 7 SOIL CHEMISTRY ...... 57 Survey chemistry of yellow-brown loams L. C. Blakemore, B.K. Daly ...... 57 Cation exchange properties of yellow-brown loams D. C. Edmeades ...... 61 Sorption of phosphate by selected yellow-brown loams R. W. Tillman, J.K. Syers ...... 63 Magnesium status of yellow-brown loams M.A. Turner, R. Lee ...... 65 Sulphate retention studies of three yellow-brown loams P.L. Searle ...... 68 8 BIOLOGY ...... 77 Faunas of yellow-brown loams G. W. Yeates, H.P. McColl ...... 77 Microbial biomass of some yellow-brown loams under pasture and maize cultivation D.J. Ross, K.R. Tate .. 78 9 AGRICULTURE ...... 81 Agriculture on Waikato yellow-brown loams B.A.J. Smith ...... 81 Agriculture on Taranaki yellow-brown loams B.J. Hockings ...... 83 Farming on the yellow-brown loams-Manawatu area P.R. Hockey ...... 84 Lime use and animal production in the King Country M.R.J. Toxopeus ...... 85 Review of lime research on Taranaki yellow-brown loams N.A. Thomson ...... 89 Potash requirements of the Stratford sandy loam as affected by rainfall N.A. Thomson ...... 92 10 HORTICULTURE ...... 95 Horticulture on the Waikato yellow-brown loams E.E. Toleman ...... 95 11 LANDI USE ...... 96 Land use capability of yellow-brown loams J.R. Fletcher, M.R. Jessen ...... 96 Yellow-brown loams and forestry G.M. Will ...... 102 Land use on the yellow-brown loams in the Tauranga-Te Puke district W.E. Cotching ...... 102 Recontouring of yellow-brown loams in the Te Puke district W.E. Cotching ...... 103 12 WATERQUALITY ...... 104 Spray irrigation of dairy factory wastewater on a Kopua silt loam K. W. McAuliffe ...... 104 Iron ochre in drainage systems affecting potential productivity of yellow-brown loams W.J. Climo ...... 107 13 BIBLIOGRAPHY ...... 109 7
1. DEFINITION AND CLASSIFICATION
YELLOW-BROWN LOAMS-DEFINITION AND CLASSIFICATION
J.D. Cowie, Soil Bureau, D.S.I.R., Lower Hutt
The yellow-brown loams of New Zealand were from fine-textured volcanic ash of andesitic and first classed as brown podzolised soils in the soil rhyolitic composition; from alluvium from ash; and survey of part Waipa County (Grange et al. 1939) from sediments containing ash. but their distinctive character was noted and it was suggested that they would be better as a group on Subsoils are yellow-brown to brown, are very their own, and that they had strong affinities to the friable, and in handling break down readily almost brown loams from basalt. They were described as to a powder. When wet, the soils feel somewhat forming from young deposits of volcanic ash and slippery rather than sticky. The dominant clay having a powdery consistence with a fine granular mineral is allophane which is not present in other structure. The silica/alumina ratio was less than 2 yellow-brown soils from sediments. and they had high phosphate fixation. In the North Island General Survey legends the The distinctive properties of these soils and the soils were grouped into suites based on the problems that were encountered in farming them differences in the nature, composition and method encouraged early soil workers to investigate their of deposition of the parent ash and included suites properties. As far back as 1933, Taylor pointed out such as Takapau and Levin where the soils are the low silica/alumina ratios of these soils and derived from loess or alluvium containing tephric suggested that the clays which were present were material. similar in composition to the clay mineral allophane Within each suite, the soils were arranged in (Taylor 1933). He also reported on experiments sequences of soil development with four stages which showed their high phosphate fixation and generally being recognised-immature, semi suggested that the high amounts of aluminium and mature, submature and later semi-mature. These iron hydroxides in these soils could combine with represented increasing stages of leaching and soil added phosphate to form insoluble compounds. He development, dependent largely on rainfall and indicated the practical effect of that in regard to vegetation. phosphate topdressing and made a plea that investigations into the reaction of the soil clay with Definitions for the individual stages were not very phosphate fertilisers were urgently required-this detailed and are given by Pullar (1979) as follows: plea has not gone unanswered. 1. Young, immature: black topsoil; base saturation In the light of knowledge at the time, Taylor 30-50%; 1100-1500 mm rainfall; vegetation of (1933) also thought that the main soil-forming scrub and fern-Opotiki, Egmont black. process in these yellow-brown loams was laterisation 2. Immature to semi-mature: base saturation 25%; (leaching of silica with relative increase of iron and 1500-1800 mm rainfall; forest vegetation aluminium) rather than podzolisation (leaching of Ohakune, Stratford. iron). However, podzolisation could be superim posed on previous laterisation in areas of higher 3. Mature (later semi-mature?): base saturation 7- rainfall and mor-forming trees with acid humus. 15%; in places grey layer; 2000-2500 mm rainfall-Mairoa, Patua. Grange (1945) in his description of the soils of North Island classed the yellow-brown loams as a On the 1948 Soil Map of New Zealand (Taylor subgroup of the brown loams which were defined as 1948) the yellow-brown loams were regarded as a soils from andesite, basalt and dolerite rocks and separate intrazonal group. They were subdivided volcanic ash. The yellow-brown loams were formed into three subgroups: weakly and moderately from fine deposits of andesitic and rhyolitic ashes. leached; strongly leached; and weakly and moder They were defined as friable, brownish soils with a ately leached, shallow on gravels. granular 'fluffy' structure. The soils from what is In the South Island (N.Z. Soil Bureau 1968a), now regarded as tephric loess and alluvium in friable yellowish brown soils in the Te Anau Basin southern Hawke's Bay, Wairarapa, Manawatu and and the Waiau Valley were classed in the yellow Horowhenua districts were included with the yellow brown loam group. They are formed from moraines brown loams. and outwash gravels containing diorite, gneiss, This grouping was followed in the General Survey sandstone and minor amounts of basic volcanic of the Soils of North Island (N.Z. Soil Bureau 1954) rocks. They have many of the properties of the where the yellow-brown loams are defined as soils North Island yellow-brown loams such as high 9 8
yellow-brown loams from yellow-brown pumice It could be argued that the criteria put forward climate and fineness of the tephra may be critical. soils. depend too much on laboratory measurements, and phosphate retention, low bulk density, and high For instance in Tongatapu, Tonga soils on tephra many people would like to see more field criteria. content of amorphous iron and aluminium oxides, which is much younger than 20 OOO years are 7. The relationship of Tamm aluminium to However, I doubt if soil classification can ever be but these properties may be primarily due to the brown granular loams rather than yellow-brown phosphate retention. Mr L.C. Blakemore (pers. purely a field operation or whether these would be podzolisation process in many of the soils. comm.) has shown that when Tamm Al is plotted loams. of much advantage if it were. against P retention the yellow-brown loams fall In the technical terms of the New Zealand genetic 2. Colour-colours of B horizons are yellowish classification (N.Z. Soil Bureau 1968b), the yellow within a discrete range. For most of the criteria, data are already available brown or brown. brown loams are first classed as fulviform soils at for a range of critical soils. Experienced pedologists None of these criteria, however, except the parent 3. Structure-structure in A horizons is moderately can judge many of the criteria from field Category I to include all soils with yellow.is~ bro~n material one, will separate the yellow-brown loams to brown subsoils which occur characteristically in to strongly developed nut in contrast to the morphology and can extrapolate data to soils where from soils such as the high country yellow-brown weakly developed crumb or granular structure in none are available. humid areas and which are typically well drained. At earths and some podzolised yellow-brown earths, Category II, whkh indicates the main energy status yellow-brown pumice soils. B horizons have a and further work is necessary on this. Mr L.C. The stimulus of Soil Taxonomy (Soil Survey Staff weakly developed nut structure breaking to fine of the soil, most are in the temperate zone and so are Blakemore (pers. comm.) has suggested using the 1975) has brought a resurgence of interest in the crumb or granular. Brown granular loams have a classed as (pro-) fulvous. ratio of Fe and Al extracted by pyrophosphate at yellow-brown loams and it is heartening to see the much more strongly developed nut or block It is at Category III that the yellow-brown loams pH 10 to that extracted by citrate-dithionite, but this development of current studies by laboratory are separated from the main body of the fulvous soils structure. may not separate out the strongly leached yellow workers and the co-operation that is developing on the basis of the dominant kind and grade of 4. Consistence-yellow-brown loams have very brown loams from podzolised yellow-brown earths. between them and the pedologists in these studies. friable subsoils with dry bulk densities below Through these we should gain more information argillisation and classed as alvic soils. These have Flach (1972) has suggested, among other criteria, 0.85 Mg!m3. These criteria can be used to define which will help in the characterisation and amorphous day minerals in contrast to the fulvic that exchangeable aluminium (as extracted by KCl) boundaries with intergrades to yellow-brown classification of these soils, and of course ultimately soils which have layer silicates. They are also could be used to
gravel size. Some yellow-brown loams do show loams more closely together. The majority of soils in At the subgroup level most yellow-brown loams compared to extractable bases, expressed relative to placic horizon development, e.g. on the Mairoa the group and its intergrades satisfy the criteria for fall within Typic sub-groups. If there are distinct or the amount of clay present (as measured by the 15- prominent medium or coarse mottles due to plateau, but generally this horizon occupies less than inclusion in the Andisol order (after the few ba~ water r~tention of previously dried samples). 50% of the pedon and is not used for separation at representatives of Spodosols, Ultisols and Alfisols segregation of iron, or if mottles have chromas of 2 Sods belongmg to the Hangatahua series show this great group level. (Placudands may conceivably exist are separated). The abbreviated criteria which are or less within 1 m of the soil surface or if the soil is and are classed into an Allie subgroup. in some of Central North Island hill country but they essential for the inclusion of yellow-brown loams in artificially drained (and the soil does not belong to have not been reported to date). Thus the yellow the Andisols are that they have: the A~uand suborder), then an Aquic subgroup is brown loams are classified at this level either on the 1. either a mollic or umbric epipedon or a cambic recogmsed. Some of the Haplaquands (and possibly Acknowledgment basis of the 15-bar water retention of the fine-earth horizon or the upper 18 cm after mixing has a Hapludands) may belong to Vitric subgroups. fraction (if less than 20% classed as Vitrandepts), or colour value of 3 or less and contains >3% or Another property recognised in the recent to yellow We thank W.E. Cotching and B.R. Purdie for according to the' base saturation of the subsoil more organic carbon in the fine earth fraction brown loam composites and intergrades is a information on yellow-brown loams in the South (Eutrandepts versus Dystrandepts), a criterion no and 2. to a 35 cm depth from the surface or between relatively high level of KCl-extractable alu~inium Auckland and Bay of Plenty districts. longer applicable to the classification of soils with 25 cm and 1 m depth, either a bulk density of variable charge. Only a few yellow-brown loams key the fine earth fraction that is less than 0.85 3 out as Eutrandepts, and most of the central yellow Mg/m (now revised upwards to 0.9 Mg/m3) brown loams are Dystrandepts. A few soil series, and the exchange complex is dominated by e.g. Ohaupo series, have base saturation values that amorphous materials (new proposals by Mr lie very dose to the boundary between these two L. C. Blakemore for measuring this property CLASSIFICATION-FAO/UNESCO great groups. Those yellow-brown loams derived are outlined briefly on p.8 of this volume) or from the coarser volcanic materials (which range 60% or more by weight of non-calcareous vitric R.B. Miller*, Soil Bu·~.....0 u, D . SIR... , L ower H u tt from pumiceous lapilli to lithic stones) belong to the volcaniclastic materials and the pH (in the Vitrandepts. major part of the specified depths outlined The yellow-brown loam intergrades which are above) of 1 g of fine earth in 50 ml of 1 M N aF To classify the New Zealand yellow-brown loams The Vitric subgroup soils are essentially the classed as Ochrepts are separated at the great group is 9.2 or more after 2 minutes. in the FAO/Unesco system the legend to soil units in yellow-brown pumice soils. The yellow-brown loams level into: ~olume 1 of the Soil Map of the World (FAO 1974) is used. are divided among the other three. The Mollie and (i) those with a ustic moisture required (Ustoc The former suborder of Andepts and the great group of Andaquepts are thus transferred to this Humic Andosols are Andosols with thick dark A hrepts) e.g. Takapau series .T~e ~ndosol unit is reached in the key after the and (ii) those that do not have high base status new soil order. This means that the bulk of the horiz?ns of high . and low base status respectively ehmmatmn of Histosols, Lithosols, Vertisols, (molhc an_d umbnc epipedons in 'Soil Taxonomy'). (Dystrochrepts), examples including some of yellow-brown loams and many of the intergrades Fluvisols, Solonchaks and Gleysols. Andosols are ~he Ochnc Andosols have an ochric epipedon and the soils currently mapped in the Dannevirke and composites with recent soils are included in the soils: fme textures and/or smeary consistence. set (see Purdie in this issue). new order, together with yellow-brown pumice soils. having either a mollic or an umbric A horizon At the subgroup level occasional series have Most soils with properties that would satisfy the possibly overlying a cambic B horizon In separating out New Zealand soils at a scale of 1:5 OOO OOO in the Soil Map of the World (FAO epipedons thick enough to be considered Typic requirements for Aquands at suborder level would or an ochric A horizon and a cambic B horizon 1978) the amount of the critical chemical data Dystrandepts (e.g. some Patokaprofiles). However, not be included within the yellow-brown loams but having no other diagnostic horizons (unless buried needed for ~eparating the subgroups was quite small. most central yellow-brown loams are classed as would be classed in the genetic group of gleys. by 50 cm or more new material) Morphological data were also hard to find. The Entic Dystrandepts because the epipedon is However Taylor (1964) did include some 'diffusely having to a depth of 35 cm or more one or both of: decisions were 'informed estimates'. The results, for generally too thin to satisfy inclusion in the Typic gleyed volcanic soils with a flushed iron pan' in the (a) a bul~ density (at 1/3-bar water retention) of what they are worth ten years later, placed subgroup. This separation has been of some concern yellow-brown loam genetic group. These soils would the fme earth (less than 2 mm) fraction of 3 407 OOO ha of Taranaki soils in the Humic Andosols to overseas visitors as it is recognised that the comprise both yellow-brown loams with basal the soil of less than 0.85 Mg/m and the 513 OOO ha of Waikato soils in the Ochric yellow-brown loams are typical of global Dystran subsoil gleying (and thus belong to Aquic sub exchange complex dominated by amorph Andosol~ (with Vitric Andosols and Humic Andosols in depts. In the new Andisol proposals these soils key groups), and soils that should more properly be ous material; out in the Typic rather than Entic subgroup. regarded as gleys (and hence belong to the Aquand (b) 60% or more vitric volcanic ash, cinders or association), and an area of 75 OOO ha near suborder). Yellow-brown loams and composites other vitric pyroclastic material in the ~ilt Auckland of Ochric Andosols (with inclusions of Entic subgroups are not recognised within the with recent soils at higher elevations occur within a sand, and gravel fractions. ' Humic Acrisols). Ochric Andosols were also Vitrandepts, so that the stony yellow-brown loams associated with or included in Dystric Cambisol units frigid temperature regime and are classed as The sub-units are: and those intergrades with yellow-brown pumice Borands. The bulk of the remaining yellow-brown in the inland Taranaki hill country and the hill soils fall largely within the Typic subgroup. Some Mollie Andosols: Andosols having a mollic A country of the west coast from Taranaki to loams have a udic moisture regime and are included horizon. Vitrandepts adjacent to topographic depressions in the Udand suborder. Auckland. show subsoil gleying beneath a cambic horizon and Humic Andosois: Other Andosols having an work in Taranaki would today allow more are classed in the Aquic subgroup (e.g. Oaonui and At the great group level the majority of yellow umbric A horizon. R~cent detail to shown there with possibly more Ochric Tipoka series). brown loams, and their intergrades and composites, Ochric An~osols: Other Andosols having a smeary b~ are classed as Hapludands. Those with a low 15-bar c~ms1stence and/or having a texture which is And?sols mcluded. Other papers will no doubt The Otorohanga series, classed as a Eutrandept at water retention (less than 15 % on weighted average silt loam or finer on the weighted average provide the necessary information to clarify this. To the great group level, belongs to the Entic subgroup. of all previously dried samples from all horizons for all horizons within 100 cm of the surface allo~ cross r~ferencing, the following approximate between 25 cm and 1 m and less than 30% on Vitric Andosols: Other Andosols. . eqmvalences m New Zealand may be helpful: undried samples of the same horizons) are separated CLASSIFICATION ACCORDING TO CRITERIA as Vitrudands (e.g. Horotiu, Newall, Hangatahua, FAO/Unesco Soil Taxonomy N.Z. genetic FOR THE PROPOSED SOIL ORDER OF Uia and some Burrell profiles). The soils mentioned Mollie Andosols Typic Eutrandepts Weakly leached YBL Typic Hapludands AND ISOLS are almost exclusively recent to yellow-brown loam Humic Andosols Typic Dystrandepts composites and intergrades. Those yellow-brown Oehrle Andosols Moderately and strongly leached YBL Entic Dystrandepts Moderately and strongly leached YBL In the proposal for classifying the soil order of loams classed as Aquands or Borands are separated Allie, Typic (Hydric?) Hapludands Vitric Andosols Andisols (prepared by Dr G.D. Smith, and dated 10 by identical criteria into Vitraquands (Norfolk Typic Vitrandepts Yellow-brown pumice soils ~pril 1978, see Leamy et al. 1980) new and series) and Haplaquands (Skeet and Patiki series), -___ Entic, Psammic Vitrudands, Typic Hapludands improved criteria for classifying volcanic ash soils Vitriborands (some Burrell profiles) and *Now at· D · S · I . R ., H ead Office, . Wellmgton. . are advocated which tend to group the yellow-brown Haploborands. 12 13
tephra from Egmont and Tongariro centres and allows the tephra to be recognised and identified of rhyolitic tephras from Taupo, Maroa and separately in composite deposits, and small Okataina Centres. Thin deposits of Taupo, quantities have been detected in the Mairoa Ash Rotoma, Opepe?, Waiohau, Rotorua, Rere and in Tirau Ash up to 100 km from Mayor whakaaitu, Oruanui, Tahuna? and Rotoehu Island. This is a further demonstration of the Tephras are likely to constitute most of the composite nature of soil-forming deposits of PARENT rhyolitic materials and the proportions of the volcanic ash in the North Island and of the value older deposits will tend to increase westward with for geographic names for these materials. distance from the source. No area of soil is known to be formed entirely -Tirau Ash is derived principally from deposits of H.S. D.J. Lowe and A.G. from Tuhua Tephra, but where it was the major rhyolitic tehpra from the Okataina Centre • .,.,,.,... t...... ,..,t of Earth Sciences, University of Hamilton component of the parent material Whangamata Ash (Rotoma, Waiohau, Rotorua, Rerewhakaaitu, has been used (N.Z. Soil Bureau 1954). This usage Okareka Tephras) with small additions of can continue with the added information that small andesitic materials (origin uncertain) and of quantities of Tuhua Tephra may contribute to the The yellow-brown loams of the Waikato composition as seen in the B and C horizons of the Kaharoa Ash and Taupo Pumice. Coromandel region are derived from weathered soil profiles (e.g. Ward 1967; Gibbs 1968; N.Z. Soil parent materials of Waihi, Tirau and Mairoa Ashes. -Waihi Ash is derived principally from rhyolitic airfall volcanic materials. These materials may be Bureau 1968; Bruce 1978). Where the deposits were The yellow-brown loams in terraces and fans are tephra from the Okataina Centre, but of differing either direct airfall deposits, or erosion products of limited to a contribution to the A horizon, the soil formed chiefly from sandy and gravelly alluvial or proportions from Tirau Ash (Kaharoa, Mamaku, these deposits, described as reworked ash in some forming materials were usually named as the colluvial deposits. These deposits are derived from Rotoma, Rotoma, Waiohau?, Okareka?, Haup publications. In the erosion products small amounts underlying older tephra e.g. Hamilton Ash, or as erosion of Pleistocene ashfall and ignimbrite aru and Rotoehu Tephras) and small additions of of other rocks may be included in the parent non-igneous rocks such as greywacke (N.Z. Soil materials mixed with small amounts from older Taupo Pumice and Tuhua Tephra. materials, and these additions may modify to a slight Bureau 1954). Thus the thin deposits of less than underlying rocks, collectively classified as the degree the chemical and physical properties of the 10 cm of Taupo, Kaharoa, Tarawera and Ngauruhoe -Whangamata Ash was originally applied to the Hinuera Formation (Hume et al. 1975). The age of soil as a yellow-brown loam. In larger amounts these Tephras were omitted from the maps and descrip coarse textured material in soil profiles in the the upper surface is estimated as 10 OOO years, and additions result in the formation of intergrades to tions of the materials forming the soil group. eastern side of Coromandel Pt:ninsula. Recent thin deposits of more recent eruptions may be yellow-brown earths or gley soils. However they were included in interpretations of detailed studies by Hogg (1979) have shown that included in the soil-forming materials. the chemical and mineral analyses of horizons of soil The volcanic ash materials may be of either this material is in part composed of a widespread types. In summary, the yellow-brown loams of the deposit from Mayor Island about 6000 14C years andesitic or rhyolitic ash composition; commonly W aikato-Coromandel region are formed principally ago for which the name Tuhua Tephra Formation they are of mixed origin due to accumulation at Recent studies of soil profiles in the Waikato from deposits of tephra from eruptions outside the has been proposed for stratigraphic purposes. different times from differing sources. These sources Coromandel region (Pullar 1967; Pullar & Birrell district, and from different sources at various times. This tephra is characterised by a peralkaline extend in a semi-circle of centres from Mt Egmont 1973b; Hodder 1974; Hodder & Wilson 1976; Hogg This marginal situation is reflected in the composite through the Tongariro National Park volcanoes, 1979), stratigraphic classification of ash beds in assemblage of minerals including aegirine not nature of the soil-forming materials. Taupo and Rotorua to Mayor Island in the Bay of adjoining districts (Vucetich & Pullar 1969; Neall found in other tephras. The presence of aegirine Plenty. The proportional contributions to the 1972; Topping 1973; Pullar & Birrell 1973a; present soils differ with distance from the particular Howorth 1975; Lowe 1979) and examination of source and with the directional distribution of the cores from peat swamps and lake sediments (Tonkin materials. For example, the elongated patterns of 1967; Davoren 1978; Low et al. 1980) have supplied tephras from historic eruptions of Mts Ngauruhoe mineralogical, geochemical and age evidence of and Ruapehu demonstrate the effect of contem specific tephra at particular sites. These indicate SOIL STRATIGRAPHY OF KEREONE, OHAUPO AND MAIROA SOILS IN poraneous wind currents. Local topographic fea potential contributions to parent materials of yellow WAIKATO AND TE KUITI DISTRICTS tures and aspect alter thicknesses of the ash deposits. brown loam soils on adjacent sites, some of which were used in preparing isopach maps of showers Early field research separated two major soil (Pullar & Birrell 1973a). However, owing to the forming materials of yellow-brown loams in the likely variations in original deposition over the R.L. Parfitt, S.M. Robertson, Soil Bureau, D.S.I.R., Lower Hutt Waikato which were named Mairoa Ash and Tirau region, and to the effects of erosion, biological and Ash (Grange 1931; Grange & Taylor 1932). Whilst transfers and weathering since deposition, there is G.E. Orbell, Soil Bureau, D.S.I.R., Hamilton the two overlapped, studies indicated that the Tirau no surety of uniform constitution of parent materials Ash was primarily rhyolitic and was the parent for either the group or the type of soil. Moreover, material of soils for about 30 km north-west of the even at studied sites there are deposits of In this paper the stratigraphies of Kereone, oxalate solution to remove allophane, prior to sand boundary of soil-forming thicknesses of Taupo unidentified materials and no certainty that a Ohaupo and Mairoa soils are compared with the mineralogy determinations. Pumice. Mairoa Ash extended westward from the complete column of tephra has been constructed. In stratigraphy of the Tirau silt loam reference site Tirau Ash boundary to the west coast. These names the circumstances, use of Mairoa, Tirau, Waihi and (Pullar & Birrell 1973b), on the basis of field Fig. 2 shows the stratigraphy of the tephras and were used during the General Survey of Soils of Whangamata Ashes as terms for the composite examination and sand mineralogy. tephric loess beds at each site. The coarse textured North Island, and two more-Waihi Ash and parent materials of the yellow-brown loams is being layer which occurred directly above the clay rich Whangamata Ash-were added to describe soil Sections examined were (1) Kereone gritty silt continued in soil descriptions. This practice does not 'Hamilton ash' material contained cummingtonite in forming tephras in the north-eastern part of the loam on Station Road near Walton (NZMSl restrict the identification of component tephras for the sand fraction and the layer was therefore Waikato-Coromandel region i.e. beyond the Tirau N57/179524) (2) Ohaupo fine sandy loam on identified as the Rotoehu Ash (c. 42 OOO years stratigraphic purposes. It allows the unnamed tephra Ash boundary (Taylor 1953). For purposes of soil Ngahinapouri Road near Ohaupo (NZMSl B.P.). deposits to be included in the stratigraphic column description and classification the deposits were N65/783311) (3) Mairoa gritty silt loam on west side once they have been positively identified. named Ash although believed to be composed of of road at Mairoa (NZMSl N82/505775) (Fig. 1). All A second tephra, which is clearly visible in dry faces of sections, occurred at about 50 cm. In the materials from several eruptions. Using the plural On existing information (e.g. Lowe 1981) the the sections were of a similar depth and appeared to Mairoa and Ohaupo sections the tephra can be Ashes may have made this dearer. following conclusions may be drawn: have similar stratigraphy. distinguished from the adjacent layers by the The Ashes were commonly recognised and -Mairoa Ash is derived principally from deposits of The sand fraction was separated from all the beds slippery 'feel' and the presence of many coarse described primarily from their properties and as yet undifferentiated multiple beds of andesitic at all the sections and treated with Tamm acid pores. The sand fraction from this layer had a 15 14
Tirau Kereone Mairoa 0 tp+
Depth rr rr
25
rk
isopachs ' Lake CD. Rotoruat;/ 1600s 100
,,,. 100 cm- -- Pal?
Kawakawa I H H isopachs I I N65/783311 I N82/505775 .. I l I .._ I tp = Taupo Pumice 2000 years BP Taupo rr = Rotorua Ash 13 450 years BP Re? rk = Rerewhakaaitu Ash 14 700 years BP L = tephric loess 'l Ok= Okareka Ash c. 20 OOO years BP Tongariro Kk = Kawakawa Tephra c. 20 OOO years BP Re= Rotoehu Ash c. 42 OOO years BP • H =Hamilton Ash pal= paleosol Figure 1 Map of Waikato region showing the locations of the four sites (A), the rainfall isohyets in mm (solid lines) and isopachs for the
Rotoehu Tephra and Kawakawa Tephra (dotted lines). 0 0 ( () ('~-- 0 layer was largely tephric loess. At all sections this 200 ,, 0 0 distinct white appearance clearly different from the tephric loess layer was firmer than the underlying () <._l l sand fractions of the adjacent beds. The sand Kawakawa Tephra and Rotoehu Ash. The sand appeared to be similar to sand from the Kawakawa mineralogy showed that the layer was composed Tephra (c. 20 OOO years B.P.) at the Tirau section largely of rhyolitic tephric material; however at (Pullar & Birrell 1973b) and the position in the 0 Mairoa and Ohaupo the presence of the basaltic 0 stratigraphic columns is similar to the position of the 0 0 Q hornblende (lamprobolite), brown stained glass (' Kawakawa Tephra at the Tirau site. Therefore this 0 (> (' and/or augite indicated an andesitic influence, and it 0 tephra is probably the Kawakawa Tephra. is likely that thin layers of andesitic airfall ash At all the sites examined, the bed directly above deposited during the period of loess accumulation the Kawakawa Tephra contained many, though (up to c. 16 OOO years B.P.) have been mixed with poorly defined, irregular 'loess balls' up to 2 cm in the tephric loess. It is possible that Okareka Ash and diameter. These 'loess balls' are sometimes present Te Rere Ash (both rhyolitic) may also have been in tephric loess in the Rotorua region (Kennedy incorporated during this period. 270 1980) and at the Tirau site this layer, 63-95 cm in The bed between the Kawakawa Tephra and the depth, is known to be loess. Correlation of this Rotoehu Ash was firmer than these tephra layers Figure 2 Correlation sections Kereone to Mairoa with the reference Tirau section. Locations shown in Fig. 1. layer, at all sites, with the post-Okareka/Kawakawa and appeared to be similar to the upper tephric loess loess layer at the Tirau section suggested that the 16 17
layer. The bed contained rhyolitic tephric material at workers have noted the high allophane content of all three sites and at Kereone and Mairoa the bed the Mairoa soil and the associated properties of low also contained black manganese oxide particles. The bulk density and high water holding capacity, and material may be largely tephric loess but it lacks since these are the properties of andesitic ash soils, 'loess balls' and it may also be in part Mangaone or they have inferred that andesitic ash is present at Maketu Tephras. Mairoa (see review in Hodder & Wilson 1976). In contrast, the Tirau soil contains less allophane and Layers where the percent glass was low and where more halloysite (Parfitt et al. this volume) giving the glass was pitted and showed brown spots may be higher bulk density and lower water holding p4 (Druce 1966); Kaupokonui ~ephra 1200 yr B.P. paleosols (Fig. 2). capacity, and it has been suggested that the ash at The tephric material above the post Tirau is less 'andesitic' than the ash at Mairoa (see p3 (Druce 1966) Okareka/Kawakawa loess layer at all three sites was Hodder & Wilson 1976). 'fluffy' and the sand mineralogy indicated that it was The so called andesitic nature of these soils rhyolitic. No loess is associated with Rerewhakaaitu Correlated with observed previously can probably be equally well Manganui tephra 3200 yr B.P. Ash (c. 16 OOO years B.P.) or younger tephras (N.M. Stratford Ash ----=t explained by the weathering of rhyolitic glass to -lithic tuff Kennedy, personal communication). Therefore the allophane. This takes place more rapidly at Mairoa, (Druce 1966) fluffy material deposited on top of the firm tephric where more leaching occurs, than at Tirau, and loess layer probably includes the recent tephras 0 0 0 0 hence gives rise to a more allophanic ('andesitic') 0 0 p2 (Druce 1966); Inglewood Tephra 5000 yr B.P. (~16 OOO years B.P.) found by Lowe et al. (1980) in soil. Our results do not support the presence of large a Jake core near Hamilton. Although these tephras amounts of andesitic tephra, but small additions cannot be positively identified, because they are thin from Tongariro and Egmont Centres have probably 0 0 0 0 0 .. pl (Druce 1966); Korito Tephra and have probably been mixed and weathered within been incorporated in all the soils. the soil, the 18-33 cm layer at Mairoa contained a sand fraction very similar to the sand of the Many other sections with similar stratigraphy to 0 ~ 0 Rerewhakaaitu Ash layer at Tirau. The surface these three soils have been observed in the Waikato 4 horizons were gritty or contained soft brownish and Te Kuiti districts and we support the suggestion lapilli thought to be Taupo Pumice. (Pullar 1978) that the portmanteau names 'Tirau Stratford Ash ash' and 'Mairoa ash', describing layers of tephra These results indicate that the soils studied are (Aitken et. al. 1978) o ·o ~ ES and loess in these areas, should be abandoned. Vertical scale composed largely of rhyolitic tephric material which has accumulated either as wind blown dust or as airfall ash. The stratigraphy of the Mairoa, Ohaupo, Kereone and Tirau sections is essentially the same E4 but the ash deposits are thicker at Tirau because this Dr J.D.G. Milne for his assistance in the site is closer to the volcanic centres. Previous preparation of this manuscript. I I I r1 ELUCIDATION OF TARANAKI A A I I OOO o 0 E3 OOO o 0 L A.M. Geddes and V.E. Neall Department of Soil Science, Massey University, Palmerston North 0 0 0 KEY 0 0 Egrnont Ash .. .. 0 ,, A ' Lithic la pill i "'0 \,.. ', 0 The first soil survey of Taranaki was conducted at what constitutes the 'Stratford Ash' and must also be (Aitken et. al. 'o o ,q , o E2 o' ' •o" 1 inch to 4 miles scale by Grange and Taylor (1933). considered in any definitive work. The first of these 1978) ' ''£ o, ,, 0 EQJ Purniceous lapilli In it, three widespread tephra showers were was an indirect reference by Druce (1966) in a study :, 0 .. ' ',,. 0,10 recognised as soil-forming-(1) the Egmont, (2) the involving the tree-ring dating of recent Egmont ~ Mafic crystals 0 0 Stratford and (3) the Burrell Showers. These eruptives. As part of his study, Druce described four 0 0 showers were thought to be younger than the pumiceous and other interbedded tephras exposed Cemented ash mudflow deposits of the Opunake and Okato on the Stratford Plateau Road which he correlated 4 0 ("crearncakes") 0 0 districts, but this can now be shown as true only in with the 'Stratford Ash'. The second reference was 0 0 0 Mahoe tephra part. The Stratford Shower, the subject of our the soil survey of Stratford County (Aitken et al. • •• investigations, was thought to overlie the Egmont 1978). In this survey, Rowan and Lowgarth soil Shower and four principal soil series were series were separated from Stratford soil series 0 ... 0 0 considered to be derived from it. In an additional because they were considered to be derived from an o ... 0 Cardiff tephra report of their survey which is more extensive but unnamed, hard, andesite lapilli deposit younger than 0 classed as an internal unpublished document, the 'Stratford Ash', thus in effect defining an upper Grange and Taylor describe localities and sections of limit to this deposit (Fig. 1). the Stratford Shower which we now know to comprise a number of different aged pumiceous Our current investigations show the Rowan and tephras derived from Mt Egmont. Two later Lowgarth soils to be derived from three tephra publications refer specifically to interpretations of showers distributed (up to 250 mm thickness) 15 km Figure 1 Composite stratigraphic column of Late Quaternary tephras distributed east of Mt Egmont. 18 / 19 to the south-east of Mt Egmont. They comprise the (see Fig. 4). Isopachs of p2 (with possible thin Ii contributions of p3 and p4) show a broad Kaupokonui tephra and the p3 unit of Druce (1966), 0 5 !Oltm both pumiceous, overlying the Manganui tephra, a distribution to the south-east of Mt Egmont (Fig. 3), scoriaceous lapilli and lithic tuff, dated at c. 3200 the 240 mm isopach extending from near Kaponga years B.P. Fig. 2 shows the 300 mm isopach of in the south to Stratford in the east. The unit is l , tephra thickness from the base of the Manganui distinguished by its lOYR 8/2 (white) pumiceous , .. - \ tephra to the present soil surface (i.e. all post lapilli and blocks, and minor grey dense andesite Manganui tephras plus the Manganui tephra itself), lapilli which average 20 mm diameter, between .. together with the associated soil series. The isopach Stratford and Egmont National Park. ' extends as far north as the 100 mm isopach of the Beneath p2 is the unit informally designated pl ' \ Burrell Lapilli, beyond which the Burrell soil series \ (see Fig. 1). It is also directed to the south-east of Mt I is recognised. The original separation of Lowgarth I \ Egmont in remarkably similar distribution to that of (moderately leached) from Rowan soil series I I p2 (Fig. S) . It is distinguished by lOYR 8/3 (very pale ' (moderately to strongly leached) was made by & Mt. Egmont brown) pumiceous lapilli, 20 mm or less in diameter, . '"'.ea ' Aitken et al. (1978) along the 2000-2SOO mm rainfall between Stratford and Egmont National Park. zone, above which more iron mobilisation is evident. ·~.... Beneath pl is a minor unnamed lOYR 8/2 (white) The boundary between these two soils has been \ "'... pumiceous lapilli containing more lithic lapilli than '"" I STRATFORD extrapolated across the tephra showers shown in Fig. ·~\ -:-., pl and p2 (Fig. 1). 2. '~ /> 3Q0 MM ..... ~lr ' Of the tephras from which the Inglewood and Further below pl is unit ES (Fig. 1). The axis of .._ ...,B
N pumiceous and lithic lapilli, averaging greater than unit has a bilobed distribution to the south-east and 20 mm diameter. To the south the upper spalling east of Mt Egmont probably representing two 0 5 !Okm layer decreases in grain size to a lOYR S/6 (yellowish closely spaced eruptions. The lSO mm isopach brown) coarse ash. extends 16 km to the south-east and 19 km to the e~st (1'.'"ig . 8). The unit is distinguished by a , Beneath ES is unit E4, one of the key marker beds i KEY discontmuo~s layer of 7.5YR 4/2 (weak red) , .. - throughout the western parts of Stratford and cemented fme ash ('creamcakes') at its upper ' \ Eltham Counties (Fig. 1). Isopachs show a directed 0 ::••:::• : Bl = Burrell soil s boundary. I! is composed largely of loose, densely 0 : OG : axis of distribution to the south-east of Mt Egmont ' pac~ed pumiceous lapilli which vary from lOYR 8/1 Lo = Lowgarth soils (Fig. 7). (white) to 7.5YR 5/6 (strong brown) in colour. They I ' \ I are mostly between 10 and 20 mm diameter between I The 200 mm isopach passes to the east of Eltham ' : :::'-:_::-~,Re Rowan soils ~tratford and Egmont National Park and tend to be I -.'"' ,,,. ·' and Stratford. It is characterised by a central bed of mversely graded. Lithic lapilli are concentrated in I I spalling fine pumiceous and lithic lapilli inbetween . '"' .{:f~\ St = Stratford soils the upper part. Near source the pumiceous lapilli are .~ two. beds of coarse pumiceous and lithic lapilli strongly weathered, and become finer to form a I~ ,.- (which are greater than 20 mm diameter throughout loose ash in the east. •.-P the area west of Stratford). The upper bed is ,~!"" pred~minantly lithic towards the top, but also !h~ee columns illustrating correlation of the '"'0 \-;. co~tam~ 7.5YR S/6 (strong brown) pumiceous lapilli pnncipal marker tephra beds to the east of Mt ' oj>./ which mcrease in relative abundance with depth. Egmont are shown in.Fi?. 4 . The dramatic thinning The l~wer bed has an upper lithic-rich layer of the tephras even withm Egmont National Park is overly~ng a basal pumiceous lOYR 6/4 (light clearly visible, and beyond the Park boundary older yellowish brown) layer with minor lithic lapilli. tephras which are not preserved nearer to source Cemented ashes ('creamcakes') form discontinuous become soil-forming. layers m· two positions,· · firstly overlying the upper Acknowledgment Kaponga bed and secondly often in the central spalling bed where the ashes are internally stratified. Near the . This article ·is a preliminary report on part of the outer limit of positive identification to the south E4 field research into soils and ashbeds in Taranaki grades into a coarse ash with occasional lapilli. being fu.nd~d by. D.S.I.R. We gratefully acknow~ The lowermost unit considered by us to have been ledge this fmancial assistance. We also thank our contained within the original concept of the colleague, Dr J .A. Pollok, for his thoughtful Figure 2 Distribution of four soil series (Burrell, Lowgarth, Rowan and Stratford) as governed by the distribution of the Burrell Lapilli Stratford Shower is E3 (Fig. 1). Isopachs show this comments on a preliminary draft of this article. and post-Stratford Shower tephras (for stratigraphic detail see Fig. 1). KEY
0~~ Pumiceous c lasts
Grid Reference P20/053102 •.•.•Lithic clasts
Mt. e0~ Scoriaceous clasts Burrell Formatio '\ '.TITBuried soil Newall Formation I,·· - L '\ '\ .-iron pan Kaupokonui Tephr '\. R~-;'5'-spnr;i I ' '\. ' E:gmont pyroclastic ' '\ Park avalanche '\.. ' deposits '\.. ' ,, Q20/l 12089 Manganui '\. '\,, Vertical tephra ' ' 1o·.::'' ' - Q20/199088 -...... _ ' - -- ~ ..._...... _ ------' ...... _' ~ - - o-;;oQC'>oOo { -- oooo Oooo p2 p2 ------pl ----- ES "Stratford ---.-- .__. Ash" pl ------E4 •••••• ~-~~1~i~~ F3 diamicton -~- - ~ E2
Mahoe tephra 2. Egmont 1. Stratford Cardiff tephra Plateau Rd. National Park -near VHF 5 .6 km Boundary 9.0 km EAST -Stra tford WEST Hut . - entrance. 3. Monmouth Rd.
Figure 4 Correlation columns from Egmont National Park eastwards to near Stratford .
. - .- .- - .."l l~o~~; ... >z , - ~ -,;o;ii ~ ', ,.-z , , ,;i\\ ...... "' , ,::,o"\ ol .. ' ~o"\';i\' ...... ,. ' " , \.q, , I \,q, w ,' I ,,..., \ ';!. ' - .. N ' -\ r \f1 .. ~ Cl r c: ;o'en I I .. c , .., 3: , .. .. 3: , ~ iiQ" l>C> 3: c: ..... ·~ rt ... '"'aj" N .. .,,:s 3: 0 ., \3 0 '"" "' n ..... ::r i "'0 3 rt" ~· .,,., ., , n .,, , ::r ~:r ,, , .,,.,3 3 2, f.-' 5- a 0 3 0 2, g.<= a N...... trl VI <= a a. ;. "g. " a ...,~ ;. V> ~ !:! " ~ 0..., ...,~ g Q.. ., s"1 "1 VJ 0 g. 0 ::r I ~ ..., I ~ 0 El Q.. El 0 0 :!! VJ ::r ~ 0 :!! "~ ..,, ..,,
~ i 22 . 23
I I 3. DISTRIBUTION AND DESCRIPTION
0 !Oltm
, ]\~' , .. - EARLY SURVEYS OF THE YELLOW-BROWN LOAMS 1939-1954 , c ' ' ,-- ... I \ l W.A. Pullar*, Soil Bureau, D.S.I.R., Rotorua
' \ \ I 200 MM Yellow-brown loams do not occur in everybody's Thinking on the 4-mile soil map of the North I patch and they are not common like the gley soils in Island was crystallised at a conference in Wellington I I ' . '"' which a pedologist has a vested interest in bringing from 4-10 December 1940 when the framework of a ·~"" to light information on any aspect of gleying in a classification was drawn up (Pullar 1979). At that ·....~ local situation. Knowledge about yellow-brown time the yellow-brown loams were grouped with red •"1.•, ..... loams seems to have advanced in a series of brown loams and the brown granular clays and they \ -0 STRATFORD corporate statements by the New Zealand Soil were described as follows: ..... "The yellow-brown \ ?~"" Bureau, one in 1940 and the other in 1954, the latter loams are generally yellow-brown in colour, but may ... f:a,.lr ' being regarded as the bench mark statement for this include other related colours, e.g. dark brown. They • sub-group of soils for the period 1939-1954. Yellow are derived from volcanic ash deposits, either ' brown loams appear to have had a fascination for the andesitic or composites of andesitic and rhyolite, or '• first-generation pedologists and an air of sentiment from greywacke containing tuffaceous material. I• and perhaps even mystique. A learned pedologist Other characteristics are similar to those of the red EL THAM from the South Island was heard to remark that brown loams (derived from basalt)" .... (in that) 'they' in the North Island had very empirical rules ...... "In general, they have a good structure in the for identifying yellow-brown loams in the field, one top soil and arefree in the top portion of the subsoil, of which was to insert the forefinger into the subsoil with a low silica-sesquioxide ratio ..... " to see if the material would rebound to its original position- about as good a field test as any for A manuscript prepared for the D.S.I.R. Annual recognising this class of soil. Report 1940-41 summarising the work of I.J. Figure 7 Isopach map (in mm) of unit E4 of the Stratford Shower. Pohlen, H.S. Gibbs and J .D. Raeside in the East Footnotes on terms such as stages, sets and suites Coast and Central North Island regions (recorded by are added for the information of younger pedolog Pullar 1979) mentions yellow-brown loams as a ) ists. The first and second generation pedologists group of fluffy, friable and brown-coloured soils used these terms freely but as a third generation field 0 s lOkm found most extensively in the higher rainfall area INGLEWOOD man I scarcely understood them. I didn't have to-I along the eastern flank of the main axial came to fill in the classification framework already range .... "The soils may be formed from rhyolitic established. , (pumice) and andesitic ash from mudstones, , .. sandstones and conglomerates containing a propor -\ In the soils section of the 'Land Utilization Report , ' tion of volcanic ash .... "Immature, semi-mature and cl \ of the Heretaunga Plains' (Hughes et al. 1939) there submature stages were recognised1" .•.• A curious (" .... is no direct mention of yellow-brown loams but of a series of yellow-brown soils formed from alluvium young brown loam with which they are assumed to ' MM derived from mudstone, sandstones, conglomerates be analogous. The group has only one series, the and greywacke was found near the axial range at I Ngatarawa. I Takapau and Dannevirke ..... "The chemical and I I Soil descriptions in the bulletin, 'Soils and physical characters closely resemble those of yellow . '"' .. Mt . Agriculture of part Waipa County' (Grange et al . brown loams but it is thought that the climate is of •"' 3 ·~ 1939) are very pithy, and from the map legend it is some importance in determining the character of ..... these soils" .... "The only mature types mapped were •-t• assumed that the Brown Podzolised Soils represent \ "'« the yellow-brown loams. Two series were mapped, the light, fluffy soils at the foot of the Whakarara \ c; STRATFORD \ ?...... Horotiu and Ohaupo. The former is a sandy soil Range in Hawkes Bay .... " 100 MM occurring on flat terraces east and west of the "' f:a,.lr 250 MM In the bulletin, 'Soils and some related agricul """ .,.B~undary _ County, but nothing is said about the origin of the tural aspects of mid-Hawkes Bay' (Pohlen 1947) parent material, which is possibly derived from 100 --- yellow-brown loams are included in the Brown volcanic ash deposited by the Waikato and Waipa Rivers. The parent material of the latter is airfall rhyolitic and andesitic volcanic ash erupted from EL THAM 1Such differences in degree of profile development were denoted Rotorua-Taupo and Taranaki volcanoes. The by some early pedologists, notably the outstanding school of Ohaupo soil is a light brown powdery loam, easily California, as young, immature, mature and senile . A lthough cultivated, responding well to phosphate additions, these terms are now in disfavour since they have the connation of and is the principal soil of the rolling hills. a sequence of soil formation that must be passed through stage by stage, they are still useful adjectives for pedologists who can remember that in pedological usage the terms are applied in a comparative way and not necessarily in their ordinary Figure 8 lsopach map (in mm) of unit E3 of the Stratford Shower. • Current address: 33 Pegasus Drive, Sunnybrook, Rotorua connotations (Taylor & Pohlen 1962: p.68). 24 25
Loam group. They are formed from mixed In Bulletin 5 the yellow-brown loams are included YELLOW-BROWN LOAMS OF THE WAIKATO REGION greywacke alluvium and volcanic ash under a forest with the brown granular loams and clays and the red vegetation and a 900-2000 mm rainfall, and occur on brown loams as a sub-group of the brown loams. mainly flat terraces in the western part of the area Properties other than those mentioned above G.E. Orbell, Soil Bureau, D.S.I.R., Hamilton from Crownthorpe in the north to beyond the include a friable topsoil with a soft granular Makaretu River in the south. The soils have a dark structure. The subsoils are yellow-brown to brown, Yellow-brown loams are well represented in the brown topsoil and yellow-brown subsoil and a low are · very friable, and on handling break readily brown in the subsoil. The solum thickness is usually greater Waikato Region. They extend the pattern of silica/sesquioxide ratio due to high alumina. They almost to a powder. When wet the soils feel slippery less than 1 m (commonly about 80 cm) and rests on yellow-brown loams north and/or west of the were mapped in 10 units and classified into stages of rather than sticky and it was early recognised that marine terrace sediments generally with a paleosol. recent to young, young, immature and semi-mature. they contained a clay fraction high in alumina now Taranaki, King Country and Bay of Plenty Regions described elsewhere in this volume. It was noted that' in other districts with the same known to be allophane. It is not generally known vegetation and rainfall, podzols were produced from that yellow-brown loam soils are easier to map in the All of the region has been covered by Late FROM SUBAERIAL DEPOSITS weathered greywacke, whereas in mid-Hawkes' Bay Auckland district where the other soils are clays Quaternary, fine-grained rhyolitic and andesitic the addition of volcanic ash changes the soil from a than, say, in the Wellington district where the airfall volcanic ashes interlayered with loess beds, Elsewhere in this volume Gibbs et al. have podzol to a yellow-brown loam. neighbouring soils are silt loams. derived from various tephras, as described by Gibbs described the parent materials of yellow-brown et al. (in this volume). Some of these materials have loams in this region. The subaerial deposits forming Soil maps of New Zealand were published at a Yellow-brown loams have proved to be very parent materials for yellow-brown loams were scale of 1:2 027 520 in 1948, and in 'A descriptive useful to agriculture. They are easily worked and also been transported throughout the region by fluvial action, especially by the Waikato River and previously known as Waihi, Tirau and Mairoa ashes Atlas of New Zealand' (McLintock 1959) at a scale will grow good crops and first class pastures with a small area of Maihiihi ash also recognised of 1:3 200 OOO. Yellow-brown loams are distributed provided the soil is adequately fertilised with its tributaries, and redeposited with other sediments on terraces. (N.Z. Soil Bureau 1954). It is now recognised that in the south Auckland district, western Waikato and superphosphate and potash. Their main drawback is each of these 'ashes' is in fact a composite, layered, Raglan region, small areas of the coastal Bay of their ability to retain soluble phosphate, but this The airfall volcanic ash beds decrease in thickness deposit containing tephras from both the Taupo and Plenty and Gisborne districts, southern Hawkes' disadvantage is counterbalanced by good soil and grain size, northwards and westwards from their Okataina Volcanic Centres together with beds of a Bay, the Ohakune area, the Taranaki region, drainage and aeration. N .H. Taylor made the astute sources in the central part of the North Island, loessial nature but derived from tephras. Many of Manawatu and Wairarapa districts. The yellow observation ... . "In the northern part of the Island though in the southern part of the1 region where these layers may have been mixed by pedologic brown loams were included with the brown granular the yellow-brown loams, in effect, bring the light some additions of ash from the Egmont and and/or geomorphic action. Pullar and Birrell (1973b) clay loams from volcanic ash and described as friable texture, good aeration, and good drainage of the Tongariro centres are to be found, the distribution have described the composite column for the 'Tirau soils with clays high in alumina. A semi-formal text southern soils into the warmer climate of the north, pattern is more complicated. Ash'. Similar studies have confirmed the similar to accompany the 1948 map was not published until hence the rapid spring growth of the pastures, the On much of the hilly and steep land most of the nature of the 'Mairoa Ash' (Parfitt, Robertson and 1956 (Taylor & Cox 1956) but notes on the yellow quick response to summer rains, and the high Orbell, this volume). brown loams are the same as those given in the production per acre in the Waikato district. .. .. " Late Quaternary ash beds have been eroded. corporate statement of Soil Bureau, Bulletin 5 Consequently, although there are important It may be that soil surveys since 1954 will have For descriptive purposes the yellow-brown loams 'General Survey of the Soils of North Island, New differences in which part of the composite column is added little to the compendium of knowledge about of this region may be considered in two major Zealand' (N.Z. Soil Bureau 1954), and so are not incorporated in the solum of the various soils yellow-brown loams, in which case those first in the subdivisions: repeated here. recognised, they are essentially developed from field have won most of the gold leaving a few colours 1. From water laid sediments. similar materials, e.g. the Tirau soil is developed Mapping units, extended legend and classification for generations of pedologists to come. 2. From subaerial deposits. largely from the Okareka (with some added of yellow-brown ioams were formalised in Bulletin andesitic ash), Rerewhakaaitu, and Rotorua Ashes 2 5. The mapping units or soil sets numbered 137, with a little Taupo Pumice in the surface. The total grouped in stages into 11 suites3 , and were allotted FROM WATER LAID SEDIMENTS subaerial column extends below this to Rotoehu Ash reference numbers (extended legend and maps) at the bottom of the Late Quaternary column at from 48 to 79a. For example, the Horotiu suite (48) 2.69 m from the surface (Pullar & Birrell 1973b). At is formed from rhyolite alluvium with admixed In the Hauraki Graben and in the Waikato 2" .. . The soil set is a convenient mapping unit used on general lowland depressions, extensive, low angle fans of Mairoa (NZMSl N82/497741) the present author has andesite ash, the Tirau suite from Tirau ash4 (57), surveys in New Zealand and is a grouping of soils with like volcanic detritus (Hinuera Formation) were laid recognised the Late Quaternary column as being the Mairoa and Maihiihi suites from Mairoa ash4 , profiles or like assemblage of profiles. Its constituent soils need down by the Waikato River. These sediments are Maihiihi ash, Mairoa ash and Egmont ash, and not be geographically associated .... The sets are chosen to meet 0-18 cm Possible Rotorua Ash with some mainly sands and gravels of Hawera series age and Mairoa ash on sedimentary rocks (59 to 64), Egmont the practical objectives of the survey and not necessarily of equal Taupo Pumice pedologic rank ... . " (Taylor & Pohlen 1962: p.143). where well drained have given rise to the Waihou suite from Egmont ash (66 to 71), Waitemata suite 18- 33 cm Rerewhakaaitu Ash 3" . .• soil series in the Hauraki Graben and the Horotiu from water-sorted volcanic ash (72 to 73b), and The classification into suites is adopted . . . in the yellow 33- 53 cm 'Tephric Loess' ( + ?Okareka Ash) brown loams .. . because the nature of parent material imparts soil series in the Waikato. These soil series are 53-60 cm Kawakawa Tephra Takapau suite from pumiceous sandstone and special characters to all the soils derived from it thus causing the similar and are characterised by a 20 cm very dark conglomerate and from alluvium derived from 60-81 cm 'Tephric Loess' ( + ?Mangaone agriculturist to regard the whole suite as a broad unit from the brown to dark greyish brown, very friable A horizon Tephra Formation) greywacke and volcanic ash. Quite a mixed bag of farming point of view .. " (Taylor and Pohlen 1962: footnote p .26). with sandy loam (Horotiu series) or silt loam 81-98 cm Rotoehu Ash parent materials. 4These are now disputed as separate entities. (Waihou series) texture. This overlies up to 50 cm of 98 + cm Hamilton Ash strong brown sandy loam with very friable so in this case the whole of the column is consistence. Structures are strongly developed fine incorporated in the solum, not just the upper units. crumb throughout with a tendency to nut structure in the subsoil. This solum overlies only slightly As well as this compression of the Late weathered sands and gravels of the Hinuera Quaternary column as one moves away from the Formation. source of the tephras there is a major change in the climate between sites. The highest rainfalls for the Further north, extensive areas of rewashed region are experienced in the south-west (Mairoa Volcanic ash are found on low level marine terraces Plateau-2800 mm per year) while the drier regions adjacent to the Manukau and Waitemata Harbours. tend to be centred on the Hamilton and Hauraki These soils, the Karaka series mainly, are friable areas (as low as 1200 mm per year). These two With weakly developed nut structure and are variables, total thickness of the Late Quaternary commonly dark brown in the topsoil and strong column and rainfall, are considered the major 27 26
Depth Hori Stratigraphy Description controlling factors in soil development on these (cm) zon (provisional) subaerial deposits. 53-75 3Bwl 'Loess' 7 .5YR 4/4 (no colour change on crushing) clay loam; slightly Fig. 1 shows the form of the isopachs generally firm; moderately developed expected for ash showers from the Rotorua-Taupo medium and coarse blocky region and the general trend of rainfall over the structure crushing to moderately developed fine and coarse crumb region. structure; few roots (mostly Of these two variables it is probably rainfall which coarse fern roots); many coarse ~~ exerts the greatest influence on soil morphology. pores; some darker stains down '(i.\~~ old root channels; very few very At the drier end.of the sequence the yellow-brown fine pinhead Mn concretions increasing in number to base of \ loams tend to be slightly yellower in hue, while the horizon; diffuse boundary, wetter profiles tend to be slightly redder. This 75-f.7 3Bw2 'Loess' 7 .SYR 4/4 crushing to near ephra isopach form difference is not easily measured in terms of Munsell lOYR 5/6 gritty heavy silt loam; contours, thinning away notation, being only about one page difference slightly firm; moderately \ (lOYR to 7 .SYR hue) in the extreme case and is not developed coarse and fine from source (Rotorua everywhere consistent. Bulk density, however, is a blocky structure crushing to \upo region) weakly developed fine crumb feature which does change quite markedly, ranging structure; abundant fine and 3 from near 1.0 Mglm in the drier areas to about very firm black Mn concretions; \ 0.5 Mglm3 in the wettest areas. many coarse pores; very few \ x.~ discontinuous SY 4/4 cutans; \ "'(i.'c,V:. A series of soils on similar thicknesses of subaerial diffuse boundary, cover deposits, but with increasing rainfall is 87-101 4Bw Rotoehu Ash 7 .SYR to lOYR 4/4 fine sandy Kereone series ( <1200 mm rainfall per annum), loam; slightly firm; moderately • developed coarse crumb Ohaupo series (c. 1300 mm rainfall per annum), structure; many coarse pores; Te Kuiti series (c. 1600 mm rainfall per annum), few roots; many fine pinhead Mairoa series (c. 2600 mm rainfall per annum, white lapilli; diffuse boundary, These profiles and their ash stratigraphy are given 101-1084C RotoehuAsh 7 .5YR 4/4 sandy loam; slightly firm; structureless to weakly below. developed coarse crumb structure; many coarse pores; Kereone series. Grid Reference NZMSl N56/179524 very few roots; distinct Depth Hori Stratigraphy Description (cm) zon (provisional) boundary, Hamilton Ash 5YR 3/4 clay loam 0-24 A Taupo Pumice 5YR 2.5/1 gritty silt loam; very on SBt + Rotorua friable; moderately developed Ash+ fine granular structure breaking Rerewhaka to strongly developed fine crumb Ohaupo series. Grid Reference NZMSl N65/783311 aituAsh structure; abundant roots; diffuse boundary, 0-15 A Taupo Pumice lOYR 3/2 fine sandy loam; very + Rotorua few soft brownish (Taupo) 24-41 Bwl 'Loess' 5YR 3/4, 5YR 2.512 (50%/50%) silt loam; friable; weakly Ash+ lapilli; very friable; strongly developed medium nut structure Rerewhaka- developed granular and crumb crushing to weakly developed aituAsh structure; abundant roots; fine nut and granular structure; distinct boundary, many roots; (few very coarse 15-36 Bwl 'Loess' 7 .5YR 4/4 silt loam; very friable; fern roots); distinct wavy strongly developed fine crumb boundary, structure; few medium slightly firm 'clay balls'; many roots; 41-46 2Bwl Kawakawa 5YR 3/3 crushing to 7 .5YR 4/4 7 .5YR 3/2 silt infilled very Tephra very slightly gritty silt loam; friable root channels with very Formation slightly firm; weakly developed fine blocky structure (peds strongly developed very fine firm); 'clay balls'; crushes to crumb structure; diffuse strong coarse crumb structure; boundary, much of interstitial material 36-50 Bw2 'Loess' 7.5YR 3/4 silt loam; friable; between 'clay balls' has coarse many medium coarse, firm, 'clay Site Locations crumb structure; many roots; balls'; many roots; very few channel infillings of A abundant coarse and medium (D Kereone site horizon material; many thin pores; distinct boundary, @ Ohaupo site continuous 2.5YR 3/3 cutans; 50-60 2Bw Kawakawa 7 .SYR 4/4 slippery silt loam; @ Otorohanga site diffuse boundary, Tephra very slightly firm; weakly @ Te Kuiti site 46-53 2Bw2 Kawakawa 7.5YR 4/4 crushing to 7.SYR 5/6 Formation developed medium blocky @ Mairoa site Tephra heavy silt loam; slightly sticky; structure crushing easily to Formation friable; weakly developed fine moderately developed fine nut structure crushing to crumb structure; many coarse Figure 1 Tephra isopach form lines and rainfall (mm) isohyets with described profile locations. strongly developed fine crumb pores; few roots; distinct structure; many firm (up to boundary, 2 cm) 'clay balls' which are 60-74 3Bl 'Loess' 7 .5YR 4/4 heavy silt loam; firm; coarsely porous and crush to moderately developed medium strongly developed fine crumb and fine blocky structure structure; many roots; few very crushing to weak firm crumb thin discontinuous cutans; structure; very few roots; few abundant coarse pores; distinct pores; diffuse boundary, boundary, 29 28
Description Depth Hori Stratigraphy Description Depth Hori Stratigraphy (cm) zon (provisional) Few of the chemical parameters follow linear (cm) zon (provisional) Description between lOYR 4/4 and 5/4 silt on 6Bt Hamilton Ash 7 .5YR 4/6 crushing to 7 .5YR 5/8 trends, but overall tendencies are observable. There Depth Hori Stratigraphy 118-131 4Bw3 'Loess' (provisional) loam; friable; moderately clay loam; non-plastic; are trends which with increasing rainfall show- (cm) zon non-sticky; firm; weakly to 7 .5YR 414 heavy silt loam; firm; developed fine blocky structure; 74--90 3Bw2 'Loess' very few clay balls; few dark moderately developed medium weakly developed medium fine blocky structure; few near stained root channels; diffuse 1. Decrease in pH (especially in CaC1 , blocky structure; slightly more 2.5YR 2.5/4 stains on structural 2 boundary, massive and heavier in texture faces; very few roots confined to 2. Movement of organic matter down profile, than overlying horizon; distinct 131-146 4Bw4 'Loess' as above horizon but moderately cracks; very few coarse pores. boundary, developed medium blocky 3. Decrease in base saturation, mottled 7.5YR4/4 (70%) lOYR structure with more clay balls; Table 1 (pp.30-31) summarises the major 90-110 4Bw RotoehuAsh 4. Increase in Tamm Al, Fe, Si, 516 (30%) silt loam; very few diffuse boundary, chemical features of a sequence of profiles which, coarse grits; slightly firm; very 5. Decrease in Tamm Mn, 146-161 5Bwl Rotoehu Ash lOYR 4/4 heavy silt loam; firm; although from different localities, are stratigraphi weakly developed fine blocky moderately developed fine cally correlated with the profiles described above. 6. Increase in total and adsorbed S. structure crushing to medium blocky structure; few dark crumb structure; scarce roots; stained root channels; distinct many medium and coarse pores; boundary, distinct boundary, lOYR 4/6 greasy silt loam; 5YR 3/4 clay loam; plastic; 161-170 5Bw2 Rotoehu Ash on 5Bt Hamilton Ash friable; weakly developed sticky; very firm; moderately medium blocky structure developed medium blocky struc crushing to fine crumb structure; ture. distinct boundary, lOYR 4/4 clay; firm; many on 6Bt Hamilton Ash coarse pores; very few roots. Te Kuiti series. Grid reference NZMSl N74/679001 Mairoa series. Grid reference NZMSl N82/505775 7.5YR 3/2 silt loam, very friable; 0-16 A Taupo Pumice 7 .5YR 3/2 gritty silt loam; + Rotorua strongly developed fine nut 0-18 A Taupo Pumice + Rotorua slippery; very friable; strongly Ash structure crushing to strongly developed medium and fine Ash developed medium granular and crumb structure; abundant fine crumb structure; abundant roots, diffuse boundary, roots; distinct wavy boundary, YELLOW-BROWN LOAMS IN SOUTH AUCKLAND AREA 5YR 3/4 (crushes to 7.5YR 5/6) 16-28 Bwl Rotorua Ash 7.5YR 4/4 silt loam; very friable; 18-33 Bwl Rerewhaka- strongly to moderately aitu Ash slippery silt loam; friable; + Rerewhaka moderately developed medium B.R. Purdie, Soil Bureau, D.S.I.R., Havelock North aitu Ash developed fine nut structure crushing to strongly developed and fine blocky structure; many brittle peds; many roots; diffuse medium and fine crumb structure; many roots; diffuse wavy boundary, In the four mile mapping of the North Island Soils that are intergrades to yellow-brown loams boundary, 33-46 2Bw3 'Loess' 7 .5YR 4/6 (crushes to 7 .5YR (N.Z. Soil Bureau 1954) yellow-brown loams of the do not classify as Andisols. Tl36 is one such soil, 7 .5YR 4/4 silt loam with many 5/6) slippery silt loam; slightly 28-38 Bw2 'Loess' sticky; friable; weakly developed South Auckland area were mapped as major which is intergrading to a yellow-brown earth. It is distinct fine prominent 5YR components of the Karaka complex (72) and the an Orthoxic Palehumult, clayey kaolinitic, thermic. 2.5/2 stains down old root medium blocky structure; peds channels; very friable; weakly brittle; many coarse pores; many Torehape complex (73b), and as minor components T192 (Ohaeawai soil) is presently classified as a developed fine blocky structure roots; many distinct, up to 2 cm of the Waitemata complex (73) and Ararimu (85a) brown loam formed in weakly weathered basaltic crushing easily to strongly 'clay balls'; diffuse boundary, and Opita (86b) sets. ash and lapilli over vesicular basalt. But with developed fine crumb structure; 46-53 2Bw2 'Loess' as above horizon but less properties leading to its classification as an Andisol many medium and fine pores; developed structure; more 'clay Recent more detailed mapping has allowed the it might be better regarding as a yellow-brown loam. very few fine whitish flecks; balls'; fewer roots; distinct yellow-brown loams to be separated and identified. diffuse boundary, boundary, Because mapping and correlation are incomplete no In terms of the New Zealand genetic classification 38-56 Bw3 'Loess' as above horizon but slightly 53-60 3Bwl Kawakawa 10YR 4/6, 5/6, 6/4 mottled fine names are used for the soil series. The mapping has the soils form two major groupings. These are firm; diffuse boundary, Tephra sandy loam; slippery; firm to near massive; abundant coarse been based on Soil Taxonomy (Soil Survey Staff tentatively identified as sets: 56-72 2Bw1 ?Okareka Ash between 7 .5YR 4/4 and 5/4 silt Formation 1975) using amendments contained in the Andisol loam; extremely friable (falls pores; many fine 5YR 3/3 flecks; Firstly, the Torehape set is a composite yellow many thin 5YR 4/4 cracked Proposal (see Cowie this volume and Leamy et al. from cutting face); strongly brown loam on yellow-brown earth, defined here as coatings; few fine yellowish 1980) for details of ECDAM. Yellow-brown loams developed medium crumb a medial1 over clayey family. T140 is the most structure; abundant roots; aggregates; few roots; distinct and composite yellow-brown loams on yellow-brown boundary, commonly occurring profile. Tl83 is the same soil distinct boundary, earths classify as Andisols. Below is a listing of 7 .SYR 4/4 slightly slippery heavy but with no trace of mottles. T162 is a very wet soil 72-84 3Bwl Kawakawa near lOYR 4/6 greasy silt loam; 60-77 4Bwl 'Loess' families of Andisols that were identified. Numbers firm; moderately developed silt loam; firm; moderately in a toeslope position. Tephra developed medium and fine refer to profiles which have some of their chemical Formation medium blocky structure crushing to strongly developed blocky structure; few distinct and physical properties listed in Table 1 (p.32). Secondly, the Karaka set is a yellow-brown loam fine crumb structure; many fine 2.5YR 2.5/4 stains down old root and is defined here as a medial family. white flecks; many 5YR 2.5/2 channels; many coarse pores; Allie Haplaquand, medial over clayey kaolinitic, few roots; diffuse boundary, prominent stains down root acid, thermic T162 channels; few roots; diffuse 77-81 4Bw2 'Loess' as above but has many fine black Thapto-histic Haplaquand, medial, thermic 1Medial is a term used for a combination of particle-size and boundary, Mn concretions; diffuse Typic Hapludand, medial, mesic mineralogy classes for family classification in Taxonomy. The boundary, definition used here is that proposed by Guy D. Smith in 1978 84--103 4Bwl 'Loess' lOYR 4/6 heavy si.lt loam; firm Typic Hapludand, medial, therrnic which is: water retention at 15 bar is 12% or more on previously 'in situ' friable when dug; 81-94 5Bwl Rotoehu Ash 7 .SYR 4/4 fine sandy loam; Typic Hapludand, medial over clayey kaolinitic, moderately developed fine slippery; many fine 7 .5YR 5/2 dried samples; or water retention at 15 bar of undried samples is blocky structure crushing to patches; few distinct 2.5YR 2.5/4 thermic T183 between 30 and 100%; the exchange complex is dominated by strongly developed fine crumb 'iron plates'; many glistening Aquic Hapludand, medial, thermic T140 amorphous materials. Medial-skeletal and medial-pumiceous structure; few fine pores; very sand grains (?biotite); firm; near Aquic Hapludand, medial over clayey kaolinitic, classes are recognised where >35% of the material is coarser than few fine white flecks; diffuse massive but tendency to weakly thermic T135 2 mm. Field identification is based on loamy texture, reaction with sodium fluoride and association with andesitic ash. boundary, developed coarse blocky Lithic Hapludand, medial, thermic T192 structure; very few roots; few 103-118 4Bw2 'Loess' similar to above horizon but slightly paler in colour; diffuse coarse pores; base of horizon near continuous 1 cm thick iron boundary, pan; distinct wavy boundary, 31 30
Table 1 Chemical analyses of soil sequence. (Orbell)
Phosphorus (mg%) p Cation exchange Exch. Tamm extractable s Horizon pH 1:2.5 Organic matter Soil series Sample II.SM Inor-Organ-Total retn. CEC TEB BS Ca Mg K Na Al Mg,. Kc Al Fe Si Mn total ads. H 0 CaCl c N C/N Truog (Soil Bureau depth 2 2 (%) (me.%)(me.%) (%)(me.%) (me.%) (me.%) (me.%) (me.%) (me.%) (me.%) (%) (%) (%) (%) (ppm) (ppm) (%) (%) H 2S04 ;ganic ic lab. no.) (cm) 0.01M
7 185 202 140 342 91 34.9 19.1 55 16.7 1.14 1.09 1.8 1.85 0.11 4.3 0.71 1.9 0.64 0--19 Al 5.6 5.1 9.9 0.8 12 Kereone 31 38 63 101 97 21.8 15.1 69 14.2 0.54 0.15 0.20 5.2 0.91 2.6 0.32 19-28 A3 6.5 6.1 4.3 0.38 11 39 41 24 68 97 19.2 13.0 68 12.5 0.30 0.12 0.09 1.84 0.12 5.1 1.0 2.9 0.12 28--40 B2 6.6 6.3 3'.1 0.25 12 15 21 14 35 91 19.6 14.6 75 13.5 0.67 0.20 0.26 3.48 3.3 0.93 2.0 0.02 40--88 c 6.7 6.2 1.9 0.12 16 SB 8916 A-I 17 22 10 32 77 18.2 13.6 75 10.2 1.81 0.98 0.64 1.7 0.88 1.0 0.10 88--104 uA/B 6.8 6.3 0.8 0.06 13 14 18 10 28 70 16.6 12.2 74 7.4 2.60 1.52 0.67 1.6 0.82 1.1 0.04 104-123 uB 6.9 6.3 0.7 0.05 14 6 9 8 17 52 13.3 9.5 71 3.7 3.6 1.61 0.56 0.44 1.1 0.23 0.15 123--138 uC 6.7 6.0 0.5 0.03 17 7 11 10 21 68 16.5 11.2 68 4.1 4.8 1.80 0.51 0.51 1.3 0.19 0.26 138-148 IluAll 6.4 5.9 0.5 0.05 10 12 21 11 32 76 17.6 9.5 54 3.2 4.1 1.59 0.58 0.70 1.1 0.27 0.52 148+ IluA12 5.4 5.2 0.4 0.04 10
70 67 146 213 80 37.1 21.3 57 15.5 3.00 2.35 0.45 0.03 2.8 0.15 2.9 0.70 1.12 0.54 1420 53 0-4 All 5.0 4.8 11.6 1.02 11 2 Ohaupo 56 121 177 93 28.1 10.7 38 8.6 1.13 0.54 0.47 0.34 3.6 0.87 1.34 0.61 1080 53 4--15 A12 5.2 4.8 7.2 0.64 11 50 45 85 130 97 22.3 9.0 40 7.6 0.82 0.13 0.41 0.07 3.2 0.16 3.9 0.87 1.88 0.77 790 140 15-23 Bl 5.8 5.4 3.9 0.42 9 47 SB 9266 A-H 57 63 120 98 20.0 9.2 46 7.7 0.81 0.15 0.53 0.03 4.6 0.97 2.1 0.65 610 110 23-47 B21 6.3 5.7 2.7 0.33 8 48 21 26 22 48 97 19.4 10.2 53 7.4 1.84 0.16 0.81 0.06 2.9 0.81 1.54 0.16 240 4.8 47--62 B22 6.7 5.8 1.3 0.13 10 15 11 26 86 17.5 9.7 55 6.0 1.94 0.67 1.09 0.03 1.51 0.58 0.94 0.09 190 6.4 62-94 B23 7.0 5.8 0.5 0.07 7 11 9 12 6 18 92 15.5 9.0 58 5.5 1.59 1.03 0.91 0.00 1.23 0.62 0.73 0.12 160 9.8 94--106 B3 6.8 5.8 0.3 0.04 8 6 11 5 16 76 16.5 9.6 58 5.8 1.75 1.12 0.89 0.00 0.63 0.44 0.29 0.087 150 9.8 106--114 uB 6.8 5.7 0.3 0.04 8
47.6 38.7 81 33.0 3.1 2.43 0.12 1.18 10 3 155 165 177 342 90 4.9 0.02 4.9 0.96 1.9 0.44 VH* 123 Otorohanga 0-8 All 5.4 5.3 12.1 112 115 166 281 93 39.5 30.5 77 26.9 2.03 1.42 0.10 5.2 1.0 1.9 0.53 VH 70 8--14 A12 5.8 5.5 9.8 0.99 10 102 103 87 190 96 17.5 11.5 66 10.1 0.72 0.59 0.05 2.1 0.15 6.7 1.2 2.6 0.35 VH 451 14--32 B21 6.7 6.3 3.8 0.36 11 SB 9111A-G 102 107 47 154 98 17.4 10.9 63 9.7 0.81 0.27 0.11 6.7 1.3 3.2 0.22 VH 624 32-50 B22 6.8 6.4 2.4 0.24 10 37 44 21 65 98 16.4 7.8 48 5.3 2.02 0.36 0.13 6.3 1.4 3.0 0.030 VH 433 50--76 Cll 6.8 6.3 1.4 0.13 11 17 23 14 37 96 13.1 3.8 29 2.2 1.16 0.15 0.26 5.0 0.88 2.6 0.020 VH 87 76--99 C12 6.3 5.8 0.9 0.07 13 11 18 9 27 76 17.6 8.9 51 5.6 1.53 1.00 0.81 1.1 0.65 0.62 0.015 VH 13 99+ uB2 6.4 5.5 0.5 0.05 10
107 113 114 227 93 41.9 17.4 42 15.3 1.30 0.51 0.32 0.31 1.4 0.08 4.4 1.22 1.42 0.1)81 1230 48 0--12 A 5.3 4.9 14.2 0.99 14 2 Te Kuiti 28 37 55 92 99 26.5 5.6 21 4.7 0.51 0.21 0.15 0.03 1.4 0.09 6.1 1.43 2.2 0.065 1000 15 12-22 Bl 5.8 5.2 8.3 0.58 14 27 37 42 79 99 22.4 4.5 20 3.7 0.54 0.18 0.08 0.00 6.3 1.39 2.5 0.048 1420 730 22-34 B21 6.0 5.7 4.6 0.39 12 SB 9264 A-G 24 29 25 54 99 17.0 5.6 33 4.2 1.13 0.21 0.08 0.03 6.2 1.31 2.8 0.020 1990 1300 34--51 B22 6.4 6.0 2.7 0.21 13 20 25 17 42 99 13.7 5.2 38 2.9 2.06 0.18 0.08 0.00 6.0 1.39 2.8 0.006 1880 1390 51--67 B23 6.4 6.2 1.8 0.13 14 15 19 15 34 99 14.2 3.2 23 0.8 2.10 0.17 0.17 0.03 5.9 1.10 2.9 0.005 1720 1340 67-82 B24 6.1 6.0 1.5 0.12 13 13 16 16 32 99 12.2 1.2 0 0.3 0.63 0.16 0.15 0.03 5.8 1.00 2.8 0.012 1160 900 82-95 B3 5.9 5.8 1.2 0.09 13 85 35.4 8.9 25 7.0 0.86 0.71 0.31 0.43 2.2 0.09 4.6 2.4 1.13 0.020 1360 120 4.7 16.0 1.04 15 82 103 98 201 Mairoa 0--11 Al 5.1 44.2 2.2 5 1.8 0.15 0.10 0.13 0.53 0.59 18 22 28 44 72 91 1.3 0.12 7.0 2.9 2.0 0.005 1150 260 11-24 Bl 5.1 4.6 10.8 31.4 17 18 20 35 55 95 0.6 2 0.4 0.05 0.09 0.09 0.10 6.8 1.93 2.5 0.001 2090 1360 SB 9267 A-F 24-41 B21 5.2 5.1 5.5 0.33 12 15 32 47 92 22.0 1.5 7 1.1 0.10 0.10 0.23 0.00 6.7 1.54 2.4 0.003 2130 1580 41-57 B22 6.0 5.9 3.5 0.21 17 12 16 28 44 99 20.2 1.8 9 1.4 0.13 0.9 0.17 0.00 6.7 1.52 2.5 0.004 2160 1650 57--69 B23 6.1 6.0 2.9 0.16 18 16 20 33 53 99 23.1 1.5 6 1.1 0.13 0.11 0.18 0.03 6.9 1.87 2.5 0.003 2650 1950 69-84 uB 5.9 6.0 2.8 0.16 18
*Very high 33 32
YELLOW-BROWN LOAMS IN BAY OF PLENTY, POVERTY BAY-EAST COAST Table 1 Abbreviated data from profile descriptions and analyses (Purdie) AND KING COUNTRY DISTRICTS p :j: Profile Dry 15 bar water t pH retent- Vari. BS c no. Location Hori- Depth Colour Consis- Clay bulk W% NaF ion charge W.C. Rijkse, Soil Bureau, D.S.I.R., Rotorua (rainfall NZMSl zon tence density field :air dry (%) (%) (%) (%) mm) (cm) (%) (T/m3) moist
9.4 86 71 57 8.0 The distribution and description of yellow-brown POVERTY BAY -EAST COAST T135 N42 A 0-20 lOYR 3/2 friable 0.75 29.3 23.3 10.0 99 87 37 2.5 loams in Central North Island is best described by (1300) 4n 410 Bwl 20-42 7.5YR 517 friable 0.82 37.8 18.5 83 51 0.8 Bw2 42-51 7.SYR 518 firm 1.20 19.8 10.8 9.7 85 discussing each region separately. All regions have Few yellow-brown loams occur in these districts, 34 90 0.2 2Abg 51-65 lOYR 7/2 v. firm 17 1.59 8.5 7.1 8.0 9 in common the fact that the yellow-brown loams as weathered rhyolitic tephra overlying Tertiary rock 8.1 32 41 37 0.2 '2Btg 65-120 lOYR 7/8 firm 42 1.37 23.1 16.9 occur mixed with, or in a mosaic with, associated or thins out simultaneously with younger tephra such as related soils. This is largely a result of distribution of Taupo Pumice or Waimihia Formation. Most 8.4 66 65 61 4.4 T136 N42 A 0-17 10YR 3/3 friable 1.05 28.7 19.9 9.4 92 80 41 1.3 parent materials, such as patchy thin distribution of yellow-brown loam-like soils are therefore classified (1300) 422 413 Bw 17-46 lOYR 4/6 friable 0.99 34.1 18.9 62 34 0.3 2Btgl 46-70 SY 6/3 firm 41 1.63 19.8 16.3 8.2 29 Taupo Pumice or Kaharoa Ash ('parent materials of as composite soils (Mahia series, Tutira series, 46 26 0.3 2Btg2 70-98 lOYR 5/6 firm 70 1.17 32.5 28.4 8.1 35 yellow-brown pumice soils') and thinning of Kopuawhara series). 46 26 0.3 2Btr 98-120 SY 7/1 firm 85 37.2 32.2 8.0 38 weathered tephra overlying Tertiary rocks (sand In the northern parts of the East Coast, yellow stone, siltstone etc.). In other areas yellow-brown 28.5 9.8 94 73 51 8.3 brown loams have been identified mainly on flat to T140 N47 A 0-15 10YP. 3/2 friable 0.81 34.1 9.9 99 77 49 3.7 loams grade into podzols formed on the same parent (1300) 426 327 Bw 15-29 lOYR 4/4 friable 0.67 51.1 24.9 easy rolling terraces (Gibbs 1954; Rijkse 1980) 74 55 4.1 material, and form a complex pattern with them. 2Ab 29-42 lOYR 3/4 friable 0.64 52.7 24.8 9.9 99 where tephra has not been eroded off (Tikirau 74 58 2.2 2Bw 42-50 lOYR 4/4 friable 0.61 58.5 22.3 9.7 99 74 58 2.2 The pattern is even more complex on steep slopes series, Pakira series, Wharekahika series, Matekaoa 3Ab 50-60 10YR 3/4 friable 0.61 58.5 22.3 9.7 99 74 56 1.6 where a substantial part of the original tephra cover series). 3.Bw 60-75 lOYR 4/3 firm 0.65 60.6 21.6 9.6 99 40 1.7 4Bwl 75-99 lOYR 5/2 firm 69.3 24.4 9.4 99 76 has eroded off but remains on stable slopes and 12 3.1 4Bw2 99-125 lOYR 4/3 firm 103.1 31.8 8.9* 99 92 spurs. Such steepland soils can only be classified as being related to more than one soil group (e.g. 27.6 9.8 96 82 34 12.0 T162 N42 Aul 0-3 SYR friable 38.0 related to composite soils and yellow-brown loams). friable 38.0 27.6 9.8 96 82 34 12.0 (1300) 523 422 Au2 3-15 7.SYR 3/2 KING COUNTRY 2Ab 15-25 SYR 3/2 friable 39.6 25.2 9.9 88 19 19 It can be concluded therefore, that although 90 13 3Ab 25-48 lOYR 4/3 friable 66.7 30.6 10.1 98 87 21 yellow-brown loams occur frequently in the districts 3Br 48-60 lOYR 4/2 friable 57.7 39.v 10.1 97 Yellow-brown loams occur extensively in north 25 discussed below, they often occur in small 4Bwg 60-85 9YR 516 firm 26.6 14.3 10.1 87 88 ern, western and southern parts of the King 36.2 26.3 8.0 25 48 76 unmappable areas. 5Br 85-100 lOYR 5/2 firm Country. They have been subdivided according to 9.7 35 the kind of tephra they have been formed from, the N42 Au 0-18 7.5YR 3/2 friable 37 32.7 26.6 T183 20 kind of Tertiary rock underlying the tephra, and the 434 390 Bwl 18-36 7.SYR 4/4 v. friable 41 44.6 21.5 10.4 BAY OF PLENTY DISTRICTS (1250) 27 Bw2 36-46 7.5YR 5/4 friable 59.2 19.7 10.5 intensity of leaching (Rijkse 1976; Rijkse and Wilde 27 Bw3 46-57 7.5YR 7/4 friable 59.2 19.7 10.5 Yell ow-brown loams are most extensive furthest 1976; Wilde 1977). Thus the following combinations 16.7 12.6 8.5 60 BC 57-70 2.5Y 6/4 friable 33 away from sources of relatively recent tephra such as were separated: 2Cl 70-82 lOYR 6/6 friable 41 2C2 82-100 lOYR 6/6 firm 73 33.3 27.4 8.7 Kaharoa Ash, Taupo Pumice and Waimihia -weathered rhyolitic and andesitic tephra on Formation, and where older weathered tephras ignimbrite (Te Kuiti series, Ngakuru series 10.5 93 88 17 T192 N42 Au 0-19 lOYR 3/2 v. friable persist. The most extensive areas of yellow-brown 11.2 99 91 20 -weathered andesitic tephra on andesite (Tihia (1200) 403 495 Bw 19-40 7.5YR 4/4 friable loams occur therefore in the coastal areas, generally R 40+ vesicular basalt under a mild (thermic) climate. Katikati series series, Otamangakau series) occurs north of Tauranga along the coast, with -weathered andesitic tephra on ignimbrite *pH 10.5 after ultrasonic (1 minute) Waitekauri series at higher altitudes under higher (Ongarue series) tVariable charge. The amount of variable charge is calculated by substracting the bases + exchangeable Al from the CEC rainfall. These soils are formed by thin rhyolitic -weathered andesitic tephra on andesitic gravels obtained with BaCl2 at pH 8.2 (CEC8.2). tephra originating from Okataina Volcanic Centre (Kakahi series) CEC . - (bases +exchangeable Al) 8 2 x 100 overlying older tephra such as Hamilton Ash and Variable charge % -weathered rhyolitic and andesitic tephra on CEC8.2 Whangamata Ash. The rhyolitic tephra from greywacke (Pukerata series) Okataina Volcanic Centre become thicker towards -weathered rhyolitic and andesitic tephra on :j:Base saturation. Determined by ammonium acetate method at pH 7.0. Te Puke with thin Kaharoa Ash in the topsoil. These soils are identified as Te Puke series and they are weakly indurated sandstone (Mapiu series) well known as kiwifruit orchard soils. Further east -weathered rhyolitic and andesitic tephra on towards Opotiki, soils are formed from coarse indurated sandstone (Tumutumu series) Whakatane Ash and classification is difficult: where -weathered andesitic tephra on indurated sand coarse textures occur they are classed as yellow stone or silty fine sandstone (Waihuka series) brown pumice soils, and where fine textures occur -weathered andesitic tephra on banded mudstone they may have to be renamed and classed as yellow or sandstone (Tangitu series) brown loams. Further inland, yellow-brown loams occur locally (Waiteti series) or in association with -weathered andesitic tephra on mudstone (Matiere composite yellow-brown pumice soils on yellow series) brown loams or yellow-brown pumice soils (Ngak -weathered andesitic tephra on mixed alluvium uru series). (Aria series). 34 35
LOAMS TARANAKI
2 KEY Yellow-brown loams occupy over 3500 km of yellow-brown loam subsoils become progressively western Taranaki, and comprise one of the most gleyed as one moves towards the more poorly H~ HANGATAHUA + 0KATO valuable resources of the region. They have all drained sites. Tipoka series occupies intermediate developed from andesitic volcaniclastics erupted slope positions with imperfect drainage, showing a from Mt Egmont in Late Quaternary time. Bw horizon overlying mottled or reduced horizons. Ml\ERO Intermittent eruptions of volcanic ash onto the gently seaward sloping bush-covered landscape, Further south is the second lahar landscape unit u- UIA coupled with the humid climate, resulted in the where the Opua soil series is developed within a formation of these distinctive low bulk density, volcanic breccia forming the axial lithology of a 7000 w- WIREMU + SKEET + PATIKI friable, mostly free-draining soils. To the west of Mt year old lahar named the Opua Formation, with no Egmont, volcanic mudflow and debris flow ( collec tephra cover. The soil characteristically contains T- TAHURANGI tively termed lahar) deposits are extensive, resulting stones within a sandy loam matrix, is free-draining + Sl.JBALPINE + ALPINE SOILS in many stony yellow-brown loams. Along the and often very firm or hard in the subsoil. In stream channels radiating from Mt Egmont, fluvial imperfectly drained sites between lahar mounds the N- NEWALL gravel and sand deposits are parent materials of Oaonui series is recognised. Further to the south yellow-brown loam to recent intergrades as well as east and to the north-west of the Egmont series, the recent soils. In eastern Taranaki, yellow-brown third lahar landscape unit is recognised on the loams occur on ancient marine terrace remnants and marginal lithologies of the Opua Formation. Here on ridge crests which are capped by volcanic ash stones and gravel have been admixed and from both Mt Egmont and Mt Ruapehu, but in redeposited with volcanic ash as a distinct lithotype. STRATFORD adjacent steepland country these ashes have been Pihama series is recognised on free-draining sites removed by erosion so that the steepland soils are with the Skeet series recognised in imperfectly developed within quartzo-feldspathic lithologies and drained positions. assume properties more closely allied to yellow brown earths. The distribution of soil series is shown INTERMEDIATE ELEVATIONS on Fig. 1. At intermediate elevations two prominent trends LOW ELEVATIONS occur in soil properties. Firstly, the soil-forming tephras coarsen towards their source, an effect that Five landscape units with distinct soil associations is most extensive to the east of Mt Egmont. Here comprise the bulk of yellow-brown loams at low soils have sandy loam or gravelly topsails which elevations. The first is along the southern coastal contain numerous pale yellow pumiceous lapilli or plain, where under a mesic temperature regime the sometimes hard, dense, lithic lapilli. Grouped Egmont soil series is recognised as having formed collectively the lapilli beds were named the within distal andesitic tephra and tephric loess beds 'Stratford Shower' (Grange & Taylor 1933, Gibbs on free-draining sites. In low lying areas the soils 1968), extending from Inglewood in the north to become progressively gleyed, the Oeo series being Normanby in the south. Secondly, rainfall increases defined in imperfectly drained sites. The second with increasing altitude, resulting in moderate to landscape unit lies along the northern coastal plain strong leaching with attendant lower exchangeable where the New Plymouth series has formed under a bases and lower pH. Of the soils developed within thermic temperature regime from thicker, free the Stratford Shower, the Inglewood series is draining accumulations of andesitic tephras. Few separated from the Stratford series on the basis of imperfectly drained soils are recognised on this increased degree of leaching above 330-430 m landscape unit. elevation. Recent stratigraphic studies have iden tified three tephras younger than the Stratford To the west of Mt Egmont between the above two Shower (i.e. unnamed lapilli deposit of Aitken et al. landscape units is a complex lahar-covered land (1978): Kaupokonui tephra, p3 of Druce (1966), and 0 5 10 scape where the three other landscape units and Manganui tephra of Geddes and Neall, in this --...... --.--km corresponding soil associations are recognised at low volume). At intermediate elevation, soils on these elevations (Palmer et al. 1981 ). The first of these younger lapilli deposits are named Lowgarth series, shows the Warea soil series which occurs to the and at higher elevations Rowan series (discussed in south of the area where New Plymouth series is next section). Lowgarth series has coarse sandy loam recognised. It is developed from free-draining topsoils developed largely within the lithic lapilli VEN 1980 volcanic ash overlying lahar deposits at 0. 75 m depth rich Manganui tephra. or greater. The marked textural break in these soils often constitutes a paralithic contact, and it is an On laharic terrain to the west and south of Mt Figure 1 Distribution of soil series in Western Taranaki obvious site for lateral water movement and iron Egmont, the Kahui series is identified where deposition. In naturally enclosed depressions bet volcanic ash overlies laharic deposits at relatively ween lahar mounds in this landscape unit, the shallow depth (less than 2 m), up to 430 m 36 37
counties are wetter (mean annual rainfall 1300- grains, with lesser amounts of micas, chlorite and elevation. Te Kiri series is recognised on young very low exchangeable bases (TEB at 150-300 mm 1500 mm) and colder (mean annual temperature minor minerals such as epidote, zircon, tourmaline, laharic deposits with no tephra mantle where soils depth= 1.2 me.%), with iron mobilisation and about 2.5°C lower) than southern parts of the and garnet (Wilde 1974). Egmont series in the are stony, being developed directly within breccias accumulation along vertical cracks in road cuttings region, and fall within Climate District D2 of of the Opua Formation, up to 335 m elevation. being conspicuous (although these do not constitute Wanganui Region also contains layer lattice clays Tomlinson (1976). (chlorite, illite, and vem1iculite) formed from the Wiremu series is identified on the marginal placic horizons). The soil displays high water weathering of their non-andesitic mineral fraction lithologies of the Opua Formation at similar retention due to the large amount of poorly ordered Yellow-brown loams of the Wanganui Region altitudes and under similar leaching conditions. (In aluminosilicate clay and the wet environment; the have largely formed beneath a mixed podocarp (Wilde 1974). Mineralogical differences between Egmont series in Taranaki and in the Wanganui the region between Stratford and lnglewood .to. the 15-bar water retention of moist samples from 150- broadleaf forest comprising both mull- and mor east, poorly drained soils have developed w1thm a 300 mm depth is 78%. The distribution of the Patua forming trees. In the north of the region on elevated Region do not produce significant chemical thin ash cover over volcanic mudflow deposits and series is broken to the west by numerous younger sites under high rainfall, strongly mor-forming trees differences between these two soils, owing to the are currently grouped into the Norfolk series). debris flows from Mt Egmont summit which have including beech have produced iron- and humus masking effect of the amorphous constituents. overwhelmed older surfaces in pre-historic times. enriched B horizons. At all elevations, but more commonly at Within the valleys of the Whangaehu and (The Maero series, a recent soil, is distin~uished on Mangawhero Rivers in Wanganui County, small intermediate elevations, floods of boulders, stones, Near Wanganui, the indigenous forest was cleared these youthful gravelly and sandy deposits). scattered areas of yellow-brown loams named gravels and sands have swept along major stream during the past 60 to 100 years. In the Waimarino Kakatahi series occur. They have formed on high channels depositing alluvium as levees or as terraces To the north-west of Mt Egmont the Newall district, although clearing was started about the tum terraces, at elevations between 50 m and 275 m within close proximity to the stream courses. The eruptions which deposited up to 300 mm thickness of the century there were still large areas in bush at where deep deposits of fine gravelly resultant deposits are primarily volcaniclastic and of ash and fine lapilli about 450-500 years ago, have the time of the 1918 bush fires. It was not until heavy volcani~ alluvium derived from lahars occur. soils developed within them have been grouped into led to a separate soil series (Newall series) being machinery was available during the 1940s that large the Hangatahua series. A wide tolerance of soil recognised from 250 to 920 m elevation. scale clearing took place here. In the north-east of Kakatahi series was first identified by Campbell Rangitikei County, on the Kaimanawa Range, small profile variability has been included within this unit To the south-east of Mt Egmont the Rowan series (1977). It occurs under a mean annual rainfall in the past, with many textural variations identified areas of yellow-brown loams (Titapu series) have ranging between 1000 mm and 1250 mm and is is developed within similar parent materials to the developed under tussock. from sands to gravelly sands to silt loams. This has Lowgarth series occurring at intermediate eleva moderately leached. Profiles are freely draining with led to some confusion as to how these soils should be tions. In Rowan profiles, lapilli are coarser Egmont series in the Wanganui Region occurs deep, dark brown, friable A horizons having classified and they have been variously considered as compared with Lowgarth profiles, and show north-west of the Wanganui River, within Waitotara strongly developed subangular blocky structure; recent soils (N.Z. Soil Bureau 1954; Tonkin 1970), abundant iron coatings, especially between 400- and Patea Counties at elevations between 75 and over deep, very friable, sandy loam textured B yellow-brown loams (Aitken et al. 1978) and recent 760 m elevation. North of the Rowan series the 500 m. The series was first described by N.Z. Soil horizons with strongly developed crumb structure; to yellow-brown loam intergrades (Palmer et al. Burrell Lapilli (erupted in 1655 A.D.) thickens, and Bureau (1954) and more recently by Wilde (1974, over olive grey, firm, gravelly sand, on andesitic 1981). above 200 mm thickness the Burrell series (a recent 1976). It is formed from Holocene andesitic ash gravel. soil) is recognised from 460 to 760 m altitude. Where (Egmont Ash) mainly overlying Pleistocene Oha Ohakune series occurs throughout Wanganui, IDGH ELEVATIONS the Burrell Lapilli is thin towards its eastern margin, kean loess within 1 m of the surface, although in Rangitikei, and Waimarino Counties, as well as in it overlies volcanic mudflow and alluvium deposits. some places the ash overlies Pleistocene or early the southernmost parts of Taumarunui County. It At high elevations, largely within Egmont Soils within these parent materials are recognised as Holocene sands. It occurs on high coastal terraces. was first mapped and described by N.Z. Soil Bureau National Park, soils are developed within a humid or Uia series and are classed as a yellow-brown loam to Topography ranges from flat to gently undulating on (1954), and more latterly in the Wanganui and perhumid environment which results in strong recent soil intergrade. younger terrace surfaces, to rolling and strongly Rangitikei Counties by Campbell (1977, 1978). leaching and much iron mobilisation within predo rolling on older and more strongly dissected terrace Above 1100 m elevation, the Tahurangi series is surfaces. Ohakune series occurs in many small scattered minantly younger tephras. Only in the north, on the now recognised as having developed from 200 m~ areas at elevations between 300 and 600 m, east and flanks of the Pouakai Range and to the south-west of or more of andesitic volcanic ash of the Tahurang1 Egmont series occurs under a mean annual rainfall north of Atene in Wanganui County, mainly north Mt Egmont are older tephras soil-forming at this Formation, overlying older tephras, under a mean of c. 1000 to 1500 mm. Where the parent volcanic of Taihape within Rangitikei County, and as altitude. These deep ash deposits, with minor annual rainfall of 5700-7500 mm (Aitken et al. ash is thick, or where sandy materials underlie the extensive areas throughout the southern and western interbedded pumiceous lapilli layers, form the 1978). ash, the soil is moderately leached showing silt loam parts of Waimarino County. The series has formed parent materials of the Patua series. This series has or coarser textures throughout, together with friable from andesitic ash (Tongariro Ash) which occurs on and very friable consistence, and weak development stable slopes as deposits up to 1.5 m deep on a of structure. Where the parent ash shallows and the variety of landforms. Ohakune series occurs on flat older underlying loessial materials approach the to. undulating ridgetops, terraces, and toeslopes, on surface, Egmont series tends to be more weakly old high terrace remnants and on volcanic landforms leached, subsoil textures are finer, consistence is bordering the lower southern slopes of Mt Ruapehu. firmer, and structure is better developed. In a few places, on old terrace remnants and on the YELLOW-BROWN LOAMS OF THE WANGANUI REGION Characteristically the clay mineralogy of Egmont lower slopes of Mt Ruapehu where the ash overlies series is dominated by amorphous constituents, bouldery lahar debris, Ohakune bouldery loam is mapped (N.Z. Soil Bureau 1954). R.H. Wilde, Soil Bureau, D.S.I.R., Palmernton North resulting in a very high organic matter content of topsoils, very high% P retention, very high amounts Ohakune series occurs under a mean annual of non-occluded inorganic P, and high Tamm rainfall of c. 1100 mm to 2000 mm and is moderately Yellow-brown loams of the Wanganui Region are The climate of the Wanganui Region is described extractable Fe and Al. leached. Profiles have very dark brown, friable, by Tomlinson (1976). The Wanganui and represented by the Egmont, Kakatahi, Ohakune, Egmont series in the Wanganui Region is very loam textured A horizons, with granular and crumb Waimarino districts lie largely within his Climate Pokaka, Moawhango, and Titapu soil series. They similar morphologically and chemically to Egmont structure and some minor subangular blocky District D in which mean annual rainfall ranges occur within the Waitotara, Patea, Wanganui, series in Taranaki, having formed from andesitic structure; brown and dark yellowish brown, very between 900 mm and 1300 mm and rainfall is Waimarino, Rangitikei, and Taumarunui Counties parent materials of the same age and stratigraphic friable, loam and silt loam textured B horizons, with generally evenly distributed throughout the year, under a present climate characterised by warm position, under a similar climate. However, fine subangular blocky and crumb structure; over with annual water deficits of between 50 and summers and generally mild winters, except in the mineralogically the Wanganui Egmont series differs firm silt loam to clay loam textured C horizons with 100 mm in the south of the region. Mean annual northernmost parts of the Waimarino district where slightly from the Taranaki Egmont series as the weak blocky structure. In the southern part of the temperatures range between 12.5 and 15°C. winter temperatures are more severe than in the Th~ parent ash to the south is contaminated by abundant Wanganui Region, at greater distances from the northern parts of the W aimarino and Rangitiket south. sand- and silt-sized detrital quartz and feldspar parent ash source, textures of Ohakune series are 38 39
finer and consistences are firmer compared with 500 m and 1100 m in small areas of Waimarino rounded, largely unweathered, and contain only a brown gritty silt loam or sandy loam textures, with those in the Waimarino County where the volcanic County south-east of Ohakune, and in larger areas small proportion of fines. Near Manapouri, bedded weak nut or granular stn1cture, on brown to dark sands overlie the gravels to various depths. ash is coarser. within Rangitikei County, north-east, east and brown stony silt loam B horizons with weakly south-east of Waiouru. It has formed beneath It is likely that much of the moraines and outwash developed structures. Underlying gravels, which With increasing rainfall and elevation, Ohakune podocarp-broadleaf forest on flat and rolling upland terraces have an accretion of aeolian material on the become more compact with depth, have thin brown series grades into Pokaka series which has a thin surfaces, on high terraces, on toeslopes bordering surface. In other parts of the region, particularly on or dark brown humus stains. Most of these soils are layer of Taupo Pumice in the topsoil. Where Taupo moderately steep land, and on stable slopes within the outwash terraces, it is also likely that deflation still under a fern and scrub vegetation. Pumice overlies the andesitic ash in drier locations moderately steep topography. south and south-east of Mt Ruapehu, Ohakune has removed fine material from the exposed series grades into Moawhango series. Moawhango series occurs under a mean annual surfaces. Te Anau series rainfall ranging between 1150 mm and 1550 mm and Rainfall in the region ranges between 900 mm and Pokaka series 0ccurs within Waimarino County is moderately leached. Profiles have black, sandy 1600 mm, increasing to an estimated 2000 mm in the Te Anau series is developed largely on the and in the southern parts of Taumarunui County. It textured, friable A horizons with crumb and was first identified by N.Z. Soil Bureau (1954) and north, and is fairly evenly distributed throughout the younger moraines in the Te Anau Basin but is also granular structure, containing many pumice frag recognised on parts of the older moraines (Ramparts later by Wilde (1977). year. ments; overlying yellowish brown to dark yellowish Formation) overlooking the lake. Topography is Pokaka series occurs on the lower southern and brown, firm, silt loam and day loam textured B Pre-European vegetation comprised scrub and rolling to hilly, and in general the ground surface is western slopes of Mt Ruapehu and on upland horizons with blocky structure; on older andesitic fern over much of the area with tall tussock very uneven. The selies tends to be somewhat plateau and hill country south-west of National Park ashes. grassland adjacent. Beech forest predominated in variable, particularly on steeper slopes. However, it the high rainfall area to the north and on the western at elevations between 600 and 900 m. It has formed With increasing rainfall and elevation, Moa is characterised by a weakly weathered compacted side of the lakes. from more than 50 cm of andesitic ash (Tongariro whango series grades eastwards into Titapu series. sub-solum of gravels or gravelly sand at between 40- Ash) overlain by a very thin layer of Taupo Pumice The General Survey of the Soils of the South 50 cm, in sharp contrast to the brown or dark brown Titapu series occurs on the top and higher western ( <15 cm), on flat to rolling sites and on moderately Island, New Zealand (N .z. Soil Bureau 1968) solum. slopes of the Kaimanawa Ranges, between eleva steep stable slopes. included the yellow-brown loams in three soil sets: tions of 1100 m and 1400 m, under a mean annual Topsoils are black to dark brown silt loams or Monowai (11 250 ha), Te Anau (11 660 ha) and Pokaka series occurs under a mean annual rainfall rainfall of between 1250 mm and 1550 mm. It has sandy loams, commonly stony, with a soft, friable, Dunton (39 790 ha). More recent investigations exceeding 2000 mm and is very strongly leached. formed beneath tussock grassland and herbfield, granular and crumb structure. Subsoils are dark (O'Byrne in prep.) have further characterised these Profiles have dark brown and dark reddish brown, from a thin layer ( <15 cm) of Taupo Pumice over brown to strong brown, friable, stony silt loam or soils. All the soils are strongly to very strongly friable, sandy textured A horizons with weak andesitic ash, on rolling surfaces and on stable, stony sandy loams with weak structures. The base of leached, and subsoils in particular give strong structure; overlying friable, dark brown to strong moderately steep slopes. the horizon is usually marked by a thin dark reddish brown sandy or silty textured Bs horizons, also with positive reaction to the sodium fluoride test. brown humus band and associated root mat, resting Titapu series is similar to Moawhango series but is weak structure, and showing distinct Fe and clay Soils developed on outwash terrace gravels on greyish brown to pale olive brown massive and coarser textured. Profiles have black, sandy coatings; on friable to firm, dark brown to yellowish include the Monowai and Patience series, those on compact gravels. Since the 1950s most of the area textured, friable A horizons containing pumice brown silty textured colour B horizons, also with morainic deposits include Te Anau, Retford and where Te Anau series occurs has been developed for fragments; over yellowish brown and dark brown weakly developed structure; on yellowish brown to Dunton series. pastoral use. olive brown, firm, structureless, silty textured C sandy loams with bJocky structure. horizons. Thicknesses of ash over bedrock vary In the extreme north of the Wanganui Region on Retford series widely from 60 cm to depths exceeding 2 m where the northern uplands and dissected mountain lands, Monowai series old tephras are present. where the thicknesses of Taupo Pumice exceed Retford series has developed on the moraines in 15 cm, Moawhango and Titapu series grade into Monowai series is extensive on the broad flat Moawhango series has formed throughout the the high rainfall region to the north of Te Anau yellow-brown pumice soils and composite yellow outwash terraces in the Te Anau Basin and near cooler northern uplands of the Wanganui Region under a predominant scrub and fem vegetation. It is brown pumice soils on yellow-brown loams Lake Monowai. It is dominantly shallow to very where rainfall is somewhat lower than for Ohakune somewhat paler in colour than Te Anau series and is (Taraurau, Waiouru, and Ngamatea series). Where shallow and stony. Colours are brown or strong series and where a thin layer ( <15 cm) of Taupo much stonier in the upper horizons. Topsoils are very young andesitic ash (Ngauruhoe Ash) overlies brown throughout the profile, and this is attributable Pumice overlies the andesitic ash. The series was dark brown stony loams or gritty silt loams with Taupo Pumice, recent soils from volcanic ash and to the illuvial humus and iron material coating the first identified by N.Z. Soil Bureau (1954) and later stones and have a fine nut structure. Under forests, recent soils over yellow-brown pumice soils occur gravels. Topsoils are black to dark reddish brown silt by Campbell (1978). topsoils are very shallow. B horizons are yellowish (Ngauruhoe and Waimarino series). loams or sandy loams with a soft, friable, granular Moawhango series occurs between elevations of and crumb structure, and a varying proportion of brown to strong brown stony sandy loams or stony well rounded stones. silt loams with weak structures. Humus coatings may be prominent, and in places there are thin Subsoils have a silt loam to loamy sand matrix discontinuous iron pans. Underlying are light filling interstices between well rounded stones of brownish grey or greyish brown compact gravels. varying sizes (up to about 20 cm diameter). In most SOUTHLAND YELLOWmBROWN LOAMS places they are weakly or moderately cemented. Humus/iron coatings extend through the matrix and Dunton series gravels with decreasing intensity to depths of over J.G. Bruce, Soil Survey Office, D.S.l.R., Gore 1 m. Dunton series covers the largest area of the Southland yellow-brown loams and is imprecisely known. It is developed on strongly dissected older Soils in the South Island assigned to the yellow The soils are developed on glacial moraines and Patience series moraines under predominantly beech forest in the brown loam soil group are restricted to the western outwash gravels derived from rocks of the Fiordland higher rainfall. areas, and is podzolised. regions of Southland, adjacent to Fiordland. They complex which includes granite, gneiss, and diorite, Patience series occurs on undulating and easy cover an area of some 62 700 ha (0.5% of the South with additions of tuffaceous sandstones and basic rolling kame terraces along the eastern shores of The surface usually carries a dark or dusky red Island). The principal occurrence is in the Te Anau volcanic rocks from sources further east and north. lake Te Anau. It has considerably more fine peat or peaty litter which may be 20 to 25 cm thick. Basin near Lakes Te Anau and Manapouri, with In many places on the moraines the gravels are material in the solum and in general is darker in Underlying is a thin AE horizon of friable, peaty smaller occurrences in the Waiau River Valley near capped by varying thin to moderately thick lenses of Colour than Monowai series. Illuvial humus and iron sandy loam or silt loam, with a soft granular the outlet of Lake Monowai. firm sandy silt. The outwash gravels are well are also more prominent. Topsoils have dark greyish structure, and containing bleached sand grains. 41 40
YELLOW-BROWN COMPOSITES Associated with Dunton series are some soils in classification system (Raeside 1956) as they do have which an E horizon can be separated where the base an affinity with the upland and high country yell<:w of the A horizon pales. brown earths, apart from the deep brown coloratlon of the solum. Subsoils are brown to dark yellowish brown stony sandy loams which become paler with de~th. Humus The arrival of Soil Taxonomy (Soil Survey Staff staining on structural faces .and ~tones is common 1975) on the New Zealand scene has thrown sc:'me YELLOW-BROWN LOAM COMPOSITES AND INTERGRADES KING and thin, discontinuous, bnttle i7on pans may be light on the problem, howev~r. Under the Amenca? present. Underlying gravels are firm and co~p~ct, system these soils merge mto the Spodosol soil COUNTRY and in places have yellowish brown humus stammg. order, or may even be Inceptisols marginal t? These soils are largely unused. Spodosols, rather than fall within the proposed soil W.C. Rijkse, Soil Bureau, D.S.I.R., Rotorua There has been controversy as to the placement ~f order of Andisols. these 'yellow-brown loams' in the New Zealand sod INTRODUCTION weathered Tertiary rock. As for composite yellow brown pumice soils on yellow-brown loams, one of The Concise Oxford Dictionary defines composite the main criteria is that the B horizon extends across as something made up of various parts. There is no the boundary line of the two parent materials. In definition of an intergrade but this word as a soil mapping these areas, soil complexes are used, term, has a feeling of a slow change. Therefore mostly double symbolled with one major component composite tends to be used in soils made up of of composite yellow-brown loams or composite layered parent materials of a different age or origin, yellow-brown earths (Hiwi series, Onaio series) and whereas intergrades are used for soils that occur in the other major component of related yellow-brown between two soil groups generally comprising a loams or yellow-brown earths, indicating a patchy gradual change. cover of weathered tephra overlying weathered Tertiary material.
COMPOSITE YELLOW-BROWN PUMICE SOILS The pattern is even more complex on steep slopes, ON YELLOW-BROWN LOAMS and steepland soils are often related to more than one soil group (e.g. related to yellow-brown loams Yellow-brown loams do not intergrade towards and composite soils). the yellow-brown pumice soils. Instead they form composite soils whereby thin younger tephra such as Taupo Pumice overlies weathered rhyolitic or andesitic tephra (Fig. 1). A soil is a composite soil if the B horizon has developed overlapping both the INTERGR.ADES TOWARDS PODZOLS younger relatively weakly weathered tephra and weathered tephra (Rijkse 1974). Generally this The transition of yellow-brown loams towards occurs in areas where, for example, the thickness of podzols is a gradual climatic one. Podzol processes Taupo Pumice is 10 to 50 cm. are poorly expressed in weathered tephra but This system worked well in the King Country depositions of iron and organic carbon occur as where Taupo Pumice overlying andesitic tephra coatings on peds in the B horizon. Horizon thins out from east to west (Kokomiko series, nomenclature with increased leaching is as follows: Waione series, Ongawhao series, Taumaranui Yellow-brown loam Podzolised Podzol series, Tarangimotu series, Mapara series, Taurewa yellow-brown loam series and Kakaramea series). The problem of A A A patchy occurrence of any of the parent materials is (B) B1e A1 overcome by naming the soils in separate series and C (B) Bhte mapping soil complexes, using double or even triple c Bre (B) symbols, with the most frequently occurring soil c named first. Thus Kokomiko hill soils are mapped The soil 'in between' the yellow-brown loam and together with Ongarue hill soils (KorH + OgH). the podzol is classed as a podzolised yellow-brown The Kokomiko series is a composite yellow-brown loam with degrees of podzolisation expressed as pumice soil on yellow-brown loam, and Ongarue weak, moderate and strong. These terms have not series is a yellow-brown loam. This indicates that in been defined, mainly because of poor expression of that area a thin layer of Taupo Pumice occurs but podzol features in weathered tephra. An additional locally it is patchy. difficulty in the King Country is that where podzols are expected to occur (areas with high annual COMPOSITE YELLOW-BROWN LOAMS ON rainfall at high altitudes) Taupo Pumice is thicker, so YELLOW-BROWN EARTHS that yellow-brown loams grade into podzolised composite soils and podzolised yellow-brown Soils are classed as composite yellow-brown loams pumice soils. The podzols of the King Country tend on yellow-brown earths in areas where the total to have A, A 2 , Bhe horizons developed in Taupo tephra layer thins out to less than 50 cm overlying Pumice. 43. 42
THE BOUNDARY BETWEEN YELLOW-BROWN LOAMS AND YELLOW-BROWN EARTHS: AN EXAMPLE FROM DANNEVIRKE AREA, SOUTHERN HAWKE'S BAY
B.R. D.S.I.R., Havelock North
The soil map of the North Island, at 1:1 OOO OOO . Dannevirke soil set scale published in 1963 and accompanying Soil These soils are formed from andesitic ash mixed Bureau Bulletin 26 (N.Z. Soil Bureau 1968), shows with varying amounts of loess. Aokautere Ash (a the Dannevirke-Kopua and Matamau-Kopua distinctive rhyolitic ash, dated 20 OOO years B.P.) is Associations as intergrades between central yellow recognisable as a layer within the profile at a depth brown earths and central yellow-brown loams. varying from 60 cm to 130 cm. These soils o~cur on 0"' Recent larger scale mapping in the Dannevirke area N higher terraces which probably correlate with the '"O has looked at these units in more detail and the 0 Tokomaru and Milson terraces in the Manawatu. 0.. resulting subdivision provides an excellent oppor '"O They have a loamy texture throughou~, but hav~ a ~ <( c tunity to look at the properties of soils spanning the ::J "' lower bulk density and stronger sodmm fluonde a::: "' range. 0 I -s.... reaction in the upper part of the profile. > 0.. "'. Dannevirke 1 medial 9 z I CJ) (Soil Survey Staff 1975). Dannevirke 2 medial over loamy 1 I I- .!!l _J .§ Dannevirke 3 loamy 16, 2 ~ 3:I < Yellow-brown loams have been loosely defined as 01- l.U CJ) 5000 years). 0 a::: a::: s Series within the set (distinguished by taxonomic _J 3: ::; They have a loamy texture with a greasy feel, low classification, according to Soil Survey Staff, 1975 ~L5 0. 3 z c bulk density ( <0.9 Mg/m ) and give a positive and Andisol proposals of G. Smith, 1978. These z ~ reaction with the sodium fluoride field test. In the 3: 0.... units could also be classed as families as there is no ~~ 0 .!i' Dannevirke area the parent material is a mixture of further subdivision below family level): ~ ---11\P"-!O -co () ~ andesitic ash and greywacke-derived sediments _, a::: a::: .9 a::: ";:) m i.u m co - >. deposited either as loess or alluvium. During A Typic Hapludand, medial, mesic 9 )- I I I 0 mapping, the soils were subdivided first into sets or Umbric Vitrandept, medial, mesic l.U 3: 3: 3: .s using parent material as a distinguishing criterion, B Typic Hapludand, medial over loamy, mixed, t::o 0 cOJ) (/) _J _J () and then into phases using soil textures and particle 1 9 _J :a mesic _J O_i .... size modifiers. These modifiers are terms describing l.U j::: "'OJ) or Typic Vitrandept, medial over loamy, mixed, LU a.. l.U <( a combination of particle size and mineralogy and >- ::J "' mesic >- ~>- a::: s are more appropriate than texture terms in our 0 0 I .9"' C Umbric Dystrochrept, fine silty, mixed, mesic 16 () >- 0.. volcanic ash soils. (See footnote p.29 by Purdie, this LU LU c D Typic Haplumbrept, fine silty, mixed, rnesic 2 I ~ volume, for an elaboration of the term 'medial' as () a::: I- ....0 .0 used here) . ~ ea::: o ~ .9 The sets were also subdivided strictly according to ";:) Kopua soil set ~ ffiO~ :>- Soil Taxonomy (Soil Survey Staff 1975) and the I l.U ..... results of this subdivision have been called series . These soils are formed from mixed andesitic ash I- c .. (At present there is only one series per family). The and greywacke alluvium overlying greywacke :I"' L5 z OJ) soil sets and their subdivision are as follows: gravels. (Odd stones occur throughout the profile). <( ~ 3: Aokautere Ash is not recognisable within the Matamau soil set profile. These soils occur on the lower terraces which probably correlate with the Ohakea Terrace These soils are formed from loess with very little <( in the Manawatu. They have a low bulk density of volcanic ash. Either no ash was ever deposited on the fine earth fraction in the layers overlying the :::> the surface, or it was deposited and subsequent!y gravels and a moderate to strong fluoride reaction in eroded before the present soil formed. These soils all horizons. show no andic properties. (No reaction with sodium 3 fluoride, dry bulk density >1.0 Mg/m ). They are Phases within the set, and distinguishing features: probably Typic Dystrochrepts and/or Typic Profile no. Haplohumults of a fine silty, mixed, mesic family in Table 1 (no analyses available). Kopua 1 <10% stones v/v in the upper part of the profile 18 1Phases are mapping units significant to land use. They can be Kopua2 > 10% stones v/v in the upper part of the subdivisions of any category in the classification and are used here profile 7,14 to subdivide soil sets. 45. 44
mapping units (phases) and taxonomic units (series) define the limits of the yellow-brown loam Series within the set: sandy-skeletal, mixed, mesic 14 or Typic Vitrandept, medial-skeletal over can be arranged within the New Zealand genetic groupings. The ones that do this best are the family E Typic Hapludand, medial over sandy-skeletal, sandy-skeletal, mixed, mesic classification system as shown in Table 2. particle size classes or their modifiers that are used mixed, mesic 7, 18 as differentiae for mineral soils. Applying these we or Typic Vitrandept, medial over sandy-skeletal, Examples of profiles within each set and series are arrive at the following definitions. listed and some of their morphological, physical and Table 2 N.Z. genetic classification of soil mapping mixed, mesic Yellow brown loams. Soils where the family F Typic Hapludand, medial-skeletal over chemical properties are given in Table 1. The soil units and soil taxonomic units particle size modifier is medial. Table 1 Abbreviated data from profile descriptiems and analyses Soil group Mapping unit Taxonomic unit Yellow-brown loam composites. Soils that have contrasting particle size classes with the upper Yellow-brown loam Dannevirke 1 A one being medial. Stones Dey 15 bar water p t :j: Yellow-brown loam composite Dannevirke 2 B Yellow-brown loam intergrades. Soils where the Profile pH retent· Vari. BS c Kopua 1 E no. Location Hori· Depth Colour Consist- (% v/v) bulk W% family particle size is not medial, but many of the ence density field air NaF ion charge Kopua 2 EF (rainfall NZMSl zon (%) properties required to meet the medial definition (T/m3) moist dry (%) (%) (%) Yellow-brown loam intergrade Dannevirke 3 CD mm) (cm) Yellow-brown earth Matamau set are present to some degree. 11.0 Other groups. Soils where the family particle size 0-20 lOYR 3/3 friable 0 0.63 38.5 27.6 9.9 96 84 38 1 N145 A 2.4 is not medial and none of the properties required 20-51 lOYR 5/6 friable 0 0.55 53.5 15.4 9.6 99 88 39 (2000) 631 705 Bw 40 1.8 51-70 0 9.5 99 87 to meet the medial definition are present to any B-C 1.4 This arrangement suggests that some of the 70-100 lOYR 5/4 firm 0 1.02 32.9 14.7 9.8 97 90 28 significant degree. 2C criteria and definitions of Taxonomy may be used to 3C 100-120 2.5YR 5/4 v. firm >35
17.9 9.1 80 59 81 5.1 2 Nl45 A 0-28 lOYR 3/3 friable 0 0.90 22.8 9.2 70 59 81 1.3 (1270) 563 586 Bwl 28-47 lOYR 5/6 friable 0 0.89 22.2 11.5 43 52 86 0.6 Bw2 47-60 lOYR 515 firm 0 1.43 16.8 10.2 8.7 YELLOW-BROWN LOAM TO YELLOW-BROWN EARTH INTERGRADES IN 37 50 88 0.4 Bw3 60-81 lOYR 5/4 firm 0 1.50 19.7 10.8 8.4 47 0.5 Bw4 81-101 lOYR 5/6 firm 0 1.32 26.5 13.6 8.5 54 64 SOUTHLAND 2Cl 101-112 lOYR 517 firm 0 0.98 2C2* 112-125 lOYR 515 friable 0 3C 125 + lOYR 5/4 firm 0 J.G. Bruce, Soil Bureau, D.S.I.R., Gore
94 88 23 10.8 7 N145 A 0-20 7 .5YR 3/3 friable 18 0.55 39.7 26.9 9.9 20-32 7 .5YR 4/4 friable 24 41.1 21.2 10.1 98 93 15 6.0 Soils belonging to the Drummond and Glenelg rounded and subrounded gravels in a gritty matrix 517 609 Bwl 17 4.6 Bw2 32-64 7 .5YR 4/5 friable 46 31.8 21.3 10.1 99 93 sets (N .Z. Soil Bureau 1968) were previously are encountered at depths of 30 cm to 40 cm. 2Cl 64-84 7 .5YR 3/4 >35 considered to be brown granular loam to yellow 2C2 84-95 2.5Y 6/4 >35 brown earth intergrades. During recent field work in 95-105 lOYR 3/3 >35 2Cs3 Wallace County (O'Bryne in prep.), the status of Glenelg series 27.7 9.5 94 83 32 11.6 these soils was examined and they are now 9 N145 A 0-15 lOYR 3/3 friable 0 0.71 39.7 81 42 5.7 513 263 AB 15-25 lOYR 3/3 friable 0 44.3 20.5 9.6 98 considered to be yellow-brown loam to yellow Glenelg series is a shallow, and in places stony, 84 40 3.4 Bwl 25-40 lOYR 4/4 firm 0 0.72 43.6 17.7 9.6 98 brown earth intergrades. New soil series have been soil occurring on intermediate terraces and fans in 80 52 1.5 Bw2 40-65 lOYR 515 firm 0 0.83 35.2 15.4 9.6 97 the valleys of the Waiau River, the upper Oreti 94 77 59 1.0 separated from the original soil sets and their Bw3 65-82 lOYR 5/6 firm 0 0.97 31.2 14.1 9.5 River, and in the Hamilton Burn and adjacent friable 0 0.79 31.4 12.8 9.7 97 79 55 1.0 definition has been tightened. Bw4 82-95 lOYR 515 catchments of the Aparima River. 2C 95-110* lOYR 6/6 firm 0 0.71 3C 110-150 2.5Y 5/4 firm 0 0.90 D:rmmnond series Profiles have dark brown, friable, stony silt loam 9.7 90 73 59 7.4 topsoils on yellowish brown, friable, stony silt loam 14 N145 A 0-20 lOYR 3/3 friable 13 0.80 20.3 19.9 10.0 96 90 27 4.1 B horizons over weakly weathered fan gravels. (1200) 546 501 Bwl 20-41 lOYR 3/3 friable 38 0.86 22.0 16.4 Drummond series occurs on the broad fan-shaped 89 24 2Cl 41-55 lOYR 4/4 loose 47 4.8 3.6 8.8 39 former flood plain (Drummond Fan) of the Aparima Humus illuvial material extends well into the 61 5.0 4.2 8.9 42 89 18 2C2 55-83 lOYR 3/4 firm River between Otautau and the Oreti River. In gravels. The profiles are similar to those of Monowai 83-115 lOYR 3/4 firm 70 4.3 3.7 8.1 33 83 22 series but are less compacted. 2C3 115-150 lOYR 4/3 loose >35 addition, there are some smaller occurrences in the lower reaches of the Waiau River and the 70 4.2 16 N149 A 0-24 lOYR 3/3 friable 0 1.02 19.3 15.2 Waimatuku Stream. They are developed on 72 56 1.7 Braxton series (1150) 378 408 Bwl 24-50 lOYR 5/4 firm 0 1.12 23.2 11.8 9.3 80 tuffaceous greywacke alluvium with some additions Bw2 50-85 lOYR 5/6 friable 0 from other sources. 2Cl 85-100* lOYR 5/8 friable 0 Braxton series (formerly included m both 3C 100+ lOYR 5/4 firm 0 Topsoils are deep, friable, dark brown silt loams Drummond and Glenelg soil sets) has a somewhat With fine nut and granular structure; on yellowish patchy distribution on intermediate terraces and fans 44 8.2 18 N145 A 0-22 lOYR 3/3 friable 8 0.73 28.0 22.0 9.6 93 80 brown to strong brown, friable, silt loam to silty clay in the same areas as both Drummond and Glenelg 9.8 97 89 28 3.2 (1525) 480 527 Bwl 22-45 lOYR 515 friable 8 0.72 35.4 17.7 loam subsoils. Structures in the subsoil are only series. 45-70 lOYR 516 firm 5 0.94 28.0 14.9 9.7 93 89 26 3.1 Bw2 Weakly to moderately developed. Underlying are B-C 70-82 lOYR 5/6 It is a poorly drained intergrade between yellow 2C 82-120 2.5Y 4/2 loose >35 Yellowish brown, compact, silty clay loams with few brown loams and yellow-brown earths and occurs mottles. further towards the toe and lower central part of * Aokautere Ash Associated with the deep profiles there are fans, or is closely associated with either Drummond tVariable charge. The amount of variable charge is calculated by substracting the bases + exchangeable Al from the CEC shallow Drummond profiles (formerly included with or Glenelg series in marked braided patterns in obtained with BaC12 at pH 8.2 (CEC8.2). Glenelg set) which occur further towards the apex central and upper parts of fans. CEC - (bases+ exchangeable Al) x 8 2 100 Variable charge % · CEC a_nd central parts of the Drummond Fan. These are Braxton profiles have dark brown, friable, silt 8.2 similar to the deeper Drummond profiles except that :j:Base saturation. Determined by ammonium acetate method at pH 7.0. loam topsails with well developed nut structure; on 47 46
5. deep pale grey or greyish br<;>wn, firm, silty clay undulating and easy rolling terrace surfaces, lateral loams with few to many promment mottles. Depth to the older moraines. It is developed on gravels of to underlying gravels varies but is usually b.etween mixed provenance, dominated by indurated sand 60 cm and 1 m. Deep profiles of Drummond series, stone with smaller amounts of diorite, gneiss, and SAND MINERALOGY OF NORTH ISLAND YELLOW-BROWN LOAMS shallow profiles of Drummond series and Braxton granite. In most places there is a thin covering of series form a repetitive catenary sequence both loess derived from similar rock types. R.B. Stewart, Department of Soil Science, Massey University, Palmerston North across and down the Drummond Fan. Profiles have dark brown, friable, silt loam or sandy loam topsoils with weak nut sti:ucture; . on potassium feldspar (sanidine). Plagioclase feldspar brownish yellow to light olive brown, fnable, gntty INTRODUCTION Wbitestone series silt loam subsoils that are weakly structured. grains may also be strongly zoned but are more sodic in composition. Quartz may also occur as a primary Underlying are compact, weakly weathered gravels The yellow-brown loams are predominantly Whitestone series (formerly included in Lynwood component in rhyolitic tephras. soil set) occurs in the Whitestone Ri~er-Lynw<;>od in a sandy matrix. formed from andesitic ash. However, soils region of the Te Anau Basin on low to mtermedmte developed in distal deposits of rhyolitic ash also fulfil the requirements for a yellow-brown loam (Cowie, VOLCANIC GLASS this volume). Strictly, therefore, the sand mineral ogy of the soil will reflect that of the parent andesitic Volcanic glass forms a major component of most or rhyolitic ash(es) in which soil formation has tephras with a moderate to high silica content and occurred. In the North Island, distribution of yellow consequently glass forms a large part of the sand brown loams is largely restricted to regions in which fractions of many yellow-brown loams. Glasses of andesitic volcanism is predominant (e.g. Taranaki), different composition are usually distinguished by or peripheral to areas of rhyolitic volcanism (e.g. their refractive index (R.I.) (Wilcox 1965, Hodder Waikato). 1978), as this has been shown to be predominantly determined by silica content (Matthews 1951). The method is suitable for distinguishing glasses of MAFIC MINERALS sufficiently differing composition, such as rhyolite and andesite, but it must be remembered that the Mafic mineral assemblages have been used to refractive indices do not form discrete clusters within differentiate tephras, particularly those of rhyolitic each magma type. Rather, there is a continuous composition from the central North Island (Ewart inverse relationship between silica content and R.I. 1968, 1971, Kohn 1970, 1973). The mafic assemb Thus distinctions within, say, rhyolites may be lages are usually indicative of a particular centre difficult to make. However, by using precise only. The presence of abundant cummingtonite (a techniques, glasses of slightly differing R.I. may be calcic amphibole) has been used to indicate a source statistically separated from a mixed population in the Haroharo complex, located in the Okataina (Hodder 1978). Volcanic Centre (Ewart 1968) and aegirine has been used to identify the Tuhua Tephra, from Mayor Andesites often show evidence of a high degree of Island, in the Waikato-Coromandel region (Lowe et fractional crystallisation and the residual liquid may al. 1980). be sufficiently enriched in silica to approach a dacitic composition, making a distinction from a dacite on The chemical composition of titanomagnetites has the basis of R.I. difficult. also been used successfully to differentiate indi vidual tephras (Kohn 1970), and this may be Iron content and hydration also affect the R.I. of a applicable to andesitic tephras (Kohn & Neall 1973). volcanic glass <1.nd need to be taken into account However, in the soil-forming environment, biologi when making such measurements (Ross & Smith cal mixing is common in all but rapidly accumulating 1955, Hodder 1978). sites and the sand mineralogy is likely to reflect some mixing of the parent tephras. EFFECTS OF CONTAMINATION AND REDE POSITION FELSIC MINERALS The sand fractions of yellow-brown loams can Felsic minerals may also reflect compositional have significant amounts of non-volcanic, quart variations in the parent tephras. This is shown in zofeldspathic material (Wilde 1974, Stewart et al. both the presence or absence of certain phases, such 1977). Ultimately, with a decreasing volcanic as quartz or potassium feldspar, and in composi component, these soils grade into yellow-brown tional variations within mineral groups, such as the earths and yellow-grey earths. There remains a plagioclase feldspars. Yell ow-brown loams problem of defining the boundaries between these developed in andesitic parent materials contain soil groups in terms of parent material content. In little, and usually no, quartz in their sand fractions. mixed provenance situations, the sand fraction Plagioclase feldspar often occurs as markedly zoned contains minerals from widely differing origins, crystals with a mean composition usually of including volcanic, plutonic, metamorphic and andesine. Potassium feldspar is also rare or absent. sedimentary rock types (Table 1). In contrast, the sand mineralogy of yellow-brown Parent materials of yellow-brown loams may also loams developed in rhyolitic materials often contains show evidence of redeposition to form 'tephra loess'. 48 49
Mafic minerals are more stable, although these IMOGOLITE AND ALLOPHANE Table 1 Sand mineralogy of an Egmont black loam too weather with time and in suitable weathering diameter (Wada 1977). Allophane spherules with a molar ratio close to Al/Si 2.0 appear to be composed environments. For the more common mafic minerals Jxnogolite is made up of hollow tubes up to 1 µm .. the order of stability appears to be: of distorted imogolite-like segments (Parfitt & i::: ~ in length, of external diameter 2_.0-2.4 nm, and has Henmi 1980) and a cross-section of a spherule is ] l ., ., ~ titanomagnetite/magnetite > hypersthene > horn j .: :!:! s:: the ideal formula (OH)3Al20 3S10H (~ada 1977). .&:l ~ thought to be similar to that of imogolite (Fig. 1) .!! "Q ~ = ~ blende > augite > biotite The tubes often occur in bundles which, when m •t j ~ 1. ·z except that the diameter is approximately double, <'II I i ~ er .. 1i~le This is a generalised order of stability and would be dose-packed hexagonal array, give a characteristic and defects or pores exist in the wall of the spherule. Tephra affected by both the weathering environment and X-ray diffraction pattern. The wall of the tube Phosphate adsorption and infrared spectroscopy (0-70 cm) mineral composition. consists of a curled gibbsite sheet with isolated studies (Parfitt & Henmi 1980) suggest that there are 63 µm-20 µm s s s a c tr a s R o SiOH tetrahedra on the inner surface. A cross about ten defects per spherule, but about 95% of the 125 µm-63 µm c s s a s a s R Feldspar minerals also weather more slowly than se~tion of the tube is shown in Fig. 1. Imogolite is wall has no broken bonds. Allophane with Al/Si Tephric loess glass. Calcic plagioclases are more susceptible to usually present in only small amounts in most (70-130 cm) molar ratio of 2.0 provides a reference point within weathering than the alkali feldspars. Quartz, since it volcanic ash soils in New Zealand. 63 f.llm.--20 µm s s s a tr a s c s s is usually only mildly affected by weathering the allophane series and it is appropriate to 125 µm-63 µm c s s a tr c R c s s processes in most environments, becomes residually Allophane has been defined as a series of summarise its properties: it is a naturally occurring concentrated as the other primary minerals are naturally occurring hydrous aluminosilicate clays, aluminosilicate clay of molar ratio Al/Si 2.0, with *Data from R.B. Stewart, unpublished, expressed as % of size removed by solution or reduced to finer particle characterised by short-range order and by the short-range order, having the proto-imogolite fraction. sizes by decomposition. Thus if quartz were predominance of Si-0-Al bonds, and it appears to infrared spectrum and unit particles which appear to Key: A=>50%; a=30-50%; C=l0-29%; c=S-9%; S=l-4%; originally present, the sand fraction becomes be made of up hollow spherules 3.5-5.0 nm in be hollow spherules, 3.5-5.0 nm external diameter. R= THECLAYMINERALOGYOFYELLOW-BROWNLOAMSOILS R.L. Parfitt and M. Russell, Soil Bureau, D.S.I.R., Lower Hutt and J.H. Kirkman, Department of Soil Science, Massey University, Prumerston North INTRODUCTION of hollow spherules with short-range order and this may mean that many earlier concepts will have to be Yellow-brown loam soils have distinctive physical revised. In addition to allophane and imogolite, and chemical properties which are largely deter other minerals which occur in yellow-brown loam mined by allophane and imogolite in the clay clay fractions, often only in small amounts, are fraction. Until recently allophane was thought to be halloysite, gibbsite, opaline silica and silica flakes, an amorphous gel, lacking even short-range order, glass, goethite, ferrihydrite, quartz, cristobalite and which links soil particles together in an open feldspar. Chlorite may also be present and is thought F. 1 Th cross-section of an imogolite tube. The view is down the tube axis showing atom positions in detail for all ten unit cells. Each framework conferring a low bulk density to soils. to be derived from loessial additions to these soils. aguire e · h. f Th · f · l Palagonite and hydrous feldspar are terms no longer silicon tetrahedron is isolated and Si-0-Si bonds do not occur although they may appear to be present m t is 1gure. . e s1zes_o c1rc es New techniques have shown that allophane consists illustrating the atoms are arbitrary, the arcs of circles show the bond lengths of the inner and outer OH thus demarcating the mner and used to describe clay components in these soils. outer surfaces of the tube; the outside diameter is 2.14 nm, inside diameter 0.64 nm. 50 51 The allophane series includes materials of Al/Si material in soils, and Higashi and Ikeda (1974) and molar ratios extending from 1.0 to 2.5. Parfitt et al. Wada (1977) showed that the method could be used (1980) showed that an allophane sample with an to dissolve allophane in volcanic ash soils selectively Al/Si molar ratio close to 1.0 gave an infrared in the presence of crystalline clays. Russell et al. 0 0 spectrum with bands at 450, 580, 680 and 1020 cm-1, (1981) used the percent Al dissolved by acid oxalate N indicating a significant degree of polymerisation of to determine the allophane content of the clay constituent silica. It was suggested that this silica fractions of samples of an Egmont black loam using rich allophane consisted of hollow spherules either proto-imogolite allophane (sample PC 963 Table 1) with proto-imogolite walls having additional silica as a standard. The results (Table 1) were in good polymerised on the inner surface or with gibbsitic agreement with those obtained by the infrared walls having silica polymerised on the outer surface. spectroscopic method of Farmer et al. (1977) for the determination of proto-imogolite, and applied to the The infrared spectrum of an allophane with Al/Si same samples. The acid oxalate method can molar ratio of 1.23 is presented in Fig. 2. This therefore be used successfully when the Al/Si molar sample appears to be a mixture of two materials: (a) 0 ratio of the allophane is dose to 2.0, i.e. when the 0 proto-imogolite allophane with bands at 348, 430, allophane has a proto-imogolite structure. Samples 0 500, 580, 680 and 950 cm-1 and (b) silica-rich with higher Al/Si molar ratios, on acid oxalate -M """ allophane (Al/Si molar ratio 1.0) with bands at 470, treatment, gave results which did not show such """ ,.....0 0 580, 680 and 1040 cm-1. Using a series of good agreement with the infrared method, possibly £ allophanes, Parfitt et al. (1980) showed that the """ because of the high organic matter levels. "Oc: 1040 cm-1 polymerised silica band increased and the '" 950 cm-1 proto-imogolite band decreased as the "Oc:"' Al/Si molar ratio changed from 2.0 to 1.0 suggesting PROPERTIES OF ALLOPHANE .D'" that the allophanes are mixtures of the two 0 "':i:: -oo ~o structures proto-imogolite (Al/Si molar ratio 2.0) !.!) ,...; The high phosphate retention values of yellow 0 - and silica-rich units (Al/Si molar ratio 1.0). Rather 0 .9 < brown loam soils are usually ascribed to the high co '§ :i than two distinct bands, a series with intermediate allophane content. Support for this suggestion .... 0 structures would have given a single infrared comes from the correlations between phosphate 0(/)'" ·~ absorption band which would have shifted gradually I s > retention and Tamm Al values (Saunders 1965), and 0" E Vi from 950 to 1020 cm -1 as the Al/Si molar ratio 0 (.) ;::, s the good relationship between Tamm Al and 00 "... ..c:. increased. co > ~ allophane content in volcanic ash soils. The sites - (.) ..c: 0::; c: where phosphate is adsorbed on allophane are Cl) ·~- "O- 15 :::i !l ..... thought to be the defects in the spherules where er QUANTITATIVE DETERMINATION OF Cl) §"'"u :J 0 single Al-OH groups, or substituting Fe-OH groups, ...... c:: ~ 0 ALLOPHANE LI... 0. >in are exposed (Parfitt & Henmi 1980), and it has been 0 ",..., 0 ~]S estimated that each allophane spherule can strongly 0 Acid oxalate (Tamm reagent) has been used for '""O adsorb six phosphate ions. Surface horizons of 00 0 many years to estimate the amount of amorphous " es 0""c:i"' 1l u ..c:::~ 1 " "' Table 1 Chemical analyses of Egmont samples ~·~- '6 "O "O .... " "co a «I~ ~ ~.9 Acid oxalate extractable Proto-imog. Pyr11phooph11te ext. Cit.-dith.4 3 """'"" Al Si Fe Al/Si lillo~ allophrme Al .Si Fe Al Si Fe N~~ (%) (%) (%) M ratio (%) (%) (%) (%) (%) (%) (%) (%) ..... (/)'"'" (/) st....,~ 0 ..... ctl .D 0 f;&, ..._,..._, Clay 0 <2µ,m 0 PC 984/1 11.1 4.6 2.5 2.48 41 36 1.4 <::!" 2 16.8 6.6 3.6 2.50 61 67 1.3 0 3 18.9 9.0 4.2 2.17 69 82 0.7 4 19.1 10.0 4.1 1.98 70 72 0.8 4.3 1.5 5.7 5 18.5 9.8 4.2 1.97 68 82 0.7 2.9 0.7 5.0 6 12.9 7.3 3.7 1.83 47 54 0.6 PC 963 25.6 13.3 4.0 2.00 94 94 1.9 4.7 1.2 3.0 Whole soil <2 mm PC 984/1 3.6 1.8 0.9 2.13 13 0.8 0.07 0.26 0 2 4.7 2.0 1.2 2.44 18 0.6 0.07 0.18 0 3 5.2 2.3 1.4 2.38 20 0.4 0.07 0.07 N 4 5.4 2.5 1.4 2.27 21 0.5 0.08 0.08 5 5.4 2.9 1.6 1.92 21 0.4 0.08 0.06 6 2.1 1.0 1.7 1.96 8 0.3 0.07 0.07 7 2.8 1.4 0.8 2.00 10 0.2 0.07 0.05 UO!SSIWSUe.Jl 1Expressed on oven dry (150°C) basis 2Estimated from acid-oxalate %Al 3 Estimated from IR absorbance at 348 cm - 1 4Citrate-dithionite-bicarbonate extra-::table 52. 53 approximately 2000 years, and halloysite crystallises formed on mainly rhyolitic tephra with lesser yellow-brown loam soils adsorb less phosphate than under high rainfall, with silica leaching conditions in after a further 7000-8000 years. Andesitic glass, on andesit~c contributions, contains allophane and lower horizons (Russell et al. 1981), but it is not Taranaki, Al-rich (andesitic) glass rapidly weathers the other hand, weathers to allophane rapidly, balloy~1te, the proi:iorti~:ms of these minerals varying clear whether this is due to organic matter or ~o a persistent Al-rich allophane, and that halloysite usually within 300 years but the allophane persists accordmg to location m the profile. The andesitic previous phosphate additions blocking the adsorp is absent save where additions of rhyolitic glass have for at least 100 OOO years (Kirkman 1980b). Egm~nt, Stratford and Patua soils (Fig. 3) all occurred, or where feldspars have weathered to tion sites (Perrott 1978b). contam proto-imogolite allophane. tubular halloysite. Phosphate may also be adsorbed on other soil Soil factors additional to time are doubtless components in yellow-brown loam soils in addition WEATHERING STUDIES At present the evidence suggests that Al-rich influential in determining weathering pathways in to allophane. These include ferrihydrite, goethite, allophane with a proto-imogolite structure does not Until recently the weathering sequence glass tephra. Parfitt et al. (this volume) concluded that for gibbsite, and organically bound Al and Fe (Wada & usually alter to halloysite. This is to be expected the rhyoliti~ Kawakawa Tephra (20 OOO years B.P.) Gunjigake 1979). In addition to the rapid adsorption allophane-halloysite has been broadly accepted as since Si tetrahedra are thought to be located on the allophane mcreases and halloysite decreases as of phosphate by yellow-brown loam soils, there is operating in tephra and tephra-derived soils, and interior surface of the hollow allophane spherules rainfal~ changes from 1200 mm to 2600 mm (Table also a slower reaction (Russell et al. 1981). It has this sequence is explicit in Japanese literature (Wada largely_ as ~solat~d units with apices directed awa; 1977). The sequence is based on the observation that 2). 'f?~s conclusion is supported by the work on the from gibbs1te uruts, the reverse in fact of the kaolin been suggested by van Riemsdijk (1979) that on Al rhyoht1c Rotoehu Ash by Birrell et al. (1977) who surfaces this may involve the formation of a coating allophane forms rapidly in volcanic ash soils whereas ~tructurn. . Thus alteration to halloysite would showed t~at allophane levels increase significantly of taranakite, a potassium aluminium phosphate, halloysite often does not appear for at least 10 OOO mvolve 'nie allophane passing through a solution years after the ash has been laid down. Low when ramfall exceeds 1600 mm. Thus intense ~~ase, during which enrichment with polymerised which would require some disruption of allophane leaching of silica from rhyolitic tephra tends to structures, as has been observed by Rajan (1975b), allophane levels occur where halloysite levels are silica must take place, and Si tetrahedra must be ~erpetuate allophane and depress halloysite forma to provide the aluminium in the coating. high, giving the impression that allophane has reoriented with respect to gibbsite units. Thus weathered to halloysite. tion, presumably because of lower levels of halloysite would not be expected to occur in yellow The variable charge characteristic of allophane polymeric silica in solution. It is not surprising that brown loam soils in the absence of considerable In New Zealand, Fieldes (1955) suggested that the may also be ascribed to the single Al-OH and Fe ~nrichm~nt with polymerised silica. Rather, gibbsite sequence includes the additional stages of allophane OH groups which occur at defect sites in the is more hkely to form in strongly leached soils, as in B-allophane AB-allophane A. However, no evi allophane spherules where bonds such as Al-OH-Al Table 2 Percent allophane and halloysite in the fact has occurred for some tephras located in the Te dence for allophane A, AB or B was found by are broken. Variable charge arises from reactions of clay ( <2 µm) fraction of the Kawakawa Tephra Kuiti and Hamilton districts. Kirkman (1975) and now that the proto-imogolite groups such as Al-OH with H + and OH - as the pH and Rotehu Ash at four different locations structure is known to apply to much New Zealand In summary, the weathering of andesitic and changes: allophane, particularly that present in andesitic rhyolitic glass is characterised by loss of silica OH- tephra, the original data of Fieldes (1955) may be Soil Annual Kawakawa Tephra Rotpeim Ash (Kirkman & McHardy 1980) and the weathering ~ high pH reinterpreted. The Kaharoa soil (Fig. 3), formed on Rainfall allophane halloysite allophane halloysite products are largely determined by the Al/Si molar (%) (%) (%) (%) rhyolitic tephra, contains glass, opaline silica, and a (mm) ratio . of the original glass and the intensity of The charge on allophane with Al/Si molar ratio 2 silica-rich allophane, and this is supported by the leachmg. The andesitic parent tephras of yellow work of Kirkman (1975). The Tirau soil (Fig. 3), Kereone 1200 2 50 3 50 brown loam soils usually weather to Al-rich varies from - 20 meq/100 g at pH 8 to Tirau 1270 45 5 15 50 + 10 meq/100 g at pH 5, whereas on allophane with Ohaupo 1400 35 25 10 45 allophane, but crystallisation of halloysite is Al/Si molar ratio 1 it varies from - 50 meq/100 g at Mairoa 2600 70 N.D. 60 <1 norm~~ly r~s.tricted to those soils and tephras of pH 8 to a net charge close to 0 meq/100 g at pH 5 rhyohhc ongin where the annual rainfall is less than (Wada & Okamura 1977). N.D.-not determined 1600 mm (Birrell et al. 1977). Kaharoa HALLOYSITE In New Zealand tephras and tephra-derived soils, two morphological forms of halloysite have com monly been observed. The tubular form is usually present as short, fine tubes, many of which are Taupo sufficiently distorted to give the appearance of curled sheets. This form of halloysite probably Tirau crystallises only from weathering feldspar (Kirkman 1980a). Chunky barrel-shaped particles, possibly formed by a spiral mechanism (Kirkman 1977) have Egmont frequently been referred to in the literature as circular. ball-like or spherical halloysite. Such Stratford halloysite probably forms only from allophane which has weathered from rhyolitic glass. In andesitic Patua tephra, halloysite is not normally abundant. Frequently it is absent, or present only in small amount, and may appear as fine tubes only, or as fine tubes mixed with squat ellipsoids. The presence of squat ellipsoids in andesitic tephra and yellow brown loam soils can normally be taken as indicative 1200 1000 of addition of a small amount of rhyolitic glass, Frequency (cm - 1) probably originating from one or more of the major rhyolitic eruptions in the Central North Island, or Figure 3 Infrared spectra of some New Zealand fine clays fro!l1 from tephric loess derived from gullies, terraces or Fieldes & Claridge (1975). Recent evidence suggests the presen.ce marine benches. Kirkman (1975) showed that of opaline silica (0), volcanic glass (G), 'proto-imogohte allophane' (P), silica-rich allophane (S) and halloysite (H) · rhyolitic glass weathers to allophane over a period of 54 55 SOIL The yellow-brown loam group, as a whole, While this mobility of water is found in the yellow compares better with other soil groups in terms of brown loams at a tension (0.1 bar) dose to that the amount of water it can store at tensions small expected at field capacity, there are indications that enough for withdrawal by plants without significant it diminishes rapidly as tensions increase above that PHYSICAL PROPERTIES OF LOAMS effort, so that optimum growth is maintained during level. Six samples tested at both 0.1 and 0.2 the extraction. Such water is held in pores from 30 to bar showed a mean decrease of hydraulic conductiv Lower Hutt 3 µm in diameter, approximately, and the yellow ity over that range of tension to one sixth of its value brown loams have been shown to contain signific at 0.1 bar. Further rapid decreases of conductivity antly more pores of this size in the lower A and the B are to be expected at greater tensions, and at Soil Bureau data on the physical properties of the horizon. For most soil groups the volume of such and C horizons than most other New Zealand soil tensions of 1 bar or more the yellow-brown loams yellow-brown loams are derived f~om nine profiles pores decreases with increasing depth. groups (Gradwell 1978-Tables 3 to 6). When they may be no more conductive of water than most other in the Waikato area (mostly Horotm sandy loam and are fully wetted to field capacity nearly two fifths of New Zealand soils. The abundance of large pores to a considerable Ohaupo silt loam), five profiles in Taranaki and one the plant-available water present in the yellow depth in the yellow-brown loams promotes rapid brown loams is composed of this 'readily available profile of Karaka silt loam in South ~~ckland. Most drainage in these soils. The writer has dug sampling of these profiles are formed on andes1tlc ash but the water' (Gradwell 1976-Table 4; 1978-Tables 2 to SOIL TRAFFICABILITY pits in yellow-brown loams following a rainy night in Horotiu and Karaka soils are from ash resorted and 6). winter and found the soil throughout the profile free Yellow-brown loams have a good reputation for deposited by water. All profiles are in areas of highly from apparent wetness or stickiness and only moist resisting puddling under the wheels of farm productive pasture. in appearance. The mineral constitution of these TRANSMISSION OF WATER machinery or the feet of grazing animals in wet soils also helps to reduce stickiness. weather. Gradwell (1974) has reported experiments BASIC PHYSICAL PROPERTIES Another likely consequence of a large volume of on six undisturbed topsoils, representative of various pores between 30 and 3 µm in diameter is an Auckland soil groups, which throw some light on the STORAGE OF WATER It is not possible to provide precise data on the appreciable hydraulic conductivity in profiles specific characteristics that make yellow-brown particle size of yellow-brown loams, as the complete drained to field capacity. At field capacity pores loams resistant to deformation. Although the low The water contents of yellow-brown loams vary larger than 30 µm are likely to be drained and density of the yellow-brown loams tested led to dispersion of these soils in water has not so far ~een considerably but many of them are quite high. Most accomplished. Field textures are therefore the oest inoperative, and the hydraulic conductivity is initial deep penetration of a loaded piston into the values recorded are between 20 and 100% of dry provided by pores a little smaller than that size. well wetted soil, continuing applications of the source of information on particle size. The simplest weight. Much of the water is strongly retained, as measured property that distinguishes the yellow Actual measurements of the hydraulic conductivities piston produced less deep penetrations. After many seen in the frequent high values of wilting points for brown loams from most soil groups in the country is of subsoils after drainage to a tension of 0 .1 bar have overlapping applications the underlying soil still these soils. In many profiles the wilting points of their low dry bulk densities (Gradwell 1976-Table verified this prediction. Of several New Zealand soil contained appreciable air-filled pores following a subsoils considerably exceed those of the topsoils groups studied the yellow-brown loams were simulated drainage. Three zonal soils given to 4). The mean bulk density of the C horizpns of above them (Gradwell 1968, 1976) despite the eleven yellow-brown loams was 0.73 Mg/m. The amongst the most permeable, most conductivities breakdown under winter treading contained virtu contribution of soil organic matter to the retention measured on them exceeding 10-3 cm per hour ally no air. The persistence of large pores, which mean density of the A horizons of the same soils w~s of water. It is thought that the high water contents of virtually the same. The coarse, water-sorted Horotm (Gradwell 1979). The comparatively permeable drain readily, appears to be critical, as it leads to yellow-brown loams derive from their large contents sandy loam, not included in calculating the eobove nature of yellow-brown loams, mentioned above as compaction and increase of strength under traffic. In of allophane (Gradwell 1976). After air drying, th.e evident after rain, persists into a range of water addition, the water content of the yellow-brown means, was somewhat denser, but less so than most power of allophanic soils to retain water is other soils in New Zealand. Mean dry bulk densities contents a little drier than field capacity. This means loam in its original structural condition and at a considerably reduced (Gradwell & Birrell 1954- of the Horotiu soil were 0.87 Mg/m3 in the A that continued slow drainage to subsoils is likely to tension similar to that found at field capacity was 3 Table 4) and it seems possible that the topsoils ~f continue for some time after 'field capacity', as well below the lower plastic limit for the soil, in horizon and 0.90 Mg/m in the B and C horizons. some profiles have, at some stage of their Low soil densities favour the proliferation of roots, usually understood, has been attained. There is also contrast to the relations for the zonal soils. This agricultural history, experienced a severe drying that and inspections in profile pits do indicate a deep and a probability that water will be drawn up means that mechanical mixing of the yellow-brown has not occurred in the underlying subsoils. widespread root growth in yellow-brown loams that comparatively rapidly from soil underneath the loam at field capacity would not produce the plastic is interrupted only where the ash material ceases at Because of the high wilting points, the amounts of maximum depth of actively extracting roots and flow which appears to be most damaging to soil shallow depth and is succeeded by underlying sands water retained by most yellow-brown loams at augment the nominal available water capacity of the structure. or sedimentary rocks. tensions in the plant-available range do not equal the visible rooting zone in these soils. very high retentions of the yellow-brown pu~ice soils. The yellow-brown loams rank as only a htt!e PORE-SIZE DISTRIBUTIONS above average amongst New Zealand soil groups 1il capacity to store plant-available water. Their mean FACTORS AFFECTING 15-BAR WATER RETENTION IN YELLOW-BROWN LOAMS Associated with the low bulk densities of yellow estimated retention of 126 mm in the surface 76 cm brown loams are volumes of large-sized pores that of profile is significantly greater than the values for are consistently greater than those of several other three out of four zonal soil groups, formed from M.P. Tuohy, Soil Science Department, Massey University New Zealand soil groups for which comparable data sedimentary rocks or loess (Gradwell 1976-Table are available (Gradwell 1978). This exceptionally 4). There are, however, some indications of a Among the most distinguishing physical charac high content of large pores is very evident in the B differentiation inside the yellow-brown loam group teristics of yellow-brown loams are the high 15-bar The measurement of 15-bar water contents in the and C horizons: in the A horizon under pasture the in this respect. Two of the coarser-textured members water contents of field-moist samples, and the laboratory involves wetting the soil to saturation, volumes of large pores in yellow-brown loams are of the group, formed on relatively recent sho~ers decrease in 15-bar water contents of samples which applying a pressure of 15 bar until equilibrium is significantly greater than those in only a few o~her from Mt Egmont and containing a little pumice, have been dried. These properties are thought to be reached then determining the gravimetric water soil groups and then in only the lower A honzon have subsoil available-water capacities from 18 to due to the presence of allophane which is commonly content.' For most non-allophanic soils the difference (Gradwell 1978-Tables 2 to 6 and Fig. 2). The 31 % of soil volume, values not equalled elsewhere in the dominant clay material in these soils. The unique in 15-bar water contents between field-moist and air yellow-brown loams are the only soil group for the data for yellow-brown loams (Gradwell 1976- which data are available that contain markedly more structure and extremely small size of allophane dried samples is small. With allophanic soils like the Table 2a). It seems that these two soils share some ?f particles 3.5-5.0 nm diameter), and the tendency of yellow-brown loams, however, the change in 15-bar pores (typically 20% by volume) larger than 60 µm the properties of the yellow-brown pumice soils, in in the upper and middle B than in the lower A these particles to form very stable aggregates on water content caused by air drying the soil is often moisture retention as well as in texture. drying, are the chief factors affecting 15-bar water large and mostly irreversible. retention in yellow-brown loams. 56 57 The water retained at 15 bar is probably both volume of micropore space and the specific surface SOIL CHEMISTRY adsorbed water on the particle surfaces and water area. It may also lead to the blocking off of many of held in pores whose entrances are less than 2 nm in the apertures which lead to the interior of the diameter. In the yellow-brown loams large amounts allophane spherules. SURVEY CHEMISTRY OF YELLOW-BROWN LOAMS of adsorbed water are to be expected because the Another factor which may account for the extremely small size of allophane particles results in decreased water retention of dried samples is the L.C. Blakemore and B.K. Daly Soil Bure~m D S 1 R L these soils having high specific surface areas. Many destruction of hydrogen-bonded clusters of water ' ' · · · ., ower Hutt micropores exist as void spaces within aggregates of molecules located in micropores within aggregates of allophane particles, and defect structures in the walls allophane particles. Wells & Furkert (1972) studied INTRODUCTION because it is dou~tful that these soils are true yellow of the hollow allophane spherules result in openings allophane using a technique of vacuum differential brown loams. It is more likely that the allopha . th ·1 · d . ne m which are only 0.3-0.7 nm in diameter. Conse thermal analysis which enabled the endothermic So~e results of analyses carried out at Soil Bureau ese so1 s is enved from podzolising processes quently the spherules remain water filled at 15 bar. peak associated with the loss of water to be resolved on sod survey samples of yellow-brown loams (Farmer 1979; Young et al. (1980). Each of these factors probably contributes to the into components that could be related to different collected within the last few years are reported in Analyses were mainly carried out according to high 15-bar water contents of field-moist samples of forms of bonding. They found that at natural Tabl_es 1 and. 2. The samples in the tables are methods described by Blakemore et al. (1977). yellow-brown loams. moisture contents, allophanes held most water in confmed to soils formed on volcanic ash and were Other methods used e.g. pH NaF KCl-Al h hydrogen-bonded clusters. However, allophanes selected to cover the main areas of the North Island ·d· , , exc ange In a recent study (Tuohy 1980) the effect on the ac1 ity, ~re adapted from the methods described in 15-bar water content of various drying pre which were dried to wilting point (15 bar) and then where yellow-brown loams occur. The so-called yellow-brown loams of Southland were not included U.S. Sod .survey Investigations Report No.l (Soil treatments was determined for six yellow-brown rewetted to natural moisture content, contained Conservatwn Service 1972). loam subsoils from the New Plymouth and mainly single water molecules which were hydrogen Inglewood regions. For each soil it was found that bonded to the clay surfaces. Air-dried samples were found to show an even greater inability to recover the drier the sample, the lower the 15-bar water Table 1 Sample information content of the rewetted sample (see Fig. 1). This the clusters of water molecules, and evidence that an decrease in water retention can be explained by the irreversible change in water retention had occurred was shown by the presence of surplus free water. Soil Lab. Depth Horizon Parent increased aggregation of the allophane particles on Location Management Soil Taxonomy* name no. (cm) material drying, which results in a decrease in both the a Field moist Ngakuru 9488 0-18 Alp Taupo Pumice Rotorua Cultivated - b Dried at RH = 9 0% sandy 18-25 AB MamakuAsh 70_ a N76/5/678023 Topdressed Entic Vitrudand -a loam 25-38 Bwl RotoruaAsh c Dried at RH = 70% 38-52 Bw2 WaiohouAsh 52-75 c Rotorua Ash -b Air-dried 75-95 uBwl 6Q - d (lapilli) a ,_,.... 95-115 uBw2 - Oven-dried at 4 115+ uBC ~ a e - -a cd '- Mairoa 9267 0-11 b A1 Late Quaternary Waitomo, S of Uncultivated - f oven-dried at 1 silt 11-24 Hydric Hapludand -50_ e BI airfall volcanic road junction of Topdressed - loam b 24--41 Bz1 ash Mairoa 6-. 41-57 Bz2 ( andesitic- b - 57-69 --cd Bz3 rhyolitic) - - a 69-84 JIB 4Q b -e f 40 -d Tirau 9432 0-18 A Late Quaternary - Matamata Co. Cultivated Entic Hapludand u c gritty 18-30 (B) airfall volcanic ...... ~ N66/273853 silt Topdressed ,_ -f - d 30-51 IIB ash c- b loam -e I-= 51-74 IIIB 30 d ..... 3 c- 74-100 me d c e - Horotiu 9434 0-18 A1 Rewashed volcanic Waikato Co. Cultivated - e silt 18-34 Entic Vitrudand e (B) material- N56/796525 Topdressed - loam 34--43 B3 possibly some 20_ f t.2 - 43-55 c addition of airfall ,__ f 55-72 c tephra on surface f 75-100 D, 10 10 Opua 9313 3-12 A1 Laharic breccia EgmontCo. Uncultivated loam 16-23 Typic Hapludand (B)A of Opua Formation N118/475506 Topdressed 24--44 (B) ( andesitic) 56-63 c 0 Kar aka T140 0-15 A Layered volcanic Manukau City Unc,uJtivated silt 15-29 Aquic Hapludand E F Bw ash (andesitic) N47/426367 Untopdressed loam 29-41 2Ab SOI l s PlES 62-77 2Bw 77-88 3Bw1 Figure 1 Gravimetric water contents at 15 bar of soil samples A-F, after the drying treatments indicated. 88-99 4Bll Locations and depths at which the soil samples were found are: 99-120 4B22 Soil sample Grid reference NZMSl Depth (m) Kopua 171 0-20 A Andesitic ash Southern Hawke's Uncultivated silt 20-35 Typic Vitrudand A Nl08/612888 0.3--0.6 Bw deposited as Bay Topdressed loam 35-50 B N108/621888 2.0 c alluvium N145/519541 C Nl09/670904 disturbed site 50-65 c D Nl09/681907 0.3--0.6 E Nl09/717956 0.3--0.6 *1978 proposal to subgroup level F N109/785803 disturbed site 58 59 Table 2 Analytical data Cation exchange (NH 0Ac pH 7) KCI ertr. Exch. ac. Tamm extr. P-ret. Kc Mg,. · P extr. pH Organic matter Phosphorus (mg%) 4 Soil Lab. Depth CEC I bases %BS Ca Mg K Na Al pH8.2 Al Fe Si s %C %N Truog ffiS0 Inm:g. Org. Total name no. (cm) ffiO NaF 4 (roe.%) (me.%) (me.%) (me.%) (me.%) (me.%) (me.%) (%) (%) (%) (%) (me.%) (me.%) (ppm) 4.7 9.4 6.8 0.52 7 105 115 72 187 Ngakuru 9488 0-18 19.7 4.5 23 3.9 0.13 0.36 0.12 1.2 41.2 1.67 0.52 0.54 74 0.08 0.9 74 0.25 38 45 41 86 sandy 18-25 5.2 9.8 3.4 11.1 1.8 16 1.4 0.03 0.25 0.08 0.11 29.1 2.4 0.65 0.98 91 109 9.6 2.2 0.17 35 41 29 70 loam 25-38 5.6 8.8 1.1 13 0.9 0.01 0.13 0.04 0.00 24.6 2.9 0.65 1.39 95 0.08 0.4 223 9.4 1.1 0.10 33 36 20 56 38-52 5.9 6.1 1.4 23 1.3 0.02 0.03 0.05 0.00 • 19.5 2.7 0.50 1.32 93 308 0.4 0.8 0.03 28 29 11 40 52-75 5.9 5.0 1.2 24 1.2 0.00 0.02 0.01 0.00 16.1 2.6 0.40 1.52 90 322 0.7 0.02 15 18 10 28 75-95 5.9 9.5 7.8 2.1 27 2.0 0.04 0.03 0.03 0.00 22.8 3.6 0.73 2.4 96 347 0.5 0.02 9 13 9 22 95-115 5.8 9.2 6.6 2.2 33 2.1 0.08 0.03 0.04 0.00 20.0 3.3 0.76 2.4 94 285 9.1 0.5 0.01 8 11 9 20 115+ 5.8 8.4 2.2 26 2.1 0.07 0.03 0.04 0.00 20.8 3.3 0.75 2.4 95 258 16 1.04 1 82 103 98 201 Mairoa 9267 0-11 5.1 11.3 35.4 8.9 25 7.0 0.86 0.71 0.31 0.43 4.6 2.4 1.13 85 0.09 2.2 120 0.59 22 28 44 72 silt 11-24 5.1 11.6 10.8 44.2 2.2 5 1.8 0.15 0.10 0.13 0.53 7.0 2.9 2.0 91 0.12 1.3 260 0.33 18 20 35 55 loam 24-41 5.2 11.2 5.5 31.4 0.6 2 0.4 0.05 0.09 0.09 0.10 6.8 1.93 2.5 95 1360 0.21 12 15 32 47 41-57 6.0 11.0 3.5 22.0 1.5 7 1.1 0.10 0.10 0.23 0.00 6.7 1.54 2.4 92 1580 0.16 12 16 28 44 57-69 6.1 10.9 2.9 20.2 1.8 9 1.4 0.13 0.09 0.17 0.00 6.7 1.52 2.5 99 1650 0.16 16 20 33 53 69-84 5.9 10.8 2.8 23.l 1.5 6 1.1 0.13 0.11 0.18 0.03 6.9 1.87 2.5 99 1950 0.71 4 129 128 121 249 Tirau 9432 0-18 5.4 9.6 7.9 29.7 14.4 48 12.4 0.90 1.02 0.12 0.15 43.8 3.3 0.59 1.32 88 0.12 1.9 125 0.16 0.3 30 34 28 62 gritty 18-30 6.2 9.9 2.0 11.3 5.6 50 4.2 0.48 0.82 0.13 0.00 25.0 4.1 0.72 2.2 98 0.14 1.4 418 0.2 25 28 16 44 silt 30-51 6.3 9.8 1.0 0.09 10.5 5.2 50 4.1 0.61 0.27 0.19 0.00 23.4 4.0 0.69 2.6 98 374 0.04 0.2 13 16 7 23 loam 51-74 6.4 9.5 0.5 12.5 6.1 49 5.3 0.38 0.16 0.27 0.00 20.3 2.8 0.41 1.71 91 157 0.2 7 9 7 16 74-100 6.5 9.4 0.5 0.04 13.2 7.5 57 6.5 0.45 0.13 0.44 0.03 18.3 2.4 0.49 1.29 86 112 51 63 72 135 Horotiu 9434 0-18 4.7 10.2 8.2 0.67 0.8 25.1 3.8 15 2.9 0.29 0.44 0.16 1.07 51.0 3.4 0.96 1.15 98 0.18 1.3 124 15 20 29 49 silt 18-34 5.6 10.2 3.3 0.27 0.2 17.0 4.1 24 3.4 0.24 0.33 0.12 0.02 36.5 4.5 1.34 1.98 99 0.18 1.3 225 0.1 9 13 12 25 loam 34-43 6.4 10.1 1.5 0.11 12.7 6.0 47 5.1 0.33 0.25 0.27 0.02 25.8 3.2 1.09 1.60 98 205 0.3 5 10 7 17 43-55 6.8 9.6 0.6 0.04 10.1 6.5 64 4.9 0.79 0.32 0.45 0.02 13.6 1.21 0.60 0.62 81 80 0.2 4 7 6 13 55-72 7.1 8.7 0.3 0.02 6.9 5.1 74 3.7 0.69 0.36 0.37 0.02 5.6 0.21 0.27 0.11 36 1 16 23 6 29 75-100 6.6 7.9 0.1 0.01 0.6 2.7 1.8 67 1.2 0.22 0.17 0.18 0.00 3.3 0.09 0.13 0.03 16 0 29 40 102 142 Opua 9313 3-12 5.6 10.8 13.8 1.03 0.6 38.4 19.6 51 15.0 2.36 1.83 0.40 0.18 63 3.0 1.20 0.83 94 0.17 1.5 54 12 25 48 73 loam 16-23 6.2 11.l 7.6 0.49 30.7 11.2 37 8.4 1.63 1.01 0.20 0.04 65 6.0 1.70 2.2 99 33 17 27 48 75 24-44 6.7 11.2 5.5 0.37 23.l 8.8 38 6.1 1.64 0.84 0.20 0.01 56 6.6 1.31 2.6 99 0.09 2.6 54 55 78 21 99 56-63 6.5 1.4 0.06 7.7 2.5 33 1.3 0.52 0.55 0.17 0.02 3.1 0.92 1.53 99 92 Karaka T140 0-15 6.0 9.8 8.3 34.2 17.4 51 14.5 1.56 0.91 0.38 0.18 4.5 0.84 1.53 94 silt 15-29 6.1 9.9 3.7 22.2 10.9 49 9.2 0.75 0.77 0.21 0.04 5.3 0.86 2.10 99 loam 29-41 6.2 9.9 4.1 21.8 12.0 55 10.4 1.05 0.24 0.26 0.10 .5.2 0.93 1.96 99 41-62 6.4 9.7 2.2 18.3 10.6 58 9.1 1.25 0.04 0.20 0.10 5.2 1.00 2.3 99 62-77 6.5 9.6 1.6 18.5 10.4 56 8.6 1.53 0.04 0.22 0.08 4.8 0.62 2.3 99 77-88 6.4 9.4 1.3 18.3 9.5 52 6.7 2.41 0.04 0.31 0.10 5.6 0.42 2.4 98 88-99 6.2 9.4 2.1 26.8 7.5 28 4.6 2.63 0.04 0.23 0.05 6.4 0.17 2.9 100 99-120 5.8 8.9 3.1 41.2 5.0 12 2.6 2.30 0.03 0.05 0.08 8.2 0.06 3.1 99 Kopua T71 0-20 5.5 9.6 9.3 27.9 13.1 47 11.9 0.69 0.43 0.10 0.34 49.1 2.2 0.99 0.50 89 stony 20-35 6.0 9.8 4.6 17.5 6.4 57 5.9 0.28 0.08 0.13 0.14 39.8 2.9 1.21 0.84 97 silt 35-50 6.0 10.3 3.4 14.0 4.9 35 4.4 0.24 0.09 0.17 0.13 37.1 3.1 1.36 1.04 97 loam 50-65 6.2 10.0 2.6 11.3 4.5 40 4.0 0.23 0.08 0.15 0.09 29.6 2.6 1.13 0.84 96 tables all have pH NaF greater than 9.4 except ORGANIC MATTER 2. Generally, yellow-brown loams have very high where alluvial (or other) layers are encountered. proportions of their inorganic phosphorus soluble in 0.5M HzS0 • This is indicative of weak Results in Table 2 show the topsoils to be more This level (pH NaF 9.4) is used as the lower level for Percent carbon values are medium to high in the 4 domination of an exchange complex by amorphous topsoils (Table 2) and it is characteristic of yellow weathering status and low degree of occlusion of acid than the subsoils due to effects of organic phosphorus into fixed forms. These are in sharp matter. The subsoils are only slightly acid to near material in Soil Taxonomy (Soil Survey Staff 1975). brown loams that %C remains relatively high throughout the profiles due to formation of stable contrast in soils such as are found in Tonga, which neutral because of the lack of permanent charge sites An interesting feature of the Karaka soil is the mineral-organic complexes. This stability is also are also formed on volcanic ash but are weathered where hydronium or aluminium ions can be held. relatively low pH NaF (8.9) of the lowest horizon, ~eflected by the high carbon to nitrogen ratios which to brown granular loams and in which only about Because pH-dependent charge is dominant in these which has obvious properties associated with Indicate resistance to biological breakdown of 25% of the organic phosphorus is soluble in 0.5M soils, pH does not correlate with base saturation (by presence of large amounts of allophane (high P organic matter. H S0 . ammonium acetate) and most variability in pH is retention, high Tamm Al and Si). On air drying, the 2 4 3. The proportions of total phosphorus which are due to the effects of organic acids. soil formed very hard aggregates and it is apparent in the organic form are comparatively high. This that this aggregation, by reduction of effective PHOSPHORUS reflects the high organic status of these soils surface area, has caused a relatively low pH reading. which, in tum, is an effect of the formation of NaF By replacing the normal 1 minute initial stirring by 1 1. Easily available phosphorus (as represented by stable organic complexes with amorphous con minute ultrasonic treatment, a pH NaF of 10.5 was pH values obtained in 1 M NaF after 2 minutes Truog values) is normally low in yellow-brown stituents. obtained. When field-moist soil was used with the loams. The results for the topsails of the Ngakuru stirring are high in yellow-brown loams because they 4. Phosphate retention (P retention) is an empiri normal stirring procedure, a pH NaF of 9.7 w~s and Tirau soils probably reflect the effects of have large areas of active surfaces which can cal measure of the ability of the soil to remove obtained, (ultrasonic treatment of non-allophantc topdressing. exchange OH- ions for F- ions. The soils in the soils did not increase the pH NaF markedly). phosphorus rapidly from solution, a process 61 60 MAGNESIUM CATION EXCHANGE PROPERTIES OF YELLOW-BROWN LOAMS which i.s considered to be a precursor to the much slower process of phosphorus fixation which Exchangeable values range from very low to D.C. Edme&des, Ruaku.ra Agricultural Research Centre, Hamilton renders phosphorus unavailable to plants. Phos medium. The very low values are found in the phate retention values are very high in yellow Ngakuru soil and the subsoil of Mairoa and are low brown loams. The results have been placed near enough to suggest possible magnesium deficiency in CATION EXCHANGE CAPACITY accumulates. In this regard the work of Perrott the Tamm values in Table 2 because it has been the Ngakuru soil. Reserve magnesium (Mg,) values (1978a) is of interest for he showed that organic shown (Saunders 1965) that there is a dose are all very low in the profiles reported. A distinguishing feature of the yellow-brown matter, when added to alumino-silicates and soil relationship between P retention and Tamm Al loams is that, in comparison with other New Zealand days, had an effect on the negative charge over and for most soils. Because the P retention method is soils, they possess considerable variable negative above the addition of extra functional groups. He POTASSIUM designed to differentiate the whole range of New charge (Fieldes & Schofield 1960, Blakemore & suggested that this may be due to the removal of Zealand soils, yellow-brown loams tend to be Parfitt 1979, Edmeades 1981). It is not within the charge-balancing species, such as Al hydroxides, EJi!changeable values in all samples are highest in crowded into the top end of the scale. Therefore, scope of this article to discuss the origin of this during the formation of these organo-mineral topsoils and generally are lower in subsoils. Overall, the correlation within the yellow-brown loam variable charge (see Fieldes & Schofield 1960, complexes. topsoil values range from low to high. Reserve group between P retention and Tamm Al Blakemore & Parfitt 1979, Theng 1979) except to potassium (KJ status in these soils is very low due to weakens. say that it arises from organic ( carboxyl and lack of layer-silicate minerals, and for this reason phenolic) and inorganic (Fe and Al oxides and CATION SELECTIVITY Generally, A horizon P retention values are exchangeable potassium values in these soils are a hydroxides) soil components. The net negative lower than the rest of the profile. This good indicator of potassium status. demonstrates the effect of organic matter charge on such surfaces depends largely on the Cation selectivity, or the preference of one cation decreasing the ability of amorphous constituents activity of H + and OH - in solution. Consequently, over another determines in part the relative proportions of cations on the exchange complex. For to retain phosphate. EXCHANGE ACIDITY the CEC of these soils which is, of course, a measure of the net negative charge, depends on the pH at most soils the order of preference is Ca> Mg> K> Na which is a result of both valency and ionic radii Exchange acidity is the acidity measured by which the measurement is made. effects (Helfferich 1962). In this quantitative sense CATION EXCHANGE releasing exchangeable aluminium and hdyrogen The relationship between pH and CEC for several the yellow-brown loams are similar to other soils, as with an exchanging cation at pH 8.2. In yellow yellow-brown loams is shown (Fig. 1), and for these is <;Iemonstrated by the Gapon-type selectivity In yellow-brown loams, cation exchange (CEC) as brown loams where there are high amounts of three examples changes in CEC of 12 to coefficients in Table 2 for the Ca-Mg and Ca-K reported (i.e. ammonium acetate, pH 7 and washing variable charge, the exchange acidity values are very 16 me.(100 g)-1 per unit change in pH were found. with alcohol) is in disrepute for several reasons. high. This is particularly so in topsoils where organic Such changes are much larger than found for other Table 1 Exchangeable cations, effective CEC and These include the fact that such soils have high matter makes a considerable contribution to variable New Zealand topsoils (Blakemore & Parfitt 1979, CEC measured with lM NH 0AC for some variable (pH-dependent) charge properties due to 4 charge. Edmeades 1981), reflecting the relatively high selected yellow-brown loams the presence of amorphous materials and high contents of organic matter (Blakemore & Miller contents of organic matter. Therefore, CEC values Exchange acidity values can be used to estimate 1968) and allophane (Fieldes 1968). determined at pH 7 are much higher than would CEC at pH 8.2 by adding it to Ibases. Soil Exchangeable cations (me.(100 g)-I) pertain at natural pH. Other reasons include errors Altering the ionic strength of the soil solution also mime pH Ca Mg K Na Al ECECtEC* caused by the effects of salt adsorption during alters the CEC of soils with variable negative charge, TAMM OXALATE EXTRACTABLE Al, Fe AND Si analysis and difficulties which arise through the use thr~:mgh its effects on hydrolysis and salt absorption. New Plymouth 5.6 14.8 3.23 1.69 0.39 0.24 20.7 51.8 of alcohol to remove the excess ammonium acetate. ThlS has been shown to be of importance in soils and Patua 5.3 5.3 1.43 0.69 0.34 0.61 8.6 47.8 Tamm values obtained by extraction with acid Inglewood 5.2 6.7 1.13 0.66 0.33 0.50 Thus CEC (ammonium acetate) is of dubious value clay~ containing allophane (Wada & Harada 1969). 9.6 41.7 Mairoa 5.5 7.9 1.29 0.80 0.29 in determining such properties as lime requirement oxalate solution represent amorphous and organi Dunng (1973b) has demonstrated similar effects on 1.10 10.3 64.1 cally complexed constituents. For this reason such Te Kuiti 5.7 12.1 1.81 0.61 0.26 0.38 14.8 65.6 and leaching status. some New Zealand soils rich in allophane. Ohaupo 5.6 13.4 1.32 1.37 0.31 0.21 16.6 N.D. values are very high, especially for Al and Si in Waihou 5.8 12.5 1.52 1.67 0.18 0.17 16.0 N.D. Sum of cations (Ibases and KCl extractable Al) yellow-brown loams. The amounts and proportions Additional problems in defining CEC arise from can be used to approximate CEC at natural pH and of Al, Fe and Si so extracted are used in analytical procedures. It has been shown that the :j:effective CEC as sum of exchangeable cations therefore the % base saturation at natural pH can be mineralogical studies of these soils. CEC of soils, particularly those containing allophane *CEC determined using neutral lM ammonium acetate derived. However, for yellow-brown loams where ?nd oxides of Fe and Al, depends not only on the extractable aluminiums are very low (Table 2), % index cation (Wada & Harada 1969) and anion (Juo Table 2 Selectivity coefficients* for the calcium- • Ca base saturations derived by this method will always PHOSPHATE EXTRACTABLE SULPHUR et _al. 1976) used but also the washing procedure ~agnesmm exchaneae (Ks M~ and calcium-potass- be near 100 and these too are of little value for (Birrell & Fieldes 1968). During (1973b) has shown mm exchange (K8 K) for some selected yellow determining leaching status. Study of cation The values in Table 2 are all extremely high except that these effects can account for large errors in CEC brown loams (from During 1973a) exchange data (Table 2) suggests that the most for non-amorphous layers in the Horotiu soil. The on a Dunmore soil. very high values obtained suggest that sulphur useful value in this respect is Ibases. For example, Soil K Ca* Kea• the Mairoa and Ngakuru soil samples show quite deficiency is unlikely and they reflect the high anion For the above reasons it has become useful to SMg SK dearly the effects of strong leaching conditions in exchange properties of such soils. define the term effective CEC (ECEC) as the CEC at field pH and ionic strength. This can be taken as Egmont 2.4 15.2 the very low Ibase figures reported. the sum of the exchangeable cations present at field Stratford 2.5 15.6 conditions, and includes not only the exchangeable Ohaupo 2.1 3.8 SUMMARY Waihou 2.5 13.1 CALCIUM bases, Ca, Mg, K and Na, but also Al, Mn and H + if The chemical properties of yellow-brown loams these are present. However, the amounts of Al and *calculated as the Gapon coefficients Exchangeable values probably reflect the degree are dominated by the presence of large surface area, ~f+ (and Mn) are generally low (<1 me.(100 g)-1) K Ca_ (Ca) LM.e:] of leaching with the stronger leached members active, amorphous constituents. The effects of these ~n most yellow-brown loam topsoils, especially if pH SMg -(Mg) . [Caj and is >5.0, (Birrell & Fieldes 1974 and Table 1). As a (Ngakuru and Mairoa) having low values throughout are reflected in the very high Tamm Al and Si K Ca=~ [KJ the profile. Values are highest in topsoils due to contents and very high P retention values, the high result, the sum of the exchangeable bases can be SK (K) . V[Q.j organic matter and possibly effects of topdressing amount of variable charge (high exchange acidity), Used as a practical guide to the ECEC of these soils. ~here the parentheses indicate amounts of exchangeable cations 1 (range 3-15 me.%). Overall, except Al horizons, high pH NaF, high phosphate extractable sulphur Since organic matter contributes to CEC it is m me.(100 g)- and the square brackets indicate solution values range from medium to low. and the relatively high amounts of organic matter concentrations in mM. No correction has been made for ion e.<:pected that CEC will increase as organic matter activities. throughout the profile. 62 63 30 Secondly, because of the large amount of variable may not result in better retention of cations other negative charge in these soils their ECEC can be than Ca on these soils, because of the dominant role significantly increased by changes in soil pH which of Ca. are attainable at practical rates of liming. Such Thirdly, the strong preference which these soils increase in ECEC per se should result in better exhibit for Ca relative to the other cations, coupled retention of cations against leaching and hence with the continual addition of Ca in limestone and New Plymouth improve their utilisation; this is particularly relevant superphosphate, means that Mg and K will be to the mobile cations K and Mg and to the yellow readily and continually displaced from the exchange brown loams, given their free draining properties. complex, and greater losses through leaching may However, as has been discussed elsewhere result. (Edmeades 1981), increasing the ECEC by liming 20 SORPTION OF PHOSPHATE SELECTED YELLOW-BROWN LOAMS R. W. Tillman and J. K. Syers Department of Soil Science, Massey University, Palmerston North The generally high phosphate (P) fertiliser (Rennes 1978) and the Dannevirke silt loam (Hope 10 requirements of yellow-brown loams (During 1972) 1977). The effects of cations, certain inorganic and have stimulated considerable interest in the organic anions, and ionic strength on P sorption, immobilisation of P by these soils. In the along with kinetics, have been studied. The studies development phase, substantial amounts of added P show that these soils have a very high capacity to can be immobilised in organic forms (Jackman sorb P from solution and that an initial rapid 1964). Also, the very high P retention values are removal is followed by a slow reaction. indicative of a potentially large inorganic P sink in yellow-brown loams. There is little doubt that the high P sorption capacity of yellow-brown loams can be attributed to Although there is still some controversy as to the allophane content of the soils, although this may whether sorption or precipitation reactions are be enhanced by the presence of iron (Fe), as hydrous involved in P retention, it is generally agreed that ferric oxide (ferrihydrite) (Ryden & Syers 1975) the chemistry of inorganic P in soils can best be and/or in the allophane structure as a substitution for described using a sorption model. For the purpose of aluminium (Al) (Parfitt & Henmi 1980). oL-~~~--~.~~~~_,...1..__~~~~5~.5:--~~~-1..~~~~-6~·~0--~~-- 5 2 this paper it is assumed that a sorption mechanism operates during the determination of P retention, as There has been a great deal of research carried out Soil reported by Saunders (1965) and N.Z. Soil Bureau in New Zealand and elsewhere aimed at elucidating the mechanisms by which P is sorbed by soils and soil (1968). Figure 1 The relationship between soil pH and CEC for three yellow-brown loams components. Although it is well recognised (Saun Saunders (1965) quotes P retention values of ders 1965, Syers et al. 1971) that P is strongly sorbed 93±1%for11 yellow-brown loam topsails developed exchange reactions. Generally, increasing the soil the Al/Si ratio. Conversely at high Al:Si ratios and by compounds of both Fe and Al in soils, more pH or organic matter content increases the surface alkaline pH, Mg was specifically absorb~d, and the from andesitic and rhyolitic ash. Values in excess of detailed evidence is available on the mechanisms of 90% are always obtained for yellow-brown loam P sorption by the crystalline and short-range order charge density, and hence increases the preference addition of organic matter decreased this. for the preferred ion (Perrott 1978a and unpub topsails (L.C. Blakemore, pers. comm.) and these oxides and hydrous oxides of Fe than is the case for lished, Edmeades & Judd 1980) thereby exaggerat may reach 99% for lower horizons of Tirau silt loam. Al. In particular, the sorption of P by naturally Retention values invariably increase with depth in occurring allophanes extracted from soils has been ing the above order. PRACTICAL IMPLICATIONS yellow-brown loam profiles. This is well shown by investigated in only a very few studies. In New During (1973a) found that some yellow-brown the data for several profiles reported in 'Soils of New Zealand, Rajan (1975b, 1975c), Perrott (1978b) and loams were exceptional in terms of their selectivity Several important consequences result from these Zealand' (N.Z. Soil Bureau 1968). The lower P Parfitt and Henmi (1980) are among the few who for K (the Ohaupo soil in Table 2 is an example), properties. sorption in topsails may be partly attributable to the have specifically studied the adsorption of P by and other results (Edmeades 1980) suggested that higher organic matter content, although the work of allophane, although Ryden and co-workers have the yellow-brown loams may have a greater Firstly, in regard to the measurement of CEC, t~e Perrott (1978b) indicates that organic treatment of worked extensively on the allophane-rich BC preference for Ca than other New Zealand soils. considerable variable negative charge of these soils synthetic amorphous aluminosilicates and allophanic horizon of the Egmont black loam (e.g. Ryden et al. Possible explanations for these results may be means that .both pH and ionic strength must be soil clays does not always decrease P sorption. 1977a). inferred from the detailed studies by Perrott carefully reproduced to obtain a measure of CEC at Many workers have, however, studied the (unpublished). He showed that aluminosilicates and field conditions. More specifically the traditional The sorption of P by samples from several yellow neutral lM NH 0AC method will overestimate brown loams has been studied in detail. These sorption of phosphate by other Al-containing clay minerals rich in amorphous materials had a 4 compounds such as gibbsite (Kyle et al. 1975, Parfitt greater selectivity preference for K than expected on CEC, the extent depending on how much the field include the Egmont black loam (Ryden & Syers et al. 1977), hydrous alumina (Rajan et al. 1974, theoretical grounds, suggesting a specific interac pH and ionic strength differ from the conditions 1977; Ryden et al. 1977a, 1977b, 1977c, Earl etal. Rajan 1975a) and synthetic aluminosilicates or tion. The extent of this interaction was dependent on imposed by this method (Table 1). 1979, Russell et al. 1981), the Egmont brown loam 65 64 MAGNESIUM STATUS OF YELLOW-BROWN LOAMS 'synthetic allophanes' (Cloos et al. 1968, Rajan & It is commonly assumed that P bound to Al is held Perrott 1975, McLaughlin et al. 1981), and the similarly, but there is very little direct evidence. results of this work have been applied to allophane. Working with kaolinite, Kafkafi et al. (1967) M. A. Turner Tue validity of this approach can be questioned. suggested that because two Al-OH groups were Department of Soil Science, Massey University, Palmerston North Parfitt and Henmi (1980) have argued that although 0.296 nm apart some P could be bound through a and gibbsite sorbs very much less P than allophane 'it is bidentate complex. Kyle et al. (1975) noted this R. Lee, Soil Bureau, D.S.I.R., Lower Hutt appropriate to use gibbsite as ~ model_ for phosphate work and suggested that such a bridging structure sorption on allophane and 1mogohte because a was consistent with the limited exchangeability of P INTRODUCTION The critical level for pasture, at which absolute gibbsite-like sheet is present in i~ogolite ~tru~t~res'. sorbed on gibbsite at certain pH values. deficiency is expected, is generally considered to be The extent to which synthetic alummos1hcates Recent work by Henmi and Wada (1976), Wada There are at least three major sets of factors within the range 0.2-0.3 me. Mg/100 g soil. For resemble naturally-occurring allophane is less clear. (1977), and Wada and Wada (1977) has sug~ested governing the supply of soil Mg to plants: crops, a higher critical value of around 0.5 me. Rodrique and Declerk (1975) and Pyman et al. that allophane is composed of hollow, sphencally (a) soil chemical factors (including soluble and Mg/100 g is often suggested. Another common (1979) have demonstrated th~ existence of _a shaped particles, and Parfitt and Henmi (1980) ~a~e exchangeable Mg contents, pH, CEC) method of expressing Mg content is as a relative heterogeneity in composition m synthetic saturation of total CEC, with ideal Mg saturations ~any proposed that P is sorbed at ?efe~ts '?r pores w1t_hm (b) soil physical factors (texture, temperature, aluminosilicates which is not present m at least some often put at around 10% (Metson 1974). the spherical wall, where g1bbs1te-l~ke e?ge s1~es water content), and naturally-occurring allophanes (Pyman et al. 1979). exist. By making a number of assumptions, mcludmg Farmer et al. (1977) and Wada et al. (1979) have the suggestion that P bridges between two Al atoms, (c) plant factors (species, stage of growth, nutrient Reserve Mg (Mgr) interactions). demonstrated that structures similar to naturally these workers have calculated that there are Various chemical methods have been used to occurring allophane and imogolite can be formed_ in approximately six such defects per spherical unit of Whilst, undoubtedly, all three play their role(s) in provide a measure of the non-exchangeable synthetic aluminosilicates, but the extent to which allophane. yellow-brown loams, this article is concerned only magnesium that may become available to plants this occurs is greatly dependent o~ the m~thod An increase in the sorption of P with increase in with soil Mg contents (especially forms) since these through weathering. One method, developed by preparation. Estimates as to the relative capacity t? ultimately determine both the short- and long-term Metson and Brooks (1975), was designed to extract sorb p of allophane compared to other so_il Al content has been observed by Cloos et al. (1968) supplying power of any soil. an 'accessible' fraction of mineral Mg through acid components based on comparisons of synthetic for synthetic aluminosilicates, and by Rajan (197~b) dissolution of secondary clay minerals and surface compounds,' should therefore be treated with and Parfitt and Henmi (1980) for naturally-occurrmg This review draws mainly on the work of Alan attack on primary minerals. The method involves a caution. allophane clays. No definite explanation for these Metson and co-workers, at Soil Bureau, together phenomena, in terms of the more recently proposed with recent data obtained at Massey University for single fifteen-minute extraction with 1 M HCl, at a Tue extensive literature on the mechanisms by structures of allophane, has been advanced, but the Taranaki yellow-brown loams. 1 :40 soil to extractant ratio. Exchangeable Mg is which P is sorbed by soils and soil components has fact that net negative surface charge, at a given pH, subtracted to give the estimate of M~. been well reviewed by Parfitt (1978). The reactive decreases with increasing Al content (Wada & No 'critical' value for Mg,. has been suggested. sites for phosphate sorption in pure systems,_ and Okamuru 1977) would assist the sorption of P. In FORMS OF SOIL MAGNESIUM However, low values are taken to indicate the probably also in natural are the smgly alloph~nes, addition, the surplus silica in allophanes of low. Al possibility of Mg deficiency if and when Mge supplies co-ordinated Al.OH groups which are exposed at content may act to block some of the adsorpt10n Total soil Mg can be subdivided into the following are exhausted. surfaces. At lower pH values, these sites may adsorb sites. categories (or pools): protons to form Al. OHi+ groupings .. Sorption of Pat The mere demonstration of an appreciable (a) soluble Mg (Mg )-dissolved in the soil low concentration occurs by a hgand exchange In summary, the large capacity of yellow-brown 5 content of Mg,. is no guarantee of freedom from Mg loams to sorb P is one of their most important solution process in which the OH - or OH2 group is repl~ced deficiency, because the rate of release of this Mg is by a Al-0-P bond. This process c;>f sorptlo~, chemical characteristics. This high P sorption (b) exchangeable Mg (Mge)-adsorbed, non-speci markedly dependent on prevailing environmental involving the formation of distinct chermcal bonds, is capacity can be attributed to the allophane content fically, at cation exchange conditions. In a strongly weathering environment, a also known as chemisorption. Rajan (1975b, 1975c) of these soils, although other short-range _order sites on both organic and given quantity of Mg,. is more effective than would has demonstrated that the sorption of P on soil compounds of Fe and Al may also contnbute. inorganic soil colloids, and be the case in a weaker weathering situation. For allophanes at low concentrations occurs by ligand Although much work has been done on. the (c) non-exchangeable Mg, comprising: this reason, alone, the absolute size of the reserve exchange with the displacement of som~ sorbed mechanism by which P is sorbed by synthetic ~l (1) acid-soluble Mg (Reserve Mg, Mgr); poten pool of Mg can be a misleading index of potential sulphate and silicate in addition to OH - 10ns and compounds, further work is required on actual s01l tially-available but non-exchangeable Mg con supply. H 0. allophanes. Particular emphasis needs to b~ placed tained within primary and secondary minerals 2 on the sorption behaviour of allophane soil~ after (2) residual Mg; generally estimated as the At much higher concentrations of P there appears regular additions of superphosphate, and m th_e difference between total Mg and the sum of . SUGGESTED CRITERIA FOR SOIL to be considerable disruption of the surface and the presence of a large build-up of o~ganic matter: '_fh1s MAGNESIUM LEVELS Mg and M~. release of structural silicon (Rajan 1975c). Such high information is required to make mformed dec1s10ns 0 concentrations are unlikely to occur in the soil on suitable maintenance fertiliser requirements for Exchangeable (plus soluble) Mg is universally The following guidelines are used to interpret the solution, except perhaps in the vicinity of a fertiliser these soils. regarded as the fraction immediately available to Mg status of New Zealand soils (Metson & Gibson granule. plants. Acid-soluble Mg slowly replenishes this 1976): Considerable evidence has accumulated (Parfitt available pool. Residual mineral Mg probably 1978) to suggest that P sorbed by both crys~alline Adrnowledgments contributes little in the way of potentially-available The authors wish to thank Dr J.H. Kirkman for Mg, at least in the short term. Form (in me./100 g soil) and short-range order oxides and hydrous oxides of Mg. Total Mg Fe is held by a bridging arrangement: helpful discussion on the structure of allophane. /FeO"'- /0 METHODS FOR DETER.MINING AVAILABLE very high >7 >30 >150 0 p AND RESERVE MAGNESIUM high 3-7 15-30 70-150 'FeO/ 'oH medium 1-3 7-15 30-70 low 0.5-1 3-7 15-30 very low <0.5 <3 <15 Available Mg (Mg,+ Mg.,) Available Mg is generally determined by leaching *These ratings should not be interpreted to imply adequacy or Soil samples with 1 M ammonium acetate at pH 7. deficiency for plants; such a relationship has not yet been demonstrated 67 66 In addition to a major effect of parent material Mg expressed, from scientific and non-scientific quar ters, about the precarious Mg balance operating in The soils of this group are particularly concen content on soil Mg content, the amounts of the PATTERNS OF DISTRIBUTION OF many New Zealand soils, including the rhyolitic trated in the Taranaki district. Values for two various forms of Mg present are also affected by MAGNESIUM IN YELLOW-BROWN LOAMS other factors such as: members of the yellow-brown loam group. On yellow-brown loams of this grouping are: today's evidence (as discussed previously) this Mg. Mgr Total Mg (a) leaching intensity-which increases with The four groupings of yellow-brown loams used (in me./100 g soil) increasing rainfall at higher altitudes concern may well encompass the coarser textured by Metson and Gibson (1976) are retained in this andesitic members of the group. Egmont black loam (weakly leached) 5.4 4.9 100 (b) weathering intensity-which decreases with article. It is, however, recognised that other 3.9 107 Patua loam (strongly leached) 2.0 increasing coarseness of the tephras (closer to Along with the continual removal of Mg in the classifications will be possible, especially as new form of animal and plant products and the criteria for recognising and describing these soils are source) and cooler temperatures operating at u<>lll"'"'-11-"'.,"'"'"" loams from mixed andesitic higher altitudes, and unquantified loss occurring by leaching, there are developed. The groups are: strong reasons for believing that Mg deficiency will rlf.,mnliifi'i.r> tephras (or ashe!i) (c) fertiliser practices-which often modify and increase on certain Taranaki yellow-brown loams in 1. Southern obscure inherited patterns of soil Mg content. 2. Central (from andesitic tephras) These soils are common in the King Country and the future, unless corrective measures are taken. Potassium fertilisers can lead to a decrease in Mge 3. Central (from mixed tephras) Waikato districts. Their Mg status is probably a fair The situation is exacerbated by the all-too-common contents, whereas Mg fertilisers can increase 4. Central (from rhyolitic ashes) indication of the relative proportions of the original practice of adding large amounts of potassium them. andesitic and rhyolitic component tephras. fertilisers to these soils. In addition to accelerating In general, yellow-brown loams derived from Soil Mge contents as low as 0.14 me./100 g have leaching losses of Mg, excessive K can depress the relatively young, fine-textured andesitic ashes e.g. Mg. Mg, Total Mg (in me./100 g soil) been found in Taranaki, especially around the plant availability of the remaining soil Mg. One contain: Mairoa silt loam 0.73 2.3 32.2 Inglewood and Stratford areas. There are probably means of redressing this imbalance would be to very low to medium amounts of Mge other pockets of soils where similar low contents can utilise Mg compounds in the annual fertiliser very low to low amounts of Mg,. and be found. Such low Mge contents, combined with applications. high amounts of total Mg low Mg,. supplies and slow rates of transformation of The high contents of total Mg are due to the the reserves, indicate a real possibility for the Central yellow-brown loams from rhyolitic ashes FERTILISER ADDITIONS IN RELATION TO abundance of ferromagnesian minerals and inter existence of Mg deficiency on a number of soils in SOIL MAGNESIUM CONTENTS mediate volcanic glass in the sand fractions (Metson Taranaki. & Brooks 1975). However, in spite of high total Mg, These members are especially prominent in the The key point is the coarseness of the tephra, yellow-brown loams characteristically possess low Waikato district and appear, in many respects, to be It is sometimes helpful to express the size of soil which imparts chemical and physical properties that nutrient pools in terms of fertiliser equivalents. In contents of reserve Mg. This situation is believed to more closely related, chemically, to typical yellow resemble yellow-brown pumice soils more than the the case of Mg this may throw some light on the be due to the low Mg contents of the dominant clay brown pumice soils than to yellow-brown loams. typical andesitic yellow-brown loams. feasibility of materially influencing the available minerals (allophane, hydrous feldspars, amorphous Thus they have some properties in common with supplies in the soil, at least in the long term. oxides, and sometimes halloysite) such that upon soils that are amongst the most Mg deficient in New If these susceptible soils are not actually Mg Officially, of course, at the time of writing, Mg is not acidic dissolution of these secondary minerals only deficient at the present time, then they may become Zealand. yet recognised as a 'fertiliser' ingredient but rather small quantities of Mg are released. so in the future as depletion continues and land use These yellow-brown loams possess characteristi intensifies. as a lowly 'additive'. As a rule, the Waikato yellow-brown loams, cally low to medium contents of Mge, very low .Mgr For a typical yellow-brown loam containing 1, 4 derived from rhyolitic ash and pumice, tend to be and low to very low total Mg. One example IS: lower in both Mge and Mg,. than their Taranaki and 100 me./100 g of Mge, Mg,. and total Mg, Mg. Mg,. Total Mg RELATIONSHIPS BETWEEN FORMS OF respectively, and with a bulk density of0.6 Mg m-3, (m me./100 g soil) counterparts. MAGNESIUM the actual amounts of the various forms of Mg Horotiu sandy loam 0.35 1.6 18 lodged within an area of 1 ha, to a depth of 7.5 cm, Southern yellow-brown loams Of all the groups, this one is expected to be the A summary of inter-relationships between the would be: most susceptible to Mg deficiency. In fact, Metson various forms of soil Mg and selected soil properties Although not of volcanic origin, in the past these 54 kg Mge soils have been included within the yellow-brown and Brooks (1975) consider them as either 'actually has been published by Metson et al. (1977). The main findings are summarised below, subdivided on 216 kg Mg,. loam group because of certain affinities with North or potentially Mg deficient'. and 5400 kg total Mg Island yellow-brown loams, e.g. similar chemical the basis of the four yellow-brown loam groupings of and physical properties and soil profile mor Metson and Gibson (1976): For such a soil the amount of readily available Mg phologies. They are coarse-textured soils formed on MAGNESIUM STATUS OF TARANAKI (Mge) is equivalent to approximately 500 kg old morainic deposits or outwash gravels in Western YELLOW-BROWN LOAMS Regression Southem Central Central Central dolomite (assuming all the Mg to be plant available) Otago. They possess very low Mge contents YBL YBL(a) YBL(r-a) YBL(r) or serpentine (assuming 50% availability of its Mg) (indicative of a strong leaching environment) and The Taranaki yellow-brown loams exhibit a wide per ha. range of Mg and Mg,. contents, even though they are vs org. C medium contents of Mg,. and total Mg (as the result 3 Mg0 0.645 n.s. -0.091 n.s. 0.998* 0.376 n.s. usually well-supplied with total Mg. This range of If, however, the situation was 0.2, 2 and of a weak weathering regime). ~g,, vs CEC 0.523 n.s. 0.147 n.s. 0.909* 0.290 n.s. available and potentially available soil Mg contents g, vs Mg. -0.431 n.s. 0.127 n.s. 0.394 n.s. 0.023 n.s. 20 me./100 g of Mge, Mg,. and total Mg, then the l'otal Mg vs Mg, 0.989*** -0.097 n.s. -0.848*** 0.739*** e.g. Mg. Mg,. Total Mg is sufficiently great to encompass situations that amounts of Mg present in a 1-ha 7.5-cm volume (m me./100 g soil) would probably be unable to deliver Mg at a rate fast would be: Te Anau sandy loam 0.7 7.6 45.6 enough to match plant and/or animal demands Briefly, these results show no real evidence for 11 kg Mge during critical periods. P.W. Shannon (pers. comm.) any useful overall correlations between the variables 108 kg Mg,. Central yellow-brown loams from andesitk tephras instanced several young soils ( <5000 years B. P.) on e~amined. In particular, Mgr was not related to and 1080 kg total Mg coarse textured andesitic tephras that contained either Mge or total Mg, so that independent methods Soils within this group typically have high total Mg lower Mge contents than much older soils on finer I~ this case the amount of readily available Mg is for the direct measurement of reserves are indicated. eqmvalent to only 100 kg of dolomite or serpentine. but low Mg,. contents. Exchangeable Mg contents textured tephras. For example, Inglewood coa~se vary with soil texture and intensity of leaching sandy loam, on Inglewood Tephra, often contains With estimates of product removals and leaching of the order of 10-20 kg Mg ha-1 y-1 the Mg contents (Turner et al. 1978). less than 1 me ./100 g of Mge. This value is closer t? SOIL MAGNESIUM BALANCE that found for soils of the yellow-brown pumice soil of this latter soil would be soon depleted unless There is evidence that the original Mg contents of considerable mineral weathering occurs to replenish group than for the more typical Taranaki yellow· For many years now there has been concern the tephras within which these soils are developed available supplies. vary, with consequent effects on initial soil Mg brown loams, such as the finer textured Egmont and contents (V.E. Neall, pers. comm.). New Plymouth loams. 68 69 In view of the drain on soil Mg supplies that susceptible Taranaki yellow-brown loams if Mg shows that these particular properties are relevant to isotopically labelled sulphate (0.05 mCi 35S per litre) undoubtedly accompanies most common land use fertilisers are not employed. The frailty of some of sulphate adsorption characteristics of soils from the to enable measurement of the sulphate in the options, there is obvious reason for concern that Mg the central yellow-brown loams can be judged from West Indies (Haque & Walmsley 1974), from leachate by scintillation counting. deficiency will increase in the future on a number of the above examples. Australia (Barrow 1967) and from Scotland (Scott 1976). Statistical analysis: Correlation and multiple regression analysis was carried out by computer. APPENDIX Two types of multiple regression were used: type 3 SOILS includes all independent variables; type 2 excludes those variables which affect the correlation least The findings of several workers on the Mg status of yellow-brown loams are summarised below: Profiles of Tirau silt loam, Egmont black loam and (under the control termination rule set out in the Mairoa silt loam were sampled to depths of between program). Soil type Depth Mg content in me./100 g soil Ref.:j: Soil group 0.9 and 1.35 m. Details of the profiles are given in subdivision (cm) Mg. Mg,. Total Mg Appendix 1. The soils do not constitute a weathering sequence in the strictest sense because of parent RESULTS AND DISCUSSION Southern Monowai silt loam 0-15 0.6 17.9 62.4 1 material differences. However, the degree of 45.6 1 Te Anau silt loam 4-17 0.7 7.6 weathering and amorphous hydrous oxide contents The results of the chemical analyses (Table 1) and Dunton silt loam 0-10 0.2 3.2 1 the consequent correlation coefficients (Table 2) generally increase in the order Tirau, Egmont, 0-15 0.3--1.0 1.4-2.1 *(18) 1 Central Horotiu silt loam Mairoa. confirm that the amounts of amorphous aluminium, (from Waiteti loamy sand 0-8 1.0 0.9 13.6-25 1,2 iron and associated organic matter are highly 19.2 1 rhyolitic Kereone silt loam 0-19 1.1 1.9 significantly related to sulphate retention. Tamm ashes) Waihou silt loam 0-12 1.2 2.7 25.0 1 Te Puninga silt loam 0-13 1.5 1.4 14.9 1 CHEMICAL METHODS acid oxalate reagent extracts amorphous products of Central Otorohanga silt loam 0-7 3.1 3.3 29.6 1 weathering, and there is little attack on crystalline (from Maihiihi silt loam 0-9 2.2 2.4 35.0 1 Soil analyses were carried out on air-dried soil, minerals (Daly & Binnie 1974), so that the mixed Mairoa silt loam 0-11 0.7 2.3 32.2 1 ground to pass a 2 mm sieve or, in some cases, aluminium and iron are good measures of the 2.2 3.1 24.0 1 tephras) Ohaupo silt loam 0-4 subsamples ground to pass a 0.25 mm sieve. With 'active' forms of these elements. The relationships Dunmore silt loam 0-20 1.6 3.2 19.7 1 between sulphate retention and Tamm extractable Te Kuiti silt loam 0-12 1.0 1.6 36.6 1 the exceptions of pH and % phosphate retention, Kinohaka silt loam 0-7 2.8 2.3 23.4 1 results are quoted correct to the oven-dry weight at aluminium and iron are shown in Figs. 1 and 2. Karaka silt loam 0-18 1.3 4.6 17.7 1 105°C. Full details of the analytical methods are The choice of the colour of the Tamm extract Tirau silt loam 0-8 4.6 0.7 25.0 2 given by Blakemore et al. (1977). However, brief ('Tamm colour') as an index of the blocking effect of Central Ohakune hill soil 0-13 3.6 10.5 64.7 1 descriptions of the methods used in the statistical (from Patua loam 0-8 2.0 3.9 107 1 organic matter was made because this measurement andesitic Egmont black loam 0-10 1.2 5.3 74.6 3 correlations are given below. Additional analyses was the best estimate of organic matter associated tephras) Egmont black loam 0-8 5.4 4.9 75 2 are given in Appendix 2. with the amorphous mineral fraction. If, for all soils, Egmont brown loam 0-8 1.8-3.3 99±23 4 total carbon is plotted against Tamm colour (Fig. 3), Egmont brown loam 0-8 3.1 4.8 1 Acid-oxalate extractable aluminium, iron and it can be seen that there is a good correlation, Patua loam 0-8 2.0 3.9 83 2 organic matter Patua loam 0-10 0.5 3 although there is a suggestion that two relationships Hangatahua gravelly sand 0-10 0.7 63 3 Five g of soil ( <2 mm) together with 10 g acid exist. The Mairoa soil and the top horizon of the (4.4) 93-111 3 Burrell gravelly sand 0-10 0.4-1.8 washed sand was leached with 190 ml of oxalate Egmont profile tend to have more total carbon per Newall gravelly sand 0-10 1.4 79 3 unit of Tamm colour and this is probably related to Norfolk gravelly sand 0-10 0.3 82 3 reagent and made to a final volume of 200 ml (Daly Stratford coarse sandy loam 0-8 0.4-2.0 141±25 4 & Binnie 1974). Aluminium and iron were the state of decomposition of the organic matter. Stratford coarse sandy loam 0-8 1.4 4.9 83-93 1,2 determined by high-temperature flame emission The two groups (a, Mairoa and Egmont 1; b, the rest Stratford coarse sandy loam 0-10 0.1 78 3 spectrometry (Searle & Daly 1977). The optical of the samples) have mean carbon:nitrogen ratios of New Plymouth black loam 0-10 2.1-2.9 5.1 67-85 3 density of the oxalate extract (Ilford 601 filter, 1 cm 18.4 and 12.6 respectively (Appendix 2) and this Inglewood coarse sandy loam 0-10 0.2-2.7 (4.4) 72-135 3 indicates that the organic matter in these soils is less Inglewood coarse sandy loam 0-8 1.3 5.5 1 cell) was measured in an EEL portable colorimeter Inglewood coarse sandy loam 0-8 0.4-2.7 134±20 4 and used as an index of extracted organic matter well decomposed. Consequently there may be less (B.K. Daly, pers. comm.). organic matter associated with the amorphous mineral fraction (per unit of total carbon) in the first *() indicates only one analysis available :j:l-A.J. Metson (pers. comm.) Adsorbed sulphate group of soils. Further confirmation that Tamm 2-N.Z. Soil Bureau Bulletin 26, Part 3 (N.Z. Soil Bureau 1968) colour is a more sensitive indicator of organic matter 3--P.W. Shannon (pers. comm.) Five g of soil ( <2 mm) was shaken for 16 h at associated with amorphous aluminium and iron was 4--M.A. Turner et al. (1978) 20°C with 25 ml of 0.04M Ca(~P04 ) 2 at pH 4.0. confirmed later in multiple regression studies when Sulphate in the filtered extract was determined the multiple regression coefficient increased slightly colorimetrically as methylene blue after Johnson and when Tamm colour was used in preference to total SULPHATE RETENTION STUDIES OF YELLOW-BROWN LOAMS Nishita (1952) reduction and distillation. carbon (r=0.93 and 0.92 respectively). Although Tamm colour was the better index of the organic Sulphate retention,, matter associated with the amorphous colloids, the P. L. Searle complex nature of the soil organic fraction means Two g of soil ( <2 mm) was mixed with 2 g of acid Soil Bureau, D.S.I.R., Lower Hutt that it is not necessarily a good measure of the washed sand and leached with 25 ml of 1000 µg g-1 'organically blocked' anion adsorption sites. It is S solution (as KzS0 ) adjusted to pH 4.6 with 4 true, however, that at high Tamm colour values sodium acetate-acetic acid buffer (Metson & INTRODUCTION characteristics of the soils. The mineralogy of the sulphate retention was generally low (Fig. 4). soils studied is dominated by x-ray amorphous Blakemore 1978). The original leachate was Three profiles of central North Island yellow material. Fifteen separate horizons were examined, collected and recycled through the soil column. The The determination of the relative importance of brown loams were examined to determine the displaying a gradation of organic matter and of acid soil column was left overnight before washing with amorphous aluminium and iron in sulphate retention relative roles of aluminium and iron hydrous oxides oxalate soluble aluminium and iron as determined four 4-ml portions of 70% (VN) ethanol. The is largely confounded by the high correlation and of organic matter in the sulphate retention by Tamm's method (Tamm 1922). The literature leachate was then made to 50 ml with deionised between the quantities of these two elements. Water. In this study the leaching solution contained Multiple regression of sulphate retention (S Ret.) 71 70 sulphate Retention µg g-1 Sulphate Retention 3400 pg g-1 ~6 3400 M6• 3000 3000 M5 ~ • Mt, • 2600 2600 •H3 ~ 2200 2200 •E3 1800 1800 Hz II> !3 1400 Ji ~ 1400 T4 E4 • • 1000 T5 1000 • Ez • 600 GOO E1 • 1, • 200 200 Q-1-~~~~~~~~~~~~~~~~~~~--~~~--~~~~~~~..-~~___, B 9 4 5 6 7 0 2 3 Tamm Extractable Tamm Extractable Iron % Aluminium Figure 2 The relationship between sulphate retention and Tamm extractable iron Figure 1 The relationship between sulphate retention and Tamm extractable aluminium 73 72 sulphate Jletention pg g-1 3600 Total Carbon % Mii 3200 • 17 ~ 16 .Ms 2800 15 14 13 240 ·12 11 2000 10 9 1600 T3 8 • 7 1200 6 1'13 5 •:I, 4 BOO ~ ~6 E2 3 • T2 2 • ~3 !3 400 ,.es £. /JJ1, 0·9 Tamm Colour 0 0·1 0·2 0·3 0·4 5 0·7 0·8 Optical Density Tamm Colour Figure 3 The relationship between total carbon and Tamm colour Optical Density Figure 4 The relationship between sulphate retention and Tamm colour 74 75 Table 1 Soil chemical analyses adsorbed sulphate may be questionable, however, level is indicative of a high capacity to retain further because although the form of sulphate will depend added sulphate. Soil Depth Sym- Sulphate Tamm Tamm col. Adsorbed on soil pH, rates of leaching, organic matter, mmie ool retention extr. (%)* optical sulphate (cm) µg S g-1 Al Fe demity µg S g-1 mineralisation, etc., it is probably largely predeter mined by the other three variables. These Mairoa 0-11 Ml 1440 5.1 2.6 0.900 136 regressions do show, however, the importance of CONCLUSIONS 11-24 M2 1590 8.4 2.3 0.520 279 aluminium, and the strong positive relationship 24-41 M3 2330 . 7.7 2.1 0.205 451 between sulphate retention and adsorbed sulphate The relatively small number of soil horizons 41-57 M4 2780 7.4 1.8 0.205 759 for these soils which is better illustrated in Fig. 5. studied, representing only three soil profiles, means 57--69 MS 2870 7.0 2.1 0.110 1274 These data support the conclusion of Metson and that no unequivocal statements can be made. 69-84 M6 3240 7.4 2.8 0.140 1509 Blakemore (1978) that a high soil adsorbed sulphate However, with the qualification that they apply only Egmont 0-19 El 490 2.2 1.0 0.370 23 19-48 E2 800 4.7 1.1 0.250 61 48-90 E3 2030 6.2 1.7 0.120 239 90-135 E4 1170 2.8 1.0 0.100 98 Sulphate Tirau 0--18 T1 390 3.4 0.6 0.750 55 Retention 18-30 T2 1440 4.6 0.8 0.230 107 pg g-1 30-50 TI 1510 4.6 0.9 0.150 122 50--70 T4 1230 4.1 0.9 0.110 78 70-90 T5 960 3.3 0.7 0.070 27 3400 *Values expressed as % refer to g per 100 g of soil 3000 Table 2 Correlation coefficient matrix between all A type 2 regression on the same data (equation 4) variables decreases the correlation only slightly when iron is omitted from the relationship. 2600 S Ret. = 494 (Al) - 5070 (TC) - 14 (4) Sulphate Tamm Tamm Tamm (type 2, r = 0.950, n = 11) retention alwmmum iron colour Similarly, comparison of the sums of squares of Tamm Al 0.9564**• equations 3 and 4 shows that the effect of iron over 2200 Tamm Fe 0.9343*** 0.8607*** and above that of aluminium is not significant (F = Tamm col. 0.8075** 0.8335** 0.6855* 1.5). ads. sulphate0.8752*** 0.8633*** 0.9345*** 0.8282** The results show that the relative effects of aluminium and iron in sulphate retention cannot be 1800 ***P<0.001 separated, and both elements are probably impor **P<0.01 tant, although in all samples there was more oxalate Hz *P<0.05 extractable aluminium than iron (Table 1). The • (13 degrees of freedom) ~ regressions for the 11 subsoils (equations 3 and 4) 12 ~ may imply that aluminium is the most important 1400 • against Tamm extractable aluminium (Al), iron (Fe) factor in sulphate retention for these samples. The 14 and Tamm colour (TC) for all samples is shown in fact that aluminium becomes less important when • equation 1: the horizons with higher organic matter contents are S Ret. = 154 (Al) + 653 (Fe) - 1591 (TC) + 289 (1) included suggests that the aluminium anion adsorp 1000 tion sites are preferentially blocked by organic ~ (type 3, r = 0.927, n = 15) E;i matter. This implication is further supported by the 'I A type 2 regression excludes aluminium (equation 2) considerably higher correlation coefficient of and a comparison of the sums of squares of types 3 aluminium with Tamm colour compared with the and 2 regressions gives an indication of the effects of 600 ironffamm colour correlation coefficient (Table 2). E1 aluminium on the regression over and above those of •T iron (Professor R.N. Curnow, Applied Statistics If adsorbed sulphate (S) is introduced into the ~ Department, Reading University, pers. comm.). regression as an extra variable then the correlation The Fvalue (1, 11 degrees of freedom) is 3.15, which coefficient increases when all samples are used is not significant. (equation 5) and when only the subsoils are used 200 (equation 6). S Ret. = 989 (Fe) - 1825 (TC) + 653 (2) S Ret. = 124 (Al) + 341 (Fe) - 1024 (TC) + 0.78 (s) + 478 (5) 0 (type 2, r = 0.905, n = 15) (type 3, r = 0.960, n = 15) 0 200 400 600 800 1000 1200 1400 1500 If the soils containing greater than 5% total carbon are arbitrarily excluded from the regression, the S Ret. = 291 (Al) + 103 (Fe) - 2671 (TC) + 0.58 (S) + 301 (6) correlation is improved (equation 3). (type 3, r = 0.971, n = 11) Adsorbed Sulphate SRet. = 339(AI) + 399(Fe) - 3712(TC) +28 (3) In both cases, type 2 regressions show that /Ug g-1 (type 3, r = 0.959, n = 11) aluminium and adsorbed sulphate are the most important variables. The validity of introducing Figure 5 The relationship between sulphate retention and adsorbed sulphate 77 76 BIOLOGY to the soils studied, there is strong evidence to Egmont black loam support the following: Classification: Entic Dystrandept (Soil Taxonomy, Soil 1. The amorphous hydrous oxides of both Survey Staff 1975) FAUNAS OF YELLOW-BROWN LOAMS aluminium and iron are important in sulphate Moderately enleached alvic soil (N.Z. retention. However, those of aluminium are Technical Classification, Taylor & Pohlen 1962) probably more important because they are G.W. Yeates and H.P. McCoU, Soil Bureau, D.S.I.R., Tai.ta Parent material: 0-75 cm Andesitic tephra from Mt Egmont present in greater amounts. (age 10 OOO y) 2. The effectiveness of aluminium colloids to 75-135 cm tephric loess (age <19 850±310 y) Since the sampling of four sites described by Lee populations recorded (Table 1) are remarkably adsorb sulphate decreased compared with those (1959), in which earthworms and arthropods were uniform; this may reflect uniform pasture productiv Drainage: Well drained of iron in the presence of higher amounts of enumerated, there has been no specific study of the ity. In a study of vertical distribution of nematodes organic matter. This suggests that organic Land use: Dairy farming biology of yellow-brown loams. There has been a under pasture (Yeates 1980) in both Egmont brown blocking of adsorption sites occurs predominantly Vegetation: Pasture comprising perennial ryegrass, range of taxonomic studies on soil animals, but loam and Stratford fine sandy loam, 75% of on the aluminium colloids. cocksfoot, yorkshire fog, red and white clover although the Taranaki region has been sampled nematodes in 0-30 cm soil were found in 0-5 cm; 3. High soil adsorbed sulphate levels were there is a dearth of soil information; Stout (1973) this was average for the 11 sites investigated. Profile: A 1 (0-19 cm); (B) (19-48 cm); B3 indicative of a high ability to retain further added (48-90 cm); IIC (90-135 cm) indicates the amount of soil information available. sulphate. The effects of M. hap la and H. trifolii on growth of Investigations of pasture pests are the main source and nitrogen fixation by white clover have been of recent knowledge. When chemical control is widely reported (Yeates 1977, Yeates et al. 1977), APPENDIX 1 SOILS STUDIED investigated (e.g. Dixon & Holland 1977), the but the possible secondary role of fungi has not been Mairoa silt loam physical and chemical conditions in yellow-brown clarified. M. hapla attacks a wide range of plants and Classification: Hydric Dystrandept (Soil Taxonomy, Soil loams may significantly alter the effectiveness of is of economic importance in the commercial growth Tirau silt loam Survey Staff 1975) Classification: Typic Dystrandept (Soil Taxonomy, Soil Moderately to strongly enleached alvic soil certain chemicals (Udy 1977). of poroporo (Solanum aviculare), kiwifruit Survey Staff 1975) (N.Z. Technical Classification, Taylor & (Actinidia chinensis) and various horticultural Moderately enleached alvic soil (N.Z. Pohlen 1962) species (e.g. Dale 1973), and caused termination of Technical Classification, Taylor & Pohlen Parent material: Late Quaternary tephra overlying Hamilton MICROFAUNA trials for commercial production of sugar-beet in 1962) Ash; ages not known but Rotoehu Ash (age Taranaki in the early 1960s. Parent material: 'Tirau ash', comprising a series of rhyolitic 41 700±3500 y) is present at about 80 cm Stout (1978) compared the microfauna of cores of with some possible additions of andesitic ash. from the surface Horotiu sandy loam and Otorohanga silt loam Nematode suppression of predicted fertiliser 0-60 cm 'Rotorua Ash' (age 11 800±150 y) Drainage: Well drained responses is not uncommon. However, an unpre 60-130 cm tephric loess (age not known) irrigated with tapwater or sewage effluent, and 130-160 cm Okareka Tephra (age Land use: Sheep farming compared these results with those for eight other dicted response occurred on a yellow-brown loam at 20 700±450 y) Vegetation: Pasture comprising perennial ryegrass, white soils. Effluent irrigation increased ciliate diversity Waimate West and may reflect depressed popula Drainage: Well drained and subterranean clover, browntop, and abundance in Horotiu sandy loam, a trend tions of M. hapla and H. trifolii at the higher cocksfoot, yorkshire fog fertiliser level (Yeates 1976) Land use: Dairy and intensive sheep farming typical of the three less productive soils whereas in Profile: A (0-11 cm); B (11-24 cm); B 1 1 21 more fertile soils increased saprobity led to the Vegetation: Bracken, cocksfoot, sweet vernal (24-41 cm); B (41-57 cm); B (57--09 cm); 2 22 23 extinction of some species. Tetrahymena pyriformis Table 1 Estimated total nematode populations /m Profile: A 1 (0-18 cm); AB (18-30 cm); (II)B IIB (69-90 cm) (30-50 cm); (II)C (50-70 cm); IIC and Uroleptus musculus were ciliate species not in 0-10 cm soil under grazed pasture (70-90 cm) detected in the effluent but which achieved sizeable populations in effluent-treated cores in both yellow 2 brown loams. In terms of effluent treatment (as Nematodes/m Repli Date Soil ± std error cates measured by the chemical composition of leachates) (thousands) APPENDIX 2 ADDITIONAL SOIL CHEMICAL ANALYSES* Horotiu sandy loam performed relatively poorly while Otorohanga silt loam was amongst the best Oct 73 Egmont brown loam 2890±350 6 (Childs et al. 1977); this is reflected in the ciliate Sept 75 Egmont brown loam 2060±410 5 populations. Soil pH Total Total Total p Tamm Mar 79 Egmont black loam 2400±150 10 phosphorus retention extr. Si Apr 74 Stratford fine sandy loam 2500±150 10 name H 20 carbon nitrogen C/N 1:2.5 (%) (%) (mg%) (%) (%) Sept 75 Stratford fine sandy loam 1950±380 5 NEMATODES Mar 79 Westmere silt loam 1970±230 10 Mairoa 1 5.2 16 1.02 16 188 94 1.1 Pastures on yellow-brown loams contain the root 2 5.4 8.1 0.36 23 57 100 2.3 EARTHWORMS 3 5.5 4.9 0.27 18 47 99 1.9 knot nematode (Meloidogyne hapla) and the 4 5.7 4.1 0.22 19 45 100 2.2 ubiquitous clover cyst nematode (Heterodera trifolii), 100 2.4 According to Lee (1959) the earthworm faunas of 5 5.8 3.3 0.17 19 52 in addition to the potential plant-feeding genera 6 5.6 3.6 0.18 20 54 99 2.5 yellow-brown loams closely resemble those of Tylenchus, Ditylenchus, Helicotylenchus, Paratylen moderately and strongly weathered yellow-brown Tirau 1 5.1 8.5 0.71 12 126 91 1.2 chus, Aphelenchus and Aphelenchoides (Yeates 98 2.4 earths. In forested areas there is a stratified, forest 2 5.9 2.2 0.19 12 61 1975). The occurrence of Dorylaimellus monticolus 3 5.7 1.5 0.12 13 37 97 2.6 earthworm fauna, with leaf mould, topsoil and and/or D. pastura in almost all samples distinguished 4 6.0 1.0 0.09 11 24 97 2.5 subsoil species. The fauna of areas with other than 16 25 92 1.9 yellow-brown loams from other soil groups; their 5 5.7 0.8 0.05 forest vegetation closely parallel those of moderately feeding habits are unknown. The plant-pathogenic, Egmont 1 6.1 6.3 0.45 14 155 80 0.8 and strongly weathered yellow-brown earths with 2 6.6 3.2 0.29 11 186 99 2.1 virus vector nematodes Trichodorus (on apple) and similar vegetation. The distribution of earthworm 3 6.6 1.5 0.13 12 117 99 2.5 Longidorus (pasture and luceme) have also been 4 6.4 1.0 0.07 14 77 92 1.4 reported. species in the upper North Island (Lee 1959) reflects volcanic activity, sea level changes, vegetational *Values expressed as % refer to 65 per 100 g with the exception of phosphate retention Although there is normally marked seasonal changes and mountain barriers. No soil differences where % refers to the proportion of added phosphorus adsorbed by the soil. variation in nematode populations, the pasture per se appear involved. 78 79 In terms of populations, Lee (1968) reported a the sward reduced its subsequent production by 65% observation, with the numbers and volumes of large earthworm population in 0-7 .5 cm Tirau silt (Thomson et al. 1978). Engl~sh soils, Oades and Jenkinson (1979) and organisms converted to weight by appropriate loam under good pasture (Allolobophora caliginosa ~eing Jenkmson et al. (1979) found that the biomass In a recent revision of this group, McColl (in factors. ThIS approach is still very valuable but is and Lumbricus rubellus in the proportion of 2:1) ClA TP ratio was fairly constant and averaged about press) examined litter and humus samples from technically difficult and tedious. A marked stimulus while Egmont black loam (A. caliginosa and L. 13~. In ~hese samples of yellow-brown loams, this indigenous vegetation on yellow-brown loams at to the study of has been given by rubellus) and Patua loam (no earthworms) under micr<;>bi~l biom~ss ratio vaned from 126 to 241; similar variations have various sites. One species the development of mdirect, biochemical estimates poor pasture had significantly fewer earthworms. A (Paratrochus curvisetis) been found in other New Zealand soils from was found almost exclusively (Mt Messenger being such as measurements of biomass C or adenosine 5 '~ native megascolecid earthworm (Diporochaeta grasslands (unpublished data). These variations in triphosphate (ATP) contents. These values are obtusa) was found under regenerating forest. the exception) in litter on such soils. Five further the ATP content of the microbial biomass may be species were found at other localities (for details of converted to microbial biomass by the use of factors partly caused by differences in the nature and When sampling Egmont black loam under good localities see McColl 1981) on yellow-brown loams; d~veloped ;-ivith pure cultures of soil-inhabiting metabolic state of the microbial populations in the pasture in March 1979, H.P. McColl (unpublished P. vagepunctus (Mt Egmont); P. tricarinatus m1cro-orgamsms. As part of a wider biochemical different soils. data) found that of an earthworm population of four (Pouakai saddle and Stratford); P. microphthalmus study of soils under grassland and various land use million/ha, 86% were juvenile A. caliginosa. (Meremere); P. hermes (Bushy Park, Kai-iwi); and practices, we have measured microbial biomass in The effect of cropping on the microbial biomass is Sexually mature A. longa made up 12.7%, and the P. scapulifer (several localities on Mt Egmont, the topsoil of four yellow-brown loams. shown by the Horotiu samples. Here the levels of remainder were juvenile L. rubellus. The composi Pouakai saddle, Stratford, Okaiawa, and Mere microbial biomass declined more rapidly than did All soils were sampled (0-8 cm depth) under tion of population and species is thought to reflect mere). Kamahi was the main plant species at most total organ~c. ~att_er cc:ntent (Table 2). Generally, grazed, int~odu~ed grass-clover pastures (Table 1). responses to climatic variations, as the pasture was sites, with cedar, rimu, pepperwood, five-finger, enzyme activities m soil under maize also fell more The Horotm soil was also sampled in areas that had sampled after several days of rain following a period mahoe, tree ferns and ferns present at some. The rapidly. than did total C content (Ross & Cairns been cropped with maize continuously for several of drought. Similar results were obtained from plant species contributing to the litter appears to u~publ~shed_ data). Maize cropping also lowered years. Three replicate samples, each of 20-30 cores, Westmere silt loam, though L. rubellus was absent have a much greater influence on the distribution of m1c~ob1~l b10mass and biochemical activities in were ta~en of each soil; the soil was sieved through a and the population slightly lower (3.8 million/ha). these beetles, than the underlying soil type (McColl Pumu ~1lty clay loam, a central gley soil in Waikato 2 mm sieve before the biochemical analyses. All These population densities are about average for 1981). (Cotchmg et al. 1979). In both the Horotiu and the results, except pH, are presented on an oven-dry New Zealand soils. Pu~i~. soils, le_vels of microbial biomass and enzyme (105°C) soil weight basis. Table 1 shows that the Argentine stem weevil (Hyperodes bonariensis) act1v1tles provided much more sensitive indicators of Under Stratford fine sandy loam at the Ministry of samr:iles were slightly or moderately acid, with changes in organic matter on cultivation than did Agriculture and Fisheries demonstration farm at This widespread pathogen of ryegrass also attacks medmm contents of total C, medium to high total C contents. Stratford, J.A. Springett (pers. comm.) found seedling maize in Horotiu sandy loam (Watson & contents of total N, and generally low C/N ratios In spite of several biochemical similarities the Octolasium cyaneum and a large native species Wrenn 1978). Satisfactory control in maize was (Blakemore et al. 1977). C02 production was (probably Octochaetus multiporus) in addition to the obtained when pasture was cultivated 4-5 weeks generally moderately high. The Horotiu soil ;.mder Horotiu and the Puniu soils differed in ~ther three mentioned above. before sowing; preplant chemical control was also maize had much lower contents of organic matter, respects, the most striking being in their relative successful. and a lower rate of co2 production, than it did contents of organic matter and microbial biomass. under pasture. Total C contents were higher in the Horotiu than in ARTHROPODS Soldier fly (Inopus rubriceps) the corresponding Puniu samples (which contained Values for biomass_ C and mineral-N (Min-N) 7.8% ~nd 3.6% total C under pasture and maize Grass grub (Costelytra zealandica) Much of the New Zealand work on this pasture fl~sh w~re rather low m the Waiteti soil, and much respectively), whereas the microbial biomass values pest has been carried out by Ministry of Agriculture higher_ I~ the other three soils under pasture (Table were higher in the Puniu than in the Horotiu Emergence of adult beetles and abundance of 2). This is reflected in the ratios of biomass C/total C and Fisheries at Matangi, near Hamilton, and Dixon s~mples. In the Puniu soil, the ratios (%) for grass grub larvae in Horotiu sandy loam have been & Holland (1977) identify the soil as Bruntwood silt and Min-N flush/total N which were also lowest in btomas~ C/total C wer_e 3.3 and 1.7 under pasture followed by Henzel! and Lauren (1977). However, loam. Trials have shown populations may be t~e Waiteti soil. We do not know why these soils and maize, and the ratios (%) for Min-N flush/total much of the grass grub work has been carried out in managed through maintaining short pasture which differ, ~ut !t is_p?ssible that the low clay contem of ~ _were 4.4 and 2.1 respectively. These results glasshouse flats or in field areas for which soil type is reduces oviposition (Prestidge 1978), heavy stocking the Waitetl so11 1s part of the explanation. md1cate that the Horotiu soil contained more of its not given. reducing oviposition sites (Dixon & Gerard 1979), A TP conte~t was rather high in all pasture organic matter in a relatively inert state than did the and use of isophenphos or carbofuran as seed and it was not related directly to their Puniu soil. Other unpublished results with soils Manuka beetle (Pyronota spp.) sampl~s, treatments (Dixon & Holland 1977). Heavier organic matter content. In several Australian and u!lder grassland have, however, shown that the In Taranaki, larvae of these beetles cause pasture stocking, by sheep or cattle, depresses larval b10mass C/total C and Min-N flush/total N ratios of population of I. rubriceps (Dixon & Campbell 1978). damage similar to that of grass grub larvae. Table 1 Some properties of the samples Organophosphate insecticides appear effective in Control measures using cultivation against argen controlling larvae, but care must be taken to avoid tine stem weevil, and stock treading against soldier selectivity when both Pyronota and Costelytra larvae fly and manuka beetle, reflect the physical Totlll Totlll Particle size C0 Soil name Vegetation Moisture 2 are present. While cattle treading reduced larvae properties of yellow-brown loams which make such pH c N C/N (%)t (pmolg·l 2 (%) populations from 96 to 45/m the treading damage to measures feasible. (%) (%) Sand Silt Clay soil s-l)tt Egmont black loam Pasture 60 5.9 8.8 0.81 11 40 40 20 40 Tirau silt loam Pasture 65 5.9 9.9 0.95 11 35 52 13 56 Waiteti loamy sand Pasture MICROBIAL BIOMASS OF SOME YELLOW-BROWN LOAMS UNDER PASTURE AND 70 5.6 8.8 0.63 14 49 47 4 71 Horotiu silt loam• Pasture 68 6.3 10.1 0.97 10 43 32 25 72 MAIZE CULTIVATION Maize at 52 6.3 6.0 0.53 11 n.d. n.d. n.d. 17 Maize bt 47 5.4 5.8 0.58 10 55 24 21 16 D.J. Ross and K.R. Tate, Soil Bureau, D.S.I.R., Lower Hutt n.d.-not determined •All H?rot!u soil samples were taken from the locations studied by Cotching et al. (1979). Particle size f;~~)~mations were made followmg treatment of the soils with hydrogen peroxide (Churchman & Tate The importance of the soil microbial biomass as a the activity of its component organisms is essential in component of the ecosystem is being increasingly the general cycling of plant nutrients. Until recently, ta, b--maize grown for 8 and 11 years respectively recognised. Although microbial biomass is not this biomass (the weight of living micro-organisms in tDeterminations based on the procedure of Thomas (1973) necessarily related directly to the fertility of a soil, ttDetermined at 25°C on Biometer flasks over the period when the rate of CO production was most soil) was generally determined by direct microscopic constant 2 r I 81 80 therefore unlikely that allophane in these f'ello:" these yellow-brown loams under. pasture were brown loams was restricting the level of m1crob1al (except for the Waiteti soil) not part1cular~y low, b~t biomass or its general metabolic activity. rather that the Puniu values were high. It is AGRICULTURE ON WAIKATO YELLOW~BROWN LOAMS Table 2 Biomass C, Mineral-N flush and ATP contents B.A.J. Smith. Min-N Biomass Biomass Min-N ATP Biomass Farm Advisory Officer, Ministry of. Agriculture & Fisheries, Hamilton c (µ,g g:-' flush (µ,g g-1 __c_(%) flush~) Soil name Vegetation c ATP soil)t (µ,g g-1 soil)tt Total C Total soil):j: The yellow-brown loams of the Waikato cover autumn if these periods are at all dry. Since 1970, much of the Waikato Basin from Huntly in the north summer dry spells have been common and pasture 7.1 1.9 2.0 241 Pasture 1710 158 Egmont black loam 9.5 2.3 2.1 238 to the northern King Country in the south. Although production has been reduced. Pasture 2260 220 Tirau silt loam 6.1 0.9 1.2 126 small areas occur in the coastal hill country the main Pasture 770 60 Stocking rates average 2.5 cows/ha, with better Waiteti loamy sand 12.8 2.2 2.5 17 Pasture 2170 238 western boundary is Pirongia and the eastern Horotiu silt loam 3.4 1.0 1.0 174 managed properties reaching 3 cows/ha. Where at Maize a 590 49 boundary the Kaimai Range. Altogether they cover 4.2 0.7 0.7 94 least 90% of a farm consists of a yellow-brown loam, Maize b 390 35 an area of at least 400 OOO ha. production may reach 450 kg/ha of milkfat annually, · · h d f Jenkinson and Powlson (1976), Ayanaba et al. (197.6), They form the major soil group in the Waikato but the average production is more likely to be 0 0 t, :j:, tt Determmat1ons based on the met. t . h cedure of Jenkinson and Oades for estimatmg Basin where they are farmed in association with 300 kg. Much higher production figures are reached and Jenkinson and Oades (1979) respective y, : e .pro f acid concentration to 0.008M in the A TP was modified by increasing the ethylenediamme tetra-ace ic either organic peats or gleys. In Waipa County, 61 % on farms which have a higher proportion of gley or buffer (Tate unpublished data). . . f . 'th hloroform inoculation with a little fresh of the soils are yellow-brown loams, but there are even organic soils, the former being more fertile and :j:Increase in mineral-N produced after fumigation o s01 1 w1 c , few farms which consist only of this soil group. The the latter less affected by dry weather. soil, and subsequent incubation. hill country areas to the north, west and south are With good management and adequate fertiliser, not nearly so dominantly yellow-brown loams pasture production levels of 13 OOO kg DM/ha can be because on the steeper slopes the ash cover has been achieved on the yellow-brown loams, unless growth eroded, mainly by water, and deposited on the lower is hindered by lack of moisture in the summer slopes and valleys. On hill country there may be only auturnn period. a thin ash cover, over the underlying parent material of mudstone, sandstone, limestone, basalt or Pastures consist of ryegrass, white clover and greywacke. cocksfoot with prairie grass prominent where soil fertility is higher. Paspalum can become a dominant species under lax grazing in the summer, while Poa FARMING TYPES spp. may also be prominent in the early spring. The flat to easy rolling country in the Waikato Ragwort (Senecio spp.), docks (Rumex spp.), Basin is used principally for dairying, although there chickweed (Stellaria media, Cerastium spp.), and are sheep and beef farms scattered throughout the storksbill (Erodiumspp.) are the most common area. Since 1970 there has been an increasingly weeds, the last two being more prominent after a dry larger area sown in maize for grain, although maize summer when pasture growth is limited. Ragwort is is grown on other soils as well as yellow-brown more of a problem on areas where pasture is weak loams. Because of the effect of returns and prices the and cannot be cultivated or mowed. area in maize has now stabilised. During the last five Provided adequate provision is made for sup years there have been a large number of subdivisions plementary feed by conserving surplus grass for to 4-ha blocks, and this has tended to push dairying silage or hay, there is little need for a supplementary on to some of the more broken and steeper country. crop for a dry summer and even less need for one in Although rural subdivision is now closely controlled, the winter. In fact, as stocking rates and soil fertility there are many small blocks surveyed but not yet rise, there is a lesser need for hay and silage for subdivided. Farming of these blocks does not winter feed. necessarily mean a loss of production, although the type of product may change. The only real place for a crop is in a pasture renewal programme, but even here, the introduction of new species by underdrilling, with or without DAIRYING chemical ploughing, is quite satisfactory. The introduction of new species is usually limited to Because of their topography, their free-draining either Nui or Mangere ryegrasses for improved nature and the ease with which they can be worked, summer pasture production. In general, pastures the yellow-brown loams are well suited to dairying. tend to revert to the species which suit the stocking These characteristics were recognised from the first rate and management regime imposed upon them. days of settlement. This, together with the closeness Correct fertiliser usage and good stock and pasture of markets in Auckland and Hamilton, led in the late management are often the cheapest and quickest 1800s to dairying becoming the major farming ways to improve pastures. Occupation. Topdressing on dairy farms on yellow-brown Production from these soils is not high, due to loams has been regular, with an increase in the Pasture growth limitations in the late summer and amount of potash used during the last 20 years. This 83 82 nd black beetle, but none of them do sufficient berry crops continues to grow, dairying is likely to has often been excessive. Increasing costs of both potatoes, cabbages, cauliflowers and lettuce (see Horticulture section in this volume). ~a:cnage to warrant treatment on hill country. continue to be the major farming system. The fertiliser and spreading are forcing farmers to Generally treatment is not practicable. emphasis, however, may change from factory supply evaluate their topdressing programmes and adopt farms for dairy products to more town milk While cropping on the Waikato yellow-brown more rational systems. MAIZE ·production. loams will increase, especially if soybeans, sunflow On established dairy farms with good pasture ers and similar temperate-zone crops become The productive capacity of the hill country should Since 1970 the maize area has developed rapidly, species and satisfactory levels of produ~tion.' with a established and the need for vegetable process and not be overlooked as well. stocking rate of at least 2.5 cows/ha, 1f sod test P mainly on larger sheep and cattle properties, or on a levels are low a rate of 400 kg/ha of superphosphate few properties which grow. maize a.lone. In ~?st is desirable. Where the K soil test is also low to cases soil type is not the mam factor m determmmg medium, 125 kg/ha of muriate of potash. is whether or not maize is grown. necessary. If soil test levels for P and K are medium The fertiliser requirements for maize on the AGRICULTURE ON TARANAKI LOAMS to high the phosphate dressing can be reduced to yellow-brown loams are not clear cut and depend 250-300 kg/ha of superphosphate and 40-50 kg/ha largely upon how many maize crops have been taken of muriate of potash. These dressings are usually B.J. from the area. applied as a 30% potassic supe.r mixture, alt~ough Farm Advisory Officer, Ministry of Agriculture & Fisheries, New Plymouth 15% and 50% potassic super mixtures are available First year crops out of good pasture nee? only a and are used where appropriate. If topdressing has base dressing of 500 kg/ha of 30% potass1c super been neglected in the past and soil test levels are pre-plant, together with 110-150 kg/ha of a com Tourist publicity on Taranaki almost inevitably Pasture production is commonly about 12 OOO kg very low, increases in the above rates are necessary. pound N.P.K. 12-12-12 with the seed. features Mt Egmont and Jersey cows, and DM/ha per year, with good average production traditionally Taranaki agriculture is heavily iden levels at about 340 kg milk fat (MF)/ha, and With reasonable fertility, one annual topdressing Subsequent crops generally respond to increasing tified with dairy farming. While being a misrepresen 145 kg/cow, with a stocking rate of 2.2 cow is quite satisfactory, usually in the autumn, altho~gh rates of N, P, or K, with N as a side-dressing being tation of the total Taranaki land area, this picture is equivalents/ha. At the upper levels the Waimate many farmers topdress twice a year, applyu~g economic after the first year. a relatively true description of that part of Taranaki West Demonstration Farm at Manaia has achieved superphosphate in the autumn and a potass1c occupied by the yellow-brown loams, that is the area over 550 kg MF/ha, carrying 4.1 cows/ha. superphosphate in the spring. in the immediate radius of Mt Egmont. Here the SHEEP AND BEEF land use is predominantly dairy farming so that this A major problem of dairy farmers on the yellow Lime is being used in increasing amounts brown loams is the depredation of pastures caused is the major feature of the agricultural use of these following the results of lime trials ~n ~he no~the~n Throughout the dairying area there are many soils. However, other uses do exist. Interspersed by the larvae of grass grub (Costelytra zealandica), King Country. Evidence from similar soils m sheep and beef units, usually over 80 h.a. area and with dairying are fat lamb and intensive beef farms, the light free draining nature of the soils providing Taranaki indicates an increase in summer and them with an ideal habitat. Facial eczema, caused by held by old established and debt-free fam1h.es. These particularly on the more undulating country. On the autumn pasture growth where there is ~ response to properties breed and fatten lambs and buy m weaner the spores of the fungus Pithomyces chartarum can lime. Although it may not always give a growth generally frost-free coastal strips from Urenui to cattle to fatten to 20 months. In the hill country, on Oakura in the north, and Opunake to Patea in the also cause problems with stock health in the warmer response in the Waikato, lime may improve pasture areas. the west coast, few farms have large areas of yellow south, an increasing diversification to cash cropping palatability. brown loams. Most of the ash has been washed off and horticulture is taking place. Furthermore, to the There are no trace element deficiencies. Artificial and deposited on the easy slopes and valley floors. east of Stratford and Inglewood, on Stratford hill nitrogen is widely used in the late winter and early While many of these properties are capable of soils, the predominant farming pattern is that of spring, either as urea at 60-70 kg/ha or sulphate of fattening both sheep and cattle, most of them, more extensively grazed store sheep and beef cattle ammonia at 125 kg/ha. Some advisors feel that together with the steeper country, are used for store hill country units, this land use being dictated largely SHEEP AND BEEF FARMING doubling the rate will give more than double the stock production. by the topography. response. Carrying capacities range from 7 to 17 stock Intensive fattening/finishing units/ha depending on the topography, area and Fat lamb production is based on Romney and The main insect pests are grass grub and soldier fly DAIRY FARMING but these are seldom a real problem and are only quality of pasture and management. Pasture Romney-derived ewes (Coopworth, Perendale) with production varies from 4000 kg DM/ha from poor generally a fat lamb terminal sire being used and rarely treated. The majority of dairy farms are 50-65 ha, running browntop-dominant swards to 12 OOO kg/ha on the replacements purchased, although many farmers do about 100-140 cows plus replacements. Major stock problems are metabol~c diseases-: better ash country from good ryegrass and white breed their own replacements, thus using more than grass staggers and milk fever-and facial eczema m clover pastures. The predominant breed is still the Jersey although one breed of sire. As this type of farming is generally eczema-prome years. Unlike the dairying country, the soils of the ~ill the Friesian has gained in popularity over the last 15 confined to the easier undulating country, lambing Dairying is highly profitable and this is shown by country are much more varied so that topdr.essmg years (1979 L.I.A. artificial matings Taranaki: 51 % percentages generally exceed 100 with stocking rates in the order of 14 L.S. U./ha. the largelyunsatisfiedannual demand for farms bo:h tends to be done with the fertiliser which suits t~e Jersey, 43 % Friesian). for purchase and for sharemilking. The gross margm major soil type of a property, rather than what is Dairy farn1ing is based almost exclusively on Cattle and sheep grazing are generally integrated return per cow, at 2 .5 cows/ha in 1979/80 is needed by individual soil types. It is much mo~e Pasture, fed on a rotational basis with the general on a rotational system. In the main, cattle are beef estimated to be $207.00 and per hectare $520.00. likely to be applied by aerial topdressing and 15 Pattern being a 10-30 day rotation during the breeds usually purchased as weaners, or to a lesser usually a maintenance rate of 350-400 kg/ha of tnilking season, and a strip- or break-grazing system extent 12-18 months of age, from hill country superphosphate applied once a year. Hay paddoc~s over the winter accompanied with the feeding of hay properties. These are then sold prime, usually at 20- HORTICULTURE usually receive an annual dressing of 30% potassic and/or silage supplements conserved from the spring 30 months old. super at 500 kg/ha from ground applications. and summer. For the same reasons that they are suitable for With an increasing Friesian component in dairy dairying, the yellow-brown loams are . becoming On the hill country the major weeds of the yellow· The generally free draining nature of the soils suits farming, dairy beef production from Friesian and popular for horticulture, although there is also :he brown loams are nodding thistl~ ( Carduus n.utans )d Winter pasture management, but can lead to Friesian crosses has also become a significant part of fact that they are the major soil group close to maJor winged thistle (Carduus tenwflorus), vanegate Problems during a summer dry spell. Fortunately, beef production. These cattle are raised as bulls or population areas and consequent demand. Crops thistle (Silybum marianum) and ragwort this is infrequent, and there is a relatively evenly steers, in specialised units or in conjunction with such as berries-strawberries, raspberries and ( Senecio spp.). spaced rainfall which encourages good all year round dairy or fat lamb enterprises. Again slaughter is boysenberries-sweet corn, and asparagus are being Insect pests include grass grub, porina, soldier fly grass growth and hence reliable dairy production. generally at 18 months to two years old. grown as well as the normal vegetable crops- 84 85 Store sheep and cattle and the increased relative profitability of sheep The farming systems on the hill country are typical have resulted in an overall decline in cattle numbers.' LIME USE AND ANIMAL PRODUCTION IN of the whole of the North Island of New Zealand. KING COUNTRY On Taranaki hill soils, high rainfall and low natural fertility mean that reversion of pasture to fem and ARABLE FARMING AND HORTICULTURE M.R.J. Toxopeus manuka are major problems, and grazing and Rualmra Agricultural Research Centre, Hamilton topdressing policies are basically designed to Taranaki has traditionally been a pastoral farming area. However, the Taranaki yellow-brown loams counteract this. Pasture quality generally is poorer, INTRODUCTION with browntop being the dominant species. Sweet because of their structure, workability and generan; GRAZING EXPERIMENT free draining characteristics, are ideally suited to a vernal, crested dogstail and Danthonia are also The King Country region is mainly pastoral. It wide range of arable and horticultural crops. The primary aim was to record animal liveweight, significant components of the sward with subterra ranges from Taumarunui and Ohura in the south to Favourable climatic and topographical features also and other tangible changes in stock, pasture and soil nean clover and Lotus spp. being the predominant Qtorohanga in the north, with Te Kuiti as its centre. exist on a significant area of these soils. An in a simple duplicated comparison of control legumes. Because of the poorer pasture, associated The Rangitoto Range forms the eastern boundary. versu~ exception is wind, and no horticultural enterprise in lime. A minimum of six sites would be used for at animal production is also generally poor, an 85% The topography can be likened to a broad horseshoe particular is safe without extensive shelter. least three years each, to allow full development of lambing being typical. Stocking rates also are low, of steep hill country opening to the north, enclosing any response and to consolidate overall management generally around 7-10 S.U./ha. On the easier hills, Establishment of grain drying facilities in both the undulating land and nlleys where the yellow of the scattered replicates. Each site was 8 to 10 ha especially where there is some associated flat land North and South Taranaki have encouraged grain brown loams prevail. These soils developed in mixed usually subdivided into a latin square design. ' all, performance levels are generally better than production with generally 2000-2500 ha being sown andesite and rhyolite ash of Late Quaternary origin those quoted and some stock is generally fattened in each year, mainly wheat, barley and maize. (>40 OOO years ago), and are much older than the The soils were sampled before the start of each these situations. A recent development in North Taranaki was yellow-brown pumice soils from rhyolitic pumice s~aso~ to a depth of 30 cm. Site descriptions are Farming systems on this hill country are typified cultivation of 1000 ha of Solanum aviculare (the (deposited some 1600 years ago) that occur toward given m Table 1, and data on the profiles in Table 2. by the low-cost approach with minimal topdressing native poro poro), for the extraction of steroids for the eastern boundaries of the region. All sites had a yellow-brown loam cover of at least 50 cm. and little or no reliance on winter supplementary the pharmaceutical industry. Vegetable growing is On volcanic ash soils generally the need for lime feed. The grazing system is traditionally set stocking, based mainly on local markern with about 200 ha to enhance livestock production has been a long Lime was applied once only, at 2.5 t/ha broadcast but in recent years, associated with the iptroduction under cultivation and a further approximately 50 ha standing subject for debate, made all the more by a commercial operator under weather conditions of low-cost fencing, various systems of rotational in fruit production, mainly sub-tropicals. Expansion subjective by the easy access near Te Kuiti to high carefully chosen to minimise drift. The application grazing have become more significant. General in these fields is proceeding rapidly. A further grade limestone deposits. was usually made a few months before lambing farming policy is one of running breeding ewes and horticultural use is the 200 ha of nurseries, started in August. breeding cows with store lambs and weaners being producing stock for both New Zealand and export However, based on rather static local sales over sold for fattening elsewhere. Because of the consumption. the Ia.st decade of some 3000 t/year (total output of Pa~tu7e on the sites was the typical hill country reversion problems mentioned, cattle/sheep ratios quarnes 250 OOO t/year) of ground limestone for associat10n of: co-dominant browntop (Agrostis tend to be high. However, in recent years, high For further reading on farming in Taranaki see pasture topdressing, at an average rate of 1-2 t/ha spp.), yorkshire fog (Holcus lanatus L.), perennial cattle losses due to adverse seasonal pasture growth, Ministry of Agriculture and Fisheries (1977). every 3-5 years, it is conservatively estimated that of ryegrass (Lolium perenne L.); sub-dominant goose t~e nearly 2300 farms in the region only 70 (3%) use grass(Bromus mollis L.), sweet vernal (Anthoxan hme regularly. These constitute the hard core of thum odoratum L.), white clover (Trifolium repens FARl\1.ING ON THE YELLOW-BROWN LOAMS-MANAWATU AREA mainly dairy farmers who are convinced of its L.), crested dogstail (Cynosurus cristatus L.); some ~e~efi~s, while the majority either see no need, by other grasses and legumes, flatweeds, thistles and P.R. Hockey ~1;mg m the midst of limestone country, 'can't afford other weeds. Pasture vigour varied with fertiliser Senior Advisory Officer tt , or are advised against it. history, which ranged from 200 to 400 kg/ha of superphosphate per year. Ministry of Agriculture and Fisheries, Palmerston. North Ministry of Agriculture advisors do not actively Much of the yellow-brown loam soils and their seed production. An occasional grass seed crop is promote lime, being guided by past field trials on . Dry matter production was measured at monthly intergrades in the Manawatu are in the Kiwitea grown on the terraces and market gardening is being ~~~11 plots. The last series of trials in the region was mtervals under cages which were also used for Kimbolton area, with some around Dannevirke and attempted on a small scale. initiated in 1970 and yielded occasional dry matter chemical and botanical composition samples. At a responses of up to 20%, but mainly at the highest Levin. late~ stage, in-field estimates of standing height, Pasture problems revolve mainly around Porina rates of 5 and 10 t/ha. No molybdenum release or ~razmg pattern and botanical composition were In these areas, on the hills, sheep and cattle on the hill country and grass grub on the rolling and manganese toxicity correction was involved nor was mtroduced as a complementary technique. grazing is the predominant use. The soils are free terrace country. an improvement found in botanical com~osition. draining, farmed under cool winters and generally The overall result was considered uneconomic. . The molybdenum status was tested in small plot Californian thistle is one of the major pasture tnals scattered over the site for one year. adequate rainfall well spread over the year. weeds on these free draining soils. By contrast, convinced users of lime have tended The carrying capacity is around 12-14 S.U./ha, to. discount pasture production or composition Lambs born from two-year-old ewes were There are no known problems with trace elements producing good quality stock with few health Criteria in the short term, and claimed a noticeably selected. At the beginning of each season the ewes although copper deficiency is sometimes suspect. problems. Very few problems with facial eczema and rapid improvement in stock thrift and pasture were sorted by stratified randomisation and stocked at about 15/ha. From marking* onwards, some four good pasture growth have the potential to produce Generally, fertiliser programmes comprise 250- Palatability instead. Ironically, such claims nearly all good stock with high production. 375 kg/ha of superphosphate ground spread or flown came from farmers on volcanic ash soils outside the weeks af~er lambing, all animals were weighed at onto the steeper hills. On the dairying land, annual I Table 3 Progress summary (all weights in kg) duplicate plots. On some farms cattle were added in Soil late spring to keep down growth; elsewhere sheep Lime increased pH by 0.2-0.3 units, with the were used to clean up after the lambs had been Yew: 2 Year 4 effect apparently undiminished four years after Year 1* Yew: 3 shifted. + + + + application. The raw field data indicate that the lime lime lime lime All other usual farm operations including the main pH change (up to 6.0-6.2) is still in the upper 4 cm of soil, with no downward movement beyond fertiliser programme were continued by the owners Soil: who also assisted with the experiment. 7.5 cm depth. pH (0-7.5 cm depth) 5.6 5.8 5.6 5.9 5.7 5.9 5.7 5.9 % Ca saturation of ECEC 80 85 ,79 86 80 87 79 89 Because of its scale the project developed Similarly, the increased calcium proportion of the Effective CEC (raised from 80% to 85% and rising) Pasture: gradually, and the last site is only now operational, Yield (DM/ha, - OOO) 13 +2% 10 +6% 12 +12% 10 +20% while two earlier sites have been finished. In suggests a long term residual liming effect. Clover content (%) 14 17 18 20 15 17 19 27 addition, one replicate was completed on a yellow Ca!P (of % in DM)t 1.9 2.3 1.8 2.4 2.1 2.4 2.2 2.5 Exchangeable aluminium, determined for three brown pumice soil near Taupo by local advisory sites some three years after the lime was applied, Animal: staff. Ewe L.W. at marking; 45.2 45.0 44.4 44.6 40.9 41.6 48.4 50.3 showed some variation but was not high, at 0. 70 Gain at weaning 5.2 294% 6.5 0% 6.4 +23% 3.4 +3% me./100 g and was reduced by liming to 0.37 me.% Total ewe + lamb L.W. RESULTS AND TRENDS (D.C. Edmeades, pers. comm.). The ratio Al/ECEC (at weaning, kg/ha) 1030 -1% 1070 +2% 1040 +3% 1020 +7% (control 0.07, +lime 0.02) was well below 0.1 and at Lamb L.W. at marking; 9.0 9.0 10.3 10.5 9.2 11.0 11.3 Although each site must strictly be regarded as a Overall gain (by autumn) 25.6 -7% 17.9 +5% 19.9 +12% 14.7 +14% these levels Al toxicity in legumes would not be replicate within the project, each developed as a Wool (greasy) 1.43 +1% 1.03 +2% 1.16 +9% 0.82 +7% expected (Kamprath 1970). separate entity due to differing paddock size and 'Drafting' potential (% H 62 62 60 70 51 61 53 58 shape, climate, starting date, pasture growth, These were the only marked changes found in the Mean L. W. of draft 29 +3% 28.6 +2% 28.6 +1% 28.1 +4% stocking rate, breed and condition, and not least, soil test, and even the C/N ratio showed virtually no individual farm management. change. *Means generally derived from: 5 sites (year 1), 3 sites (years 2 and 3), 2 sites (year 4) tindividual Ca and P values within normal range for pasture growth The project will need another year or two before :j:>25 kg L.W.; average of 3 months, Dec.-Feb. (incl. weaning) Pasture statistical work can commence, so only the main effects can be used at this stage to consider trends. The average production levels and responses These should suffice as most events to be discussed shown in Table 3 give a fair illustration of the did tend to develop commonly at all sites. In Table 3 gradually increasing difference between treatments the results are set out by year and under three main observed over the years. The mean responses in years three (m=3) and four (m=2) would be Animal headings. regarded as well worthwhile in mowing trials, and expected to influence animal production. They are As the experiment progressed it was found useful expected to reach statistical significance. The to separate the animal production data into the site descriptions (soils to 7.5 cm depth) Table 1 Project FF 180: responses, although not always seen as a change in liveweight change before and after weaning, as well sward colour, were only prominent from late spring as look at the total gain of the lamb. Over the first C/N p to autumn. Whether these were due to a change in phase the ewe liveweights were taken after marking Serial Location Area Soil no. & type* pH Exch. cations (me./100 g soil) BS C11(%t c N (%) no. (ha) Ca Mg K Na TEB CEC (%) ECEC) (%) soil moisture during dry summers was not to avoid negative gains due to the drop in weight thoroughly tested. when lambing, without sacrificing the uniformity 18 4 obtained at the start of each year. At weaning, it can 1175 Mairoa 6.0 63 Mairoa si. I. 5.5 7.9 1.29 0.80 0.29 10.3 64.1 16 76 22.1 1.22 Clover content in the pasture increased on some be seen that lime did not tend to have a marked (4 yrs) over greywacke sites from year one onwards, but varied or decreased 19.5 7 effect on the liveweight gain of the ewe but that 2176 Mairoa 7.4 63aWaitanguruf.sa. l. 5.6 8.3 1.28 0.61 0.25 10.4 60.8 17 79 on others, though the means calculated suggest a there was some effect on that of the lamb, from the (4th yr) over limestone positive change overall. 17 7 3176 Rangitoto 10.5 60 Te Kuiti f. sa. l. 5.7 12.1 1.81 0.61 0.26 14.8 65.6 23 82 19.3 1.13 rising trend of the response in total weight of stock (3 yrs) over greywacke The mineral constituents of the mixed herbage carried at that time. 17.9 2.85 1.00 0.23 22.0 64.4 34 82 15.8 1.00 16 8 were generally satisfactory for growth. Lime showed 5178 Rangitoto 10.1 59c Maihiihi sa. 1. 6.2 The total weight (control) at weaning also showed (2nd yr) over greywacke the expected tendency to lower manganese and to 17 11 an interesting uniformity between years. 6178 Pakeho 8.0 62dh Pomarangai si.1. 5.6 I 7.7 1.24 0.66 0.26 9.9 62.4 16 79 19.0 1.15 raise molybdenum levels, but both remained inside (2nd yr) over greywacke their normally observed range of 50-200 ppm and The trend of lime increasing lamb production is 0.5-2 ppm respectively. The check plots established also reflected by the estimates of drafting potential. *N.Z. Soil Bureau (1954) on each site showed no Mo response in pasture These estimates are conservative, as all animals over t As proportion of 'effective' CEC (TEB) ...... ed yield. 25 kg L.W. (fat and lean) were included to give a Note: pH in water (1:2.5); cations, CEC, C, and N by standard methods (usmg arr dned s01l) descnbed by Metson (1961). Olsen Pas descnb uniform set of results, yet they clearly show the by Ministry of Agriculture and Fisheries (1979). Lime generally increased the Ca content of mixed revenue prospects of a larger weight going off to the herbage (in 94% of 90 sets), and correspondingly works. Table 2 The average profile from four sites around Te Kuiti* induced a decrease in Mg content of 65%, and in K content of 57% of the samples. These changes still left levels within the ranges considered 'normal' for p GENERAL DISCUSSION Depth pH Exch. cations (me./100 g soil) BS Ca(% c N C!N plant growth. (cm) Ca Mg K Na TEB CEC (%) ECEC) (%) (%) (Olsen) The only change of note was the Ca/P ratio which At this stage the results are incomplete. Mean 0-7.5 5.6 9.0 1.41 0.67 0.27 11.4 63.2 18 79 19.3 1.14 17 7 Was consistently increased, as shown in Table 3. If values over farms tend to hide some outstanding 7.5-15 5.6 3.4 0.4 0.19 0.10 4.2 55.9 7 82 13.2 0.76 17 2 the oft quoted ratio of 1.5, below which animal differences observed on one or two sites and obscure 15-30 5.7 2.1 0.38 0.14 0.09 2.7 50.4 5 77 8.9 0.52 17 health can decline, is any guide, the ratios found small effects on others. Nevertheless, a picture is should have little meaning except that the increases emerging of increased stock performance in line with gradual pasture improvement, an effect not *Site 5178 not included as such could still influence animal productivity. 89 88 topdressed with lime or growing near limestone In terms of the order of response obtained, the can be as responsive to lime as other soils are good. outcrops had a higher Ca/P ratio (2.1 vs 1.6). assessable in small plot mowing trials of usually short project is comparable to other grazing experiments Although the cause of the effects recorded is not yet duration. That in itself is an important finding. in the North Island, as summarised in Table 4. The The disorder was not like the 'bush sickness' of the clear, further study is obviously warranted. This effect, however, tends to overlook the comparisons are reasonable if one regards the data central volcanic plateau (starvation due to Co In looking back, it is difficult to comprehend that manner of grazing by stock which should aid pasture from locations 2, 3 and 4 as obtained at stocking deficiency), although eventually it was regarded as a a development so profitable to those pioneer improvement. Firstly, some sites developed clear rates optimal for the region, and allows for the farm possible (animal?) deficiency of Ca and P and farmers. around Mairoa, who faced near bankruptcy differences in grazing from about November through scale level of management of the trials on volcanic marginally of Co (Russell & Duncan 1956). at the time in spite of traditional fertiliser practice, to autumn, by the ewes and lambs, or even by young ash soils. On the main trial conducted by Wright and Taylor should have faded away only to see similar results re cattle where present. The control paddocks at this A full scale experiment has now been started at (1931), the increased stock thrift soon after an appear in extensive work later on. In the meantime time were markedly patch grazed, with much the Te Kuiti Research Area on a yellow-brown application of about 900 kg/ha of a lime-superphosp lime has been little used in the King Country'. pasture left to grow rank, including not only inferior loam, which will complement the regional project hate mixture (5:2) was a remarkable achievement. Clearly much scope exists to change the attitude to a species but often clumps of ryegrass and white nearing its completion. If the last site of the current However, it could have been due to a significant material of undoubted, though currently unappreci clover. By contrast, the limed paddocks were evenly work, located on a yellow-brown loam-yellow impurity of cobalt in the mixture used (a recent ated, indirect fertilising potential. and leniently to hard grazed, including inferior brown pumice soil composite, gives similar results, sample of Te Kuiti limestone had a Co level of species. Such grazing preference, confirming far the Taupo offshoot may be included, thus covering a 13 ppm and this, compared with the national mers' observations about 'improved palatability', much larger tract of volcanic ash soil than the King average of 10 ppm, is too low to support this Acknowledgments was found in four out of five sites, and also at the site Country itself. hypothesis). near Taupo. Field work of this extent cannot be done without CONCLUSION the help of the farm owners, field and laboratory Secondly, the same grazing pattern is being staff, and the local advisory officers. Their HISTORICAL recorded at the Te Kuiti Field Research Area trial The results to date may not be conclusive; contribution and that of the local lime companies is with lime on a soil of sedimentary origin. This effect, nevertheless, the prospects that volcanic ash soils much appreciated. it seems, can develop more on trials stocked at Grazing trials with lime are not new to the King optimum rather than at high or low rates when the Country. About sixty years ago farm settlers there wide difference in grazing pressure does not offer reported a nutritional disorder in sheep called the same opportunity. 'Mairoa dopiness', occurring on pastures established after clearing the forest some 15-20 years before. Thirdly, where the effect was not seen in a Phosphate fertilisers tended to increase rather than particular year, the pasture growing under cages alleviate this problem, which was accompanied by a compared with the intensity of grazing outside decline in pasture productivity. The simple experi REVIEW OF LIME RESEARCH ON TARANAKI YELLOW~BROWN LOAMS suggested less herbage being harvested by the stock ments that were then conducted apparently helped on control paddocks, or conversely, increased to restore productivity in the region (Wright & N.A. Thomson utilisation of limed pasture. Hence the co-related Taylor 1931). response of pasture and stock to lime reported in District Agricultural Scientist Table 3 has an apparent additional component of Earlier work had determined that pastures on the Taranaki Agricultural Research Station, Normanby quality even though at present its nature may not be volcanic ash soils seemed to have a satisfactory clear. nutritional status (Aston 1928), although pastures From 1935 to 1970, 45 trials investigating the SOIL SEQUENCE STUDY effects of lime on pasture growth have been recorded in Taranaki. From this large number of The responsiveness of Stratford sandy loam to Table 4 Comparison of grazing experiments with lime trials scattered over most of the soil types of the lime was investigated at five locations with different region no responses to lime were recorded. annual rainfalls, increasing from 1250 mm to Volcanic ash soils However, most of the trials were short term, of only 3000 mm over a three-year period from 1970-1974. Sedimentary soils one year duration, and assessment was on a visual basis only. Overall there was an increase in the extent (3) STRATFORD (4 Y1 av.) (1) MASTERTON (5 yr av.) pastures responded to lime as rainfall increased. Total lime 6.26 t/ha Lime 2.5 + 2.5 t/ha Local farmer interest in lime increased in the late Pastures at the two lower rainfall sites showed no pH 5.4, raised to 6.4 pH 5.5, raised to 6.0 1960s and there were many visual responses response to lime but the three higher rainfall sites D.M. B fat reported from farmers' half-paddock trials. The gave an average annual response of 10%, 7% and Ewe L.W. Wool Lamb W.W. Cows/ha E.e.!ha D.M. largest number of these were from farms situated at 13%, respectively. Responses at these sites were 3.3 +5% +6% +1% -1% +1% the higher elevations on the eastern slopes of Mt 43% greater over summer/autumn than in winter 15 +7% 4.0 +6% +6% +10% +8% +7% Egmont on Stratford and Inglewood soils. 22 +19% (inc. summer growth-extended lactation) and spring. This effect was more marked at the To re-evaluate the lime requirements of Taranaki lower two of the three responsive sites. Yellow-brown loam soils a series of trials was The soil moisture level at one of these two sites (3) TE KUITI REGION (5 sites, 2--4 yr av.) commenced in 1970 to: (2) TE KUITI RESEARCH AREA (2 yr av.) was significantly (p<0.05) increased on the limed Lime 1.25 t/ha once Lime 2.5 t/ha once plots during January and February. At the time it pH 5.6, raised to 5.9 1. determine on a rainfall sequence whether one of pH 5.5, raised to 5.7 the major soils, Stratford sandy loam, responded was fe~t that t~is observation may have been a major 14 m.a. ewes/ha 15-16 2t ewes/ha factor mfluencmg pasture responses to lime on these lamb L.W.G. +6%; wool +5% to lime, ewe L.W. +5%; wool +17% soils. lamb W.W. + 9%; wool + 11% D.M. +10% 2. evaluate the reported beneficial effects of lime D.M. increased on animal performance in a grazing trial Three rates of lime were used in this series of conducted with dairy cattle over a four-year trials: 12?0, 2500 and 5000 kg/ha applied as a single (1) Central yellow-grey earth; Kokotau si. 1.(mudstone), Bircham et al. (1970) period, and dressmg m January 1970. The highest rate gave the (2) Skeletal soil; Mahoenui si. I. (banded mud/sandstone) 3 greatest increase in pasture growth; however, 57% (3) Yellow-brown loam; various si. l. to fine sa. loams (andesite tephra) . investigate whether other soils in the higher ( 4) Yellow-brown loam; various si. I. to fine sa. loams ( andesite/rhyolite tephras) altitude areas of Taranaki were lime-responsive. of this response was obtained with the low rate, and (2, 3, 4) Edmeades et al. (1979) 90 91 the medium rate gave 80% of the total response herbage calcium levels by 25% (from 0.58 to 0. 72%) The effects on calcium and pH are summarised in CONCLUSION recorded. and decreasing the herbage magnesium levels by 5% Table 2, for the two soils derived from different (from 0.184 to 0.176%) over the late winter/spring When sampling limed soils, two factors were parent material: pH increases for the lahar-derived period. These are known factors associated with a Lime effects on soil and pasture are varied and observed: soils were 39% greater than increases due to lime on with the very applied approach taken in these trials it reduction in the availability of magnesium within the the tephras. 1. they were softer than unlimed soils ruminant animal. is difficult to isolate a single factor that could provide 2. a greater number of earthworm casts was Tahle 2 Increase in calcium and pH with the a reasonable explanation for the responses recorded. Hypomagnesaemia may have caused the depres present. cpplication of lime on the Norfolk and Inglewood However, responses did appear to be restricted to sion in milk yield recorded on the limed treatments soils (tephra soils) compared with soils formed the relatively younger soils on the eastern side of Mt The first observation was followed up with soil in August and September (Young & Rys 1977). from lahars. (Samples collected to 7.5 cm depth Egmont belonging to Inglewood, Norfolk, Stratford penetration studies which confirmed that soils which 12 months after the application of lime). and Patua series, and occurred mainly over the had been limed were easier to penetrate than summer/autumn period. Other soils m Taranaki unlimed soils. Farmers had also made this THE RESPONSIVENESS TO Lll\.ffi OF OTHER Rate of lime (kg/ha) 1250 showed little or no response to lime. observation and had reported that limed soils were SOILS AT HIGH RAINFALL IN TARANAK.I 2500 5000 more susceptible to pugging with stock and Lime had no beneficial effects on animal inaccessible by vehicles in wet weather. In light of the experience of trials 1 and 2 a series Tephra soils performance other than that which could be of nine trials was laid down encircling Mt Egmont. Calcium +1.5 +3.2 +6.1 explained by summer/autumn increases in pasture pH +0.16 Visual assessments of density of worm casts were These trials were located on the different tephras +0.29 +0.55 growth. Hypomagnesaemia increased in stock done during autumn on two of the trials grazed by Lahar soils grazing limed pasture and this caused a small and lahars at elevations and rainfalls similar to the Calcium sheep, and significant (P<0.01) increases in density +3.2 +4.8 +8.3 depression in animal performance over August and responsive sites in trial series 1 at 250-300 m pH +0.37 +0.48 +0.84 of casts were observed. elevation and 200 to 2500 mm rainfall. September. The trials were run for two years and the ANIMAL PRODUCTION ON LIMED AND responses recorded are summarised in Table 1. UNLil\.IBD PASTURES Pasture responses to lime were found to occur on the same soils which were reported by farmers around A four-year grazing trial was commenced in May the early 1970s to be lime-responsive. On these 1972 on the Stratford Demonstration Farm. The responsive soils it was again found that lime had its farm is situated on Stratford sandy loam at an greatest effect over summer/autumn, by increasing 15 elevation of 260 m and has an annual rainfall of pasture growth on average by 12 % compared with 2250 mm. Dairy cows were run in four herds on no effect over the winter/spring period. limed and unlimed pastures at two stocking rates: 3.3 and 4.0 cows/ha. Table 1 Lime responses recorded on different Over the first 12 months of the trial, 5000 kg/ha of Taranaki soils of similar elevation and rainfall lime was applied in split applications of 2500 kg/ha surrounding Mt Egmont during the first two winters, the objective being to 10 raise the soil pH above 6.0. 10 Location Soil Response to lime Significant increases (P<0.01) in pasture produc tion due to lime occurred in two of the four years Southern slopes Glenn No response and resulted over the duration of the trial in an Rowan No response average annual increase in pasture growth of 5%, or Western slopes Kahui series No response 680 kg D.M./ha. As a result of this increase in Rahotu series No response pasture growth, animal production on the limed Northern slopes New Plymouth brown loam No response treatments was 31 kg milkfat/ha higher than on the Patua coarse sandy loam Responsive unlimed treatments. This is a very good economic Eastern slopes Norfolk coarse sandy loam Responsive 5 return for the lime applied. Inglewood coarse sandy loam Responsive The four-year monthly averages of milk yield and pasture growth are summarised in Fig. 1. Pastures Molybdenum was added as a basal dressing in responded to lime during summer, autumn, and these trials and additional molybdenum and control winter, and no responses were recorded in spring. plots were included to determine the separate Animal responses in terms of daily milk yield molybdenum and lime effects. From this it was reflected this pattern of pasture response. found that sites responsive to lime were not responsive to molybdenum, and the occasional 0 Lime was found to cause a significant (P<0.05) molybdenum responses occurred in the spring, while deterioration in stock health, especially in the the lime responses were during summer and autumn. incidence of hypomagnesaemia and chronic disor Additional to these trials a lime and molybdenum ders resulting from magnesium deficiency. During trial was conducted concurrently at the Stratford Month the three three years of the trial, 36 cases of clinical Demonstration Farm. Lime responses were again grass staggers were recorded on the limed recorded but there was no response to molybdenum. Milk y:i.eld .. treatments and only 17 on the non-limed. Blood Lime lfo Li.rnG sampling of cows in spring of the second and third Soil test (quick test) results of samples taken two 5 years of the trial showed that lime caused a years after the application of lime showed a marked % Increase in pasture growth d.ue to Lime significant (P<0.01) depression in blood magnesium increase in the calcium and pH levels but there was levels. This has been attributed to lime raising the no effect on phosphate, potassium or magnesium. Figure 1 The effect of lime on the average daily milk yield and pasture growth 92 93 POTASH REQUIREMENTS OF THE SANDY LOAM AS AFFECTED BY determined. During the study period the trials amounts of K Gl.pplied as fertiliser potash were taken remained closed from stock, three consecutive up by the pasture at each of the three sites. Rainfall pasture cuts were taken, and at each cut all clippings had no effect on K uptake of applied fertiliser, were removed. although there was a rainfall difference in the N .A. Thomson The results of this study (Fig. 1), show a very amount of applied K remaining in the top 40 cm of District Agricultural Scientist similar trend as observed in the earlier study of soil soil. It is concluded that the greater amount of K Tar1maki Agricultural Research Station, Normanby test results. This leads to the conclusion that at the unaccounted for at the high rainfall sites must have higher rainfall sites there is a greater proportion of been rapidly lost from the soil through leaching. applied K which cannot be accounted for by either The response of pasture to the application of low level of non-exchangeable K, a property At the low and high rainfall sites (Table 1) similar uptake into pasture or by the soil to a depth of 40 cm potassium fertiliser was studied in a rainfall common to volcanic ash soils high in allophane. amounts of fertiliser potash had been used for the three months after application. Very similar sequence on Stratford sandy loam over a three-year three years prior to commencing the trial and for the period. Five sites were selected at locations of 1250 mm Rain!aU. increasing rainfall, from 1250 mm to 3000 mm on, PASTURE RESPONSES ~?OOO rum Ra.inf all 3000 rr;m Rainfan the rising southern and eastern slopes of Mt Egmont, and at each site four rates: 0, 125, 250 and Results from 12-15 pasture cuts taken seasonally 160 500 kg of KCl/ha were applied annually as a split over three years showed inconsistent trends in dressing in April and August. However, for this potash responses at the different rainfall sites. The article, only two rates (0 and 250 kg KCl/ha) have highest response was recorded at the 3000 mm been used to compare the responsiveness of sites. rainfall site with the next most responsive site being at 1625 mm rainfall. The other three sites responded The trials were run over three years, from 1970 to to potash to a similar degree. All sites responded to 1973, and operated on an occasional cut basis, with potash more during winter and spring (7% increase harvests taken seasonally. This was done to avoid in pasture growth) than during the summer/autumn potash imbalances created by continual removal of period (only a 2% increase in pasture growth). 120 clippings, but the trials were subjected to the transfer of potash between plots by the grazing Potash responses expressed in terms of D.M. <-JeiJ animals. Neither problem could have been com yields did not appear to reflect the true responsive ., '15 100 pletely avoided without operating a full scale grazing ness of each of the sites. Pastures at the three higher ~··" trial, and the information gained from this trial could rainfall sites were predominantly browntop, Agrostis "' not be used in any way to give absolute potash tenuis, with a very low content of white clover. Over ~ !,..{ recommendations for each location. Principles only the summer/autumn period marked increases in 0 could be determined from such a trial design. clover vigour were observed on the potash plots, but +:' Bo this was not expressed as an increase in D.M. yield. § Quick test K levels collected from each site prior Botanical composition of pasture from selected 0 to laying down the trial declined from 13 to 6 as tl harvests showed an increase in white clover content d rainfall increased but this did not reflect the level of (:,() and a decrease in grasses. The depression in the r{ maintenance fertiliser previously applied. These c1 proportion of the other grass components (predo ·I" results are summarised in Table 1. Type of farming minantly browntop) was greater than that recorded () 8 appeared to be the major influence on soil potash for ryegrass. levels. On the two sheep/beef units, soil potash l+O levels per unit of applied potash were higher than on The effect of potash on pasture composition and the dairy farms. Under dairying, potash soil test the problem of potash transference by grazing values declined as rainfall increased, a factor which animals could have resulted in D.M. yield not giving did not appear to be associated with previous potash a true reflection of the total responsiveness of each usage. of the sites to potash. Potassium fixation in the top 15 cm of soil was low; associated with this low potassium fixation is a EFFECT OF APPLIED POTASH ON SOIL TEST 0 Soil samples were collected at increasing depths: Table 1 Description of the five sites selected for 0-2.5 cm, 2.5-7.5 cm, and 7.5-15 cm, in August the rainfall sequence study of Stratford sandy 1971 to determine the residual effect of autumn loam applied potash at three sites. From these results it was noted that a greater amount of the potassium l:'J10U:')1: of K a.pp!fod Total K a;t Total K (K) applied as fertiliser potash remained in the soil Rainfall Farming Annual application K soil test :Jta.rt ~ c:-<.ecountod at the lower rainfall site than at the two higher of ~ (mm) system of KCI (kg/ha)* at laying down g in coil befo:ra ' fO:L' nf.. 1:,cr rainfall sites. study coil ~ pi:;t~sl1 j Elf:mt.hs u.ppHsd. 3 1250 Dairying 225 12.7 In spring 1973 a more intensive investigation of 1625 Dairying 230 9.6 this aspect was made at the low, medium and high ' 2000 Sheep/beef 112 7.0 rainfall sites over a three-month period following the 2250 Sheep/beef 95 9.1 K mIB.ccountied fox: 3000 Dairying 200 5.6 application of potash. Through the measurement of K uptake in herbage and K in the soil to a depth of afte:i::- 3 recrrt.1.1;1 . •Average potash application of the previous three years before 40 cm before, and three months after, potash laying down the trial application, a budget for K at each site could be Figure 1 Gains and losses of potash over a three-month period in spring 94 95 three-year duration of the trial, but soil K levels Stratford sandy loam. The requirements increase at remained low at the high rainfall site. From the data least three-fold with an increase in annual rainfall used in Fig. 1, it can be calculated that at the low from 1250 mm to 3000 mm. High rates of rainfall site only 14% of the K applied as fertiliser application as single dressings would be wasted and was lost over three months, while at the high rainfall the higher requirement for K should be satisfied site for the same period 70% was lost. This suggests through an increase in the number of times potash is HORTICULTURE ON WAIKATO YELLOW~BROWN LOAMS a very much higher requirement of soils at the higher applied each year, applying no more than 125 kg/ha of muriate of potash at any single application. rainfall sites for potassium fertilisers. E.E. Toleman, Ministry of Agri~ulture & Fisheries, Hamilton One major failure in this series of trials was that To meet the pasture requirements for potash fully rainfall was not recorded, and it is strongly under intensive dairying, it is recommended from these results for localities on Stratford sandy loam Since its early development, land used for gently undulating. There can be soil drainage recommended that any future trial work in Taranaki agriculture in the Waikato area has been devoted with potash be supported with rainfall data collected above 2250 mm rainfall that muriate of potash at pr?blems, but so long as there is an adequate outlet largely to pastoral farming, and horticulture has this ea~ be rec~ified in most cases. Most tend to dry on the site. about 125 kg/ha be applied in August, November and March each year. The requirement for the occupied only a very small part of the total area. out fairly quickly, and irrigation is needed to autumn application will be very much dependent on While a fairly wide range of crops has been grown, maintain maximum plant growth. Poor drainage in PRACTICAL RECOMMENDATIONS summer rainfall and in a dry year may not be these have been, with very few exceptions, almost parts can aggravate associated problems of root necessary. At low rainfall localities one application entirely for local consumption. Consequently, areas diseases, especially where deep rooting plants such Although not fully supported by pasture yield in spring will be all that is necessary, but following a of horticultural production have been few and as fruit trees are involved. With frequent cultivation, data, it is concluded that rainfall would have a very wet summer there may be a requirement for a located mainly around urban areas. Soil type is not as on market gardens, the soil structure can marked effect on the potash requirements of further application of potash in autumn. be major factor in the selection of these areas and it deteriorate quickly and plant nutrient problems soon is largely coincidental that much of this production is arise. Wh~re the land is flat or gently undulating, located on yellow-brown loams. Where soil type was water erosion can occur, and on steeper gradients actually a major factor in the selection of an area of can be so serious as to require grassing down under horticultural cropping this group of soils was often crops such as orchard trees. Wind erosion is chosen. generally negligible. However, with good soil Apart from a limited amount of pipfruit, and management, such problems can be overcome, and grapes processed for wine, there has been until very these soils are then capable of carrying good recently little movement of horticultural produce out horticultural crops. of the Waikato. To discuss the historic use of these Waikato Since 1978 there has been much interest shown by yellow-brown loams for horticulture can be mislead farmers in diversification into horticultural cropping. ing. Such a relatively small total area has been used The reasons for this are many, but with continually for this purpose in the past that it is more instructive rising costs many farms used solely for cattle or to consider their potential in regard to the expansion sheep are becoming uneconomic. Hence, because of horticultural production which seems likely in the the farmer already has the land, he tends to use it Waikato. There are currently many factors pointing even if it is not entirely suited to horticulture. to a substantial increase in horticultural activities in However, there are increasingly more cases where the agricultural economy of the Waikato. The the entire farm is turned over to horticultural extensive areas of organic soils will undoubtedly be production. In such cases crops may be, but are not developed for this, as will the mineral soils. always, chosen in relation to the soil types and other However, if soil type is the prime factor in the factors. Should these farms be on the better types of selection of land for most crops, then the greater yellow-brown loams and with other factors satisfac development should be on the yellow-brown loams tory, then they normally command a higher price wh~re these are sufficiently deep and adequately than if on any of the other Waikato soil types. In the dramed. There are indications that considerable all too few cases where potential growers choose expansion will take place in areas of certain crops land for specific crops then the better yellow-brown including berryfruit and asparagus. Other vegetables loams are generally the first choice. will probably be limited by the absence of local processing facilities, but if these were to become Much of the farm land which has been subdivided available substantial amounts of land would be into 4-ha blocks comprises yellow-brown loams. needed for the specific crops to be processed. No Within a short distance of Hamilton, for example, major expansion of the production of pip and stone there are about 1000 such holdings on these soils. fruit appears likely at present, although there is considerable interest in feijoas. Many of these are near Hamilton, Ohaupo, Cambridge and Matangi and this, in fact, forms the Horticultural statistics are not collected with largest cohesive area of yellow-brown loams in the reference to the crops grown on the different soil Waikato. They belong to the Horotiu suite and are types, but it is estimated that about 70% of the mostly Horotiu sandy loam (48a) and Horotiu-Te present production would be on the various yellow Kowhai complex soils ( 48b). There is considerable br?wn loams. For the reasons already mentioned, variation, but they are generally fairly easy to work, this figure could well become lower as horticultural mostly of medium or low fertility and either flat or production increases on other soil groups. 96 97 LAND USE LAND USE CAPABILITY OF YELLOW-BROWN LOAMS J.R. Fletcher and M.R. Jessen Aokautere Science Centre, Ministry of Works & Development, Paimerston North INTRODUCTION limitation to agricultural use is climate. For example, on the Taranaki ring plain where yellow Yellow-brown loans, with their excellent physical brown loams have developed from andesitic tephra, properties, are one of the most versatile soil groups the main limiting factor is rainfall. Rainfall varies for cropping, pastoral and forestry uses in New from approximately 1200 mm/year near Hawera, to Zealand. A detailed assessment of the land use an estimated 8000 mm/year on the higher slopes of 9. Sou capability of yellow-brown loams is provided by the Mt Egmont (2518 m a.s.l.). Within this rainfall New Zealand Land Resource Survey (NWASCO range temperatures are mild, although forests 1975-1979). become more frequent inland and with increasing elevation. Cropping versatility decreases with An assumption in this survey is that no one increasing rainfall and this results in progressively physical factor can be used as the basis for less versatile land use capability units. The effect of agricultural or forestry planning: rock type, soil, rainfall on land use capability is illustrated in Table 1 slope, erosion, vegetation and climate are all in which slope, parent material (all tephras giving important to varying extents. The land use capability yellow-brown loams), erosion type and degree, and method of land appraisal uses the homogeneous unit vegetation are constant while rainfall is the principal area approach to mapping which enables all five climatic variable. There is a similar sequence of land physical factors to be integrated. It allows different use capability units with decreasing versatility as the Land usci capabili factors to dominate in capability assessment as elevation and rainfall increase from south of considered appropriate. The result is a broadly Ohakune north to Pokaka. Slopes are flat to uni~s wirh ycillow based assessment of the physical capability of land undulating with Ohakune soils developed from for permanent sustained production. The land use Tongariro tephras giving units Ilcl, Illcl and IV cl loam soils. capability classification is briefly described in (Taranaki-Manawatu regional extended legend). Appendix 1. A more detailed description is given in Potatoes, root and green fodder crops, root and the Land Use Capability Survey Handbook (Soil brassica vegetable crops grow well in all of these Conservation and Rivers Control Council 1971). units; however, wheat and barley cereal crops grow In the New Zealand Land Resource Survey the well only on unit Ilcl ( <450 m a.s.l.; rainfall South Island was mapped as one region while the 1400 mm approx.) and are marginal on unit Illcl North Island was divided into ten regions, each with (450-700 m a.s.l.; rainfall 1400-1800 mm). its own capability classification described by an extended legend. In Fig. 1 the North Island regional Soils boundaries have been superimposed on a map Soil limitations become dominant only where showing the distribution of yellow-brown loams as yellow-brown loams have shallow soil profiles (e.g. identified on the Land Resource Inventory Work less than 30 cm deep), are stony or contain sheets. significant rock outcrops. Some yellow-brown loams The Land Use Capability system identifies four have less suitable physical characteristics for dominant limiting factors in land use capability cultivation than normally expected; for example, in erosion, wetness, soils and climate. In this paper the Franklin County the Karaka soils (derived from extent to which these limitations apply to units with water-sorted tephra) are better suited to permanent yellow-brown loam soils in the North Island is crops because of their rapid structural breakdown discussed, using examples from Taranaki, Ohakune, under cultivation. Waikato and Bay of Plenty. This will be followed by Soil limitations are well illustrated in western a summary of production potentials for land use Taranaki where the Opua lahar Formation (c. 7000 capability units with yellow-brown loam soils. years B.P., Neall 1976) was deposited after the principal soil-forming airfall tephras. The yellow brown loams formed on these lahars are shallow LAND USE CAPABILITY LI1\1ITA TIONS ON (<30 cm and often <15 cm deep), bouldery, and YELLOW-BROWN LOAMS occur on a hummocky boulder-strewn terrain. On 4 OOO OOO older lahar formations (Warea, c. 14 OOO years B.P.; Climate Pungarehu, c. 25 OOO years B.P., Neall 1976), Oakura and Okato Tephras provide a mantle of On flat and gently undulating slopes, with deep deep tephra to allow the soils to develop with fewer Figure 1 Distribution of land use capability units with yellow-brown loam soils. Location of regional boundaries used in the New Zealand well drained yellow-brown loams, the dominant limitations. Table 2 summarises the relationship Land Resource Inventory Survey. 98 99 .ts on yel.low-brown loams in Taranaki in which climate is the gleyed i~ ~ow-lying depressions or where subsoil capability units. These data have been collected in Table 1 Sequence of land use capability Unl drainage is impeded by a compact layer. An example conjunction with Ministry of Agriculture and dominant limitation of this occurs in South Taranaki where Egmont Fisheries advisory officers and foresters from the black and brown loams, strongly mottled subsoil New Zealand Forest Service. Cropping use Typical locality phases, occupy low lying depressions and are Rainfall (mm) Typical soil Other physical Typically, potentials for grazing and exotic L.U.C. Unit description developed from Taranaki tephras over compact (approx.) mapping wrlts features forestry on land use capability units with yellow unit Jaharic breccias (unit IIw3, Taranaki-Manawatu brown loams are high and very high respectively (see Oakura Urenui New Plymouth black Subtropicai fruit; citrus . regional extended legend). Icl Flat to undulating <1600 fruit; pip fruit; berry fruit; Table 3 and Appendices 2 and 3). Table 3 records loam coastal terraces in nurseries; vegetables; present and potential stock capacities, as well as north Taranaki with Egmont black loam Erosion New Plymouth brown potatoes; cereals; solanum; fertiliser requirements for the maintenance of these yellow-brown loams root and green fodder crops Erosion of yellow-brown loams is generally not as carrying capacities, for land use capability units with developed on loam serious as in the geographically associated zonal yellow-brown loams from the Bay of Plenty andesitic tephra Hawera, Norrnanby, Egmont brown loam Exposed to Subtropical fruit; citrus yellow-brown earths. The Erosion Map of New Vokanic Plateau regional extended legend. Table 3 Ic3 Flat to undulating <1200 Okaiawa predominant fruit; berry fruit; nurseries; Zealand (NWASCO 1974*) shows areas of yellow also records the physical potential for exotic forest slopes in south S.W. winds vegetables; potatoes; Taranaki with cereals; root and green brown loams as having an insignificant erosion growth, expressed as Site Index for P. radiata. yellow-brown loams fodder crops potential on flat to strongly rolling slopes under Grazing potentials given in Table 3 are very high developed on pasture and only a slight erosion severity for hill andesitic tephra for unit IIel, high for units IIIel and IVel and Shelter belts Berry fruit; nurseries; Within country under pasture. Under cropping, potential Flat to undulating <1400 Egmont black loam approximately 5 km moderately high for units Viel and VIe2. The lower Hc2 required to vegetables; potatoes; erosion severities vary from slight on He's to severe slopes with minimise effect cereals; root and green of the south and potentials for the Vie units are probably the result of yellow-brown loams on IVe's: erosion forms are mainly sheet, rill and of salt spray on fodder crops west Taranaki coast poorer pasture vigour caused by the increasing occurring within wind. On cooler high country plateau environments crops effects of aspect, exposure and nutrient losses to 5 km of the south north-east of Taihape (elevation between 500 and runoff, as slope angle increases. Taranaki coast and 1100 m), Moawhango and Titapu soils have a exposed to salt burn Kaponga, Eltham Egmont brown loam increasing Berry fruit; nurseries; potential for wind and sheet erosion and also soil slip Provided that the tephra is sufficiently deep IIc3 Flat to undulating 1200-2000 vegetables; potatoes; slopes with New Plymouth brown erosion (where slopes exceed 21°). The erosion (greater than approximately 1 m) and reasonably loam altitude, cereals; root and green yellow-brown loams fodder crops severities depend on slope angle, aspect, elevation well drained, and the climate is suitable, yellow in Taranaki where New Plymouth sandy and management. Here, once the soil surface is brown loams provide an excellent medium for P. loam cooler rainfall is bared, the erosion hazard is accentuated by frost radiata establishment and growth. Good root 1200-2000 mm/year New Plymouth black loam winter heave. Similarly, a severe wind and sheet erosion aeration within the subsoils largely accounts for this. Stratford sandy loam potential occurs on the shallow and stony 'yellow In Table 3, exotic forest growth potentials are all Stratford loam temperatures, brown loams' on moraines and outwash gravels of very high with little difference between the units. shorter Stratford, inland Southland. The small variation reflects the general view that New Plymouth brown Berryfruit (brambles only); Ulc4 Flat to undulating 2000-2500 vegetables (brassicas and Inglewood growth of P. radiata is not greatly affected by slope loam Erosion forms found on hill country with yellow slopes with growing root crops only); potatoes; angle unless slopes become very steep. The Stratford fine sandy brown loams are soil slip, minor earthslip and sheet. yellow-brown loams root and green fodder crops important factors that influence rates of P. radiata in Taranaki where loam season In those hill country units where the tephras are Patua sandy loam and growth are depth and drainage of the soils and rainfall is greater than approximately 1 m deep the influence 2000-2500 mm/year loam climate: these factors are relatively constant for the Inglewood coarse sandy of the underlying lithology on erosion is usually land use capability units shown in this table. loam negligible. An example, however, of the underlying Lowgarth sandy loam lithology over-riding the influence of the tephra Root and green fodder Within (approx.) It is evident that there is a wide difference 2500-3500 Patua sandy loam and Ivc3 Flat to undulating crops 4 km of Egmont cover is found in the Te Kuiti-Aria area where between present average and potential carrying slopes in Taranaki loam National Park Oparue silt loam and clay loam hill soils cover Inglewood coarse sandy capacities. In fact the inventories, stock carrying with yellow-brown boundary jointed mudstones and siltstones of the lower capabilities and site indices all show that North loam soils. High loam rainfall Lowgarth sandy loam Mahoenui Formation. In many of these localities the Island land use capability units with yellow-brown (>2500 mm/year) Rowan coarse sandy long history of deep earthflow and gully erosion has loams are capable of significantly higher produc and cool winter loam removed the tephra cover, resulting in a mosaic of tivities for both pastoral and forestry production temperatures finer textured yellow-brown earth soils on the flow than is presently achieved. It is suggested that from severely limit areas and yellow-brown loams on the stable areas cropping use the data presented in this paper, the present between flows. Unit VIe9 (Waikato regional limitations to increased production are not physical. extended legend) is mapped in this situation where If inputs to increase pastoral productivity were between land use capability units and dep!h ~f the main limitation to sustained safe land use is deep directed to units with yellow-brown loam soils, Table 2 Relationship of land use capability to the tephra on these lahars. The shallow soils occurring in seated earthflow and gully erosion. returns on investment in most instances would be depth of tephra on lahars in Taranaki considerably greater than equivalent investment on VIs3 preclude cultivation. for pasture rene"".al a;~ Terracette creep is evident on most slopes greater restrict pasture production. In Vsl, soils marginal land. · · f asture than 21-23°. This erosion form usually has little sufficiently deep to allow cuI t1vatl~:m or P .s- irnpact on land use because of the slow rate of Land use Depth of tephra renewal and soils have better physical characten capability Slope Typical lahar formation ' ·11· · · nd the deformation. However, sloughing off the terracette unit ties. Unit Vcl has virtually no s01 im1tat1ons a and crests, often caused by cattle trampling, can lead to only factors preventing cropping use are slope soil loss. APPENDIX 1 LAND USE CAPABILITY >lm Vcl 21-25° Pungarehu Formation climate. CLASSIFICATION Vsl 16-25° Warea Formation 30 cm-1 m Opua Formation <30cm Vls3 16-25° Wetness PRODUCTION POTENTIALS ON YELLOW The Land Resource Inventory worksheets contain Soil wetness is not usually an important factor in BROWN LOAMS two sets of land resource information: a land the land use capability of yellow-brown loamsd resource inventory and a land use capability .Agricultural production and exotic forestry Locally, however, subsoils may become mottled an assessment. Potentials have been collected for all land use 100 101 Land Resource Inventory of crops, pasture or forest species and have about Table 3 Stock and forestry data for land use capability units with yellow-brown loam soils in the Bay of Plenty Five key physical land inventory parameters are the same potential yield. recorded using the unit area approach to mapping. Capability units are arranged in order of L.U.C. Unit description Slope Typical soil Carrying capacity Pasture fertiliser requirements-sheep & cattle These are: rock type, soil, slope, erosion and decreasing versatility and increasing limitation to unit mapping units (SU/ha)* Initial Maintenance Trace growth vegetation. use, e.g. VIIe5 has a higher capability than VIIe8 present* attainable present average attainable phys. elements (S.I. but not as high as VIIe2. Capability units are specific average phys. pot. grazing capacity pot. grazing P. A series of mapping units are thus delineated which are physically homogeneous within the to a region and do not correlate between regions. IIel Flat to gently 0-30 Katikati black 17 26 l250 kg/ha 350 kg/ha 400 kg/ha cobalt 40-41 limitations of the 1:63 360 scale: where any factor changes significantly a boundary is drawn and a new undulating terraces near sandy loam cobaltised superphosphate superphosphate copper APPENDIX 2 DEFINITIONS OF sea level. Soils are free superphosphate 150 kg/ha 200 kg/ha mapping unit created. Using the above inventory STOCK FIGURES draining, fertile muriate of muriateof parameters, and other relevant physical information yellow-brown loams. potash potash such as climate, each mapping unit is given an The unit has a Present Ave.rage-The number of stock units per assessment of its land use capability, i.e. its capacity moderately high hectare (SU/ha) which the 'average farmer' is versatility and is for permanent sustained production. especially suited to typically carrying on a particular land use capability unit. citrus and subtropical Land Use Capability fruit orcharding. There Attainable physical potential-The number of SU/ha is a potential for slight The Land Use Capability classification has 3 wind and rill erosion components. capable of being carried on a particular land use when cultivated. capability unit, assessed within the limits of present Hlel Undulating to gently 4-7° Katikati sandy 15 23 1250 kg/ha 300 kg/ha 350 kg/ha cobalt 38-41 Class: The land use capability class (represented technology and given favourable socio-economic rolling slopes near sea a few loam cobaltised superphosphate superphosphate by a Roman numeral) expresses the total degree of conditions. level with free-draining, short Katikati black superphosphate 130 kg/ha 150 kg/ha limitation in eight degrees of decreasing versatility. fertile yellow-brown slopes sandy loam muriate of muriate of Classes I-IV are suitable for cropping, pasture or Stock carrying capacities (SU/ha) are ranked into loams. There is a 8-15° Whakamarama potash potash the following categories. potential for slight to sandy loam forestry while classes V-VII are limited to pastoral moderate wind, rill and or forestry use. The limitations reach a maximum Production po1te1rnt1:a1 Stock units/hectare sheet erosion when with class VIII land which is not suitable for grazing cultivated. or production forestry. very high >25 IVel Rolling to strongly 8-15° Katikati sandy 15 23 1250 kg/ha 300 kg/ha 350 kg/ha cobalt 35-41 high 21-25 rolling slopes near sea a few loam cobaltised superphosphate superphosphate Subclass: The land use capability subclass (iden moderately high 16-20 level with free-draining, short Katikati black superphosphate 130 kg/ha 120 kg/ha tified by a lower case letter in the land use capability medium 11-15 fertile yellow-brown slopes sandy loam muriate of muriateof code) divides the land within each class according to low 6-10 loams. There is a 16-20°Waitekauri potash potash the major kind of limitation to use. potential for moderate sandy loam very low 1-5 to severe sheet and rill Te Manaia sandy The four subclasses are: sparse <1 erosion when loam cultivated. e erodibility: where susceptibility to erosion is the dominant limitation to use Vcl Strongly rolling slopes 16-20°Katikati sandy 13 20 1250 kg/ha 350 kg/ha 350 kg/ha cobalt 37-39 APPENDIX 3 RANKING OF EXOTIC FOREST near sea level with loam, hill soil cobaltised superphosphate superphosphate w wetness: where a high water table, slow GROWTH POTENTIALS free-draining, fertile Whakamarama superphosphate 100 kg/ha 120 kg/ha internal drainage and/or flooding constitutes the yellow-brown loams sandy loam, hill muriate of muriate of major limitation to use formed from soil potash potash moderately weathered s soil: where the major restriction to use is a Exotic forest growth Site Index (the expected tephras over stable rock limitation within the rooting zone. This can be in metres of P. types. due to a shallow soil profile, stoniness, rock radiata trees at a Vlel Moderately steep to 21-25°Katikati sandy 13 20 1250 kg/ha 300 kg/ha 350 kg/ha cobalt 35-41 outcrops, low moisture holding capacity, low particular site at age 20 steep hills near sea level loam, hill soil cobaltised superphosphate superphosphate fertility where this is difficult to correct, salinity years) with yellow-brown loam Waitekauri superphosphate 100 kg/ha 120 kg/ha or toxicity. soils formed from sandy loam, hill muriateof muriateof moderately weathered soil potash potash c climate: where the climate is the major very high >35 tephras over stable Whakamarama limitation to use. volcanic rock types. sandy loam, hill high 30-35 There is a potential for soil Unit: The land use capability unit (represented by medium 25-29 moderate soil slip Te Manaia sandy an arabic number) groups together those inventory erosion. loam low 20-24 units which require the same kind of management, very low <20 VIe2 Strongly rolling to 21-25°Katikati sandy 13 20 1250 kg/ha 300 kg/ha 350 kg/ha cobalt 35-41 the same kind and intensity of conservation moderately steep hills loam, hill soil cobaltised superphosphate superphosphate near sea level with Waitekauri superphosphate 100 kg/ha 120 kg/ha treatment and are capable of growing the same kind yellow-brown loam soils sandy loam, hill muriate of muriate of formed from soil potash potash moderately weathered Whakamarama tephras over sandy loam, hill unconsolidated rock soil types. There is a Te Manaia sandy potential for moderate loam soil slip and gully erosion. *For definition see Appendix 2 tFor definition see Appendix 3 102 103 YELLOW-BROWN LOAMS AND FORESTRY RECONTOURING OF YELLOW-BROWN LOAMS IN THE PUKE G.M. Will, Forest Research Institute, Rotorua W.E. Cotching, Soil Bureau, Rotorua New Zealand's exotic forests have been mainly land clearing and conversion to pasture. If these soils The demand for suitable land for growing the topsoil, any wholesale disruption of this subsoil planted on soils which were considered unsuitable were now reafforested, e.g. with radiata pine, fast subtropical and citrus fruits in the Bay of Plenty has will impair its good physical properties. Below these for agriculture or other uses. Typical examples are growth rates could be expected. Features favouring increased, and property prices are rising due to the ash beds occurs an older 3- to 4-m thick layer of the coastal sand forests in the Manawatu, Auckland tree growth are good moisture retention capacity high profitability of this fruit production., so much deeply weathered volcanic ash (Maketu Tephra and North Auckland regions, and forests on stony combined with a deep friable soil in which tree roots so that some landowners feel that they cannot afford Formation) which, due to its heavier texture, does soils in Canterbury, gumland soils in North can exploit a large soil volume. In addition their to leave any part of their land idle. not have the good soil physical properties of the Auckland and pakihi soils in Westland. The large nutrient status is at least moderate with no The area around Te Puke which is suitable for overlying younger ashes. and very productive forests on yellow-brown pumice deficiencies likely to affect tree growth. subtropical and citrus fruit production consists of soils may never have been established if there had' Following recontouring, the topsoil is placed back It is of interest to note that some of the most yellow-brown loam soils on large, deeply dissected on the remodelled land surface. In the gullies, this been earlier identification of the role of cobalt terraces. Although these terraces have a predomin deficiency in bush sickness. productive forests on yellow-brown pumice soils are means that there is now up to 6 m of soil with those where the tree roots have access to paleosols antly smooth contour they also have a considerable desirable characteristics for plant growth, but on the In contrast, the yellow-brown loams are relatively which are, in fact, 'buried yellow-brown loams'. number of smaller deep-sided gullies on them. It is terrace tops and sides there is now a 10- to 20-cm fertile soils which have been keenly sought after for There is, then, every reason to conclude that, as a these 2- to 10-m deep, smaller gullies which are topsoil layer directly overlying the Maketu Tephra agriculture and more intensive forms of land use. As group, yellow-brown loams are soils on which very increasingly being recontoured or 'smoothed out' Formation which is a much less beneficial medium a result there have been no large scale exotic forest productive forests could be established. However, with the use of heavy earthmoving machinery. for plant growth. It has been observed that plants plantations established on these soils. However, this looking to the future, it seems highly likely that they The landowners conducting these recontouring growing in this upper position of recontoured land is not to say that they are unsuitable for forestry-if will continue to be used for the more site-demanding operations seem to have the mistaken notion that are not nearly as healthy as those in the gullies. If anything the reverse is true, as many fine stands of types of vegetation associated with agriculture and soil consists merely of the black topsoil. This top 10- landowners insist on recontouring these small gullies native forest grew on yellow-brown loams prior to horticulture. 20 cm of soil is stripped off the land and stockpiled then they should perhaps do so by moving this until being replaced at the end of operations. In deeper Maketu Tephra and replace both the removing the topsoil with heavy machinery the soil overlying younger ashes and the topsoil. However, the cost of such an operation is bound to be LAND USE ON THE YELLOW-BROWN LOAMS IN THE TAURANGA-TE PUKE structure must be drastically altered. Thus, when this topsoil is replaced its aeration, drainage, and prohibitive. DISTRICT water holding properties are probably considerably Another problem arising during these contouring reduced. Overseas experience has shown that a operations is that of soil erosion. If heavy rain occurs W.E. Cotching, Soil Bureau, D.S.I.R., Rotorua minimum of five years under grass is required to while the soil is stripped bare, considerable volumes restore the soil physical properties to their original of soil are liable to move down the gullies to clog up state after a period of intensive cultivation. Soil pipes and drains and even, in some cases, to be The two soil series of yellow-brown loams in the horticulture has been a dramatic rise in land values. changes occurring during recontouring are probably deposited over neighbouring properties. For future Tauranga-Te Puke area are Katikati sandy loam and This has resulted in the thinking by some landowners similar to those occurring due to cultivation. Thus, a contouring operations, it is advised that some form Te Puke (provisional name) sandy loam. that all available land should be put into similar period of structural improvement under grass of soil-retaining weir be placed at the downstream would be required for restoration of soil structural Land use on these yellow-brown loams in the Bay horticultural production. In order to do this many end of these gullies to prevent such soil loss. recontouring operations have been carried out. properties following recontouring. of Plenty has for many years been pastorally based Although this practice is financially sound at On the surface then, recontouring may appear to with dairying being one of the main farming During recontouring, the 2- to 3-m thick layer of present, the wisdom of such action is questionable be a worthwhile and sound practice but on deeper practices. Sheep and beef breeding and fattening dark yellowish brown soil below the black topsoil is when considering possible changes in the inherently consideration the benefits may not be sufficient to have also played their part. stripped off the terrace tops and dumped into the offset the disadvantages of the resulting disturbed good physical properties of yellow-brown loams (see gullies. This 2-3 m of subsoil consists of volcanic The beneficial climate, potentially highly produc Catching, following article this volume). soil profiles, poorer physical characteristics and ashes ranging from 7000 to 14 OOO years old and it possible soil erosion. Nature has taken many tive yellow-brown loam soils, and attractive financial gives the soils of the Te Puke district the bulk of the returns, have all meant that horticulture is now Although horticulture has been in the limelight in thousands of years to form these soils, and man the Bay of Plenty over the last few years, farmers on very desirable soil properties of free drainage and should perhaps modify his land use to the existing becoming the predominant industry in the Bay of yellow-brown loam soils which are not ideally suited high water holding capacity, which are a require Plenty. The various horticultural crops being grown soil rather than recontour the land to suit his present to horticulture, for reasons such as elevation or ment for subtropical and citrus fruit growth. As with uses. in this area include citrus and subtropical fruits (e.g. tangelos, lemons, kiwifruit, tamarillos, and slope, are well aware of alternative land uses. avocados), pip fruits (e.g. apples and pears), stone Alternatives which are now being considered and fruits (e.g. peaches), and berry fruits (e.g. undertaken include deer and goat farming. Other land uses which have been adopted include boysenberries and blackberries). vegetable production for the local market, and Plantings of horticultural crops started in the Bay maize cropping in some localities. of Plenty early this century, but the lack of marketing facilities probably accounted for the The land use potential of yellow-brown loams in limited areas planted. With the realisation of the the Bay of Plenty is now being realised, with potential, and later establishment of marketing research organisations and farmers continually avenues for horticultural exports, there has been a looking at alternative, highly productive and dramatic increase in horticultural plantings over the intensive land uses. The D.S.I.R. research orchard past 20 years, with current planting rates of kiwifruit at Te Puke is conducting extensive trials on various alone amounting to approximately 400 ha/year. citrus, subtropical and stone fruits, while frequent field days and seminars are providing information Concomitant with the high financial returns from and ideas to the district's farmers. 105 104 two orders of magnitude higher than 'normal' Phosphate retention data showed that the topsoil 12. WATER QUALITY rnaintenance fertiliser dressings. is saturated with phosphate, and little or no sorption occurred following phosphate addition. ANALYSIS OF SOIL PROPERTIES Inorganic nitrogen analyses, using steam distilla SPRAy IRRIGATION OF DAIRY FACTORY WASTEWATER ON A KOPUA SILT tion (Bremner & Keeney 1964) were made to a LOAM In order to determine what soil property changes depth of 600 mm. As with the inorganic phosphate, had been induced by 15 years of waste application, a soil nitrate levels were found to be substantially comparative study was made between selected higher at the disposal site (Table 3). This held true K.W. McAuliffe parameters at the disposal site and at a neighbouring for all depths examined, although the largest Department of Soil Science, Massey University, Palmenton North non-irrigated or control site. The soil properties differences occurred in the surface 200 mm. looked at were: infiltration rate, saturated hydraulic Ammonium levels did not exhibit such a marked conductivity (k), bulk density, pH, inorganic change as nitrate, although up to three-fold nitrogen and phosphate, mineralisable nitrogen, differences were recorded between the two sites. SITE DESCRIPTION total nitrogen, organic matter, soil respiration and INTRODUCTION earthworm numbers. Potentially mineralisable nitrogen levels (deter mined by incubating soil at 25°C for 14 days) differed Historically, a common method of dairy factory Tue disposal farm lies on an alluvial plain to the Field studies showed that for most of the time markedly between the two sites. The mineralisable wastewater disposal has been by discharge to open eastern side of the Ruahine Range. The soil type is infiltration rates at the disposal site and at the nitrogen content in the surface layer of the disposal waterways. However, primarily as a r~sult_ of Kopua silt loam, a composite yellow-brown loam control site were similar, averaging around 3000 mm site was found to be approximately four times growing public awareness of water cont3mmat10n, formed from mixed andesitic ash and greywacke per day. Some reduction was observed, however, for greater than in the control site soil. many dairy factories throughout New Zealand have alluvium overlying greywacke gravels. A description a few days following effluent application. Total nitrogen analyses, using a semi-micro found it necessary to seek alternative methods of of a representative profile is given in Table 1. The bulk density in the surface 100 mm at the Kjeldahl method (Bremner 1965) and organic disposal. The disposal site itself covers an area of 27 ha and disposal site was found to be significantly lower than matter determinations, using the 'Walkley Black' One of the most widely adopted techniques has forms part of a seasonal supply dairy farm. at the control site (735 kg m-3 compared with method (Allison 1965), showed that significant been spray irrigation onto pasture. Over a third <:f 950 kg m-3). It is likely that this decrease in bulk accumulation of both total nitrogen and organic New Zealand's 116 dairy factories now employ this density has resulted from an increase in organic matter had occurred from the 15 years of wastewater EFFLUENT APPLICATION RATES AND matter content (as seen later) coupled with irrigation. The difference in levels between the method. FERTILISER EQUIVALENTS enhanced biological activity. disposal and control sites to 600 mm depth Although observations made of spray disposal .represents an accumulation of 16 500 kg N ha-1 and By measuring application rates and considering systems suggest that the method can be a successful, Soil pH values in the surface 300 mm at the 247 OOO kg of organic matter ha-1. low-cost technique, little is known of the long term seasonal production levels it is estimated that disposal site were found to be approximately 0.5 to soil and underlying groundwater property changes approximately 15 OOO million litres of effluent ~ad 0.8 of a pH unit higher than at the control site. It is Oxygen uptake studies made on soil samples from induced by the wastewater. been applied to the site over the 15-year peno~, evident then, that the application of acidic casein the disposal and control sites revealed that soil 1963-1978. Water balance studies showed that this wastewater (with an average pH of approximately respiration increased markedly following effluent With the cooperation of the New Zealand Dairy quantity of effluent had approximately double~ total 4.5) has not caused a lowering of soil pH and, in fact, application. Seven days after effluent application, Research Institute, the Department of Soil Science deep percolation losses over the 15-year penod. has worked in the opposite direction. This oxygen uptake in the disposal site soil was five times at Massey University examined several spray observation, which lends support to previous as high as the control site level. However, after 14 disposal sites in order to detect any soil prop~rty Coupling the above information for effluent findings (Wells & Whitton 1966), probably results days, oxygen consumption values were similar. changes which may have occurred. One of the sites volume with effluent analysis (Table 2) it was from the release of Ca+ +and NH/ ions upon whey Earlier work conducted at the Te Rehunga site by Di investigated was the Tui Dairy Co-operative disposal estimated that the equivalent of 17 tonnes of decomposition. Menna (1966) demonstrated that total yeast site at Te Rehunga, which had received wastewater superphosphate and 6 tonnes of urea per ha per year numbers in irrigated soils increased by up to 1000 associated with casein manufacture since 1963. had been applied to the site. These values are about 'Plant available' phosphate levels, determined times, especially where lactose was present. It is using Olsen's bicarbonate extraction (Olsen et al. likely then, that populations of other soil micro 1954), were found to be extremely high in the organisms will be similarly stimulated by waste disposal site soil (Table 3). For all depths examined application. (down to 600 mm) the level at the disposal site was Table 1 Profile description of the Kopua silt loam at the Te Rehunga disposal site at least 5 times greater than at the control site, with Earthworm counts made in early June showed up to 20-fold differences in the surface 300 mm. that the disposal site had approximately six times as Ho1rizo111 Depth (mm) Colom Texture Structure fine crumb Apl 0-50 dark yellowish brown (lOYR 3/4) silt loam medium-fine nut Ap2 50-150 dark yellowish brown (lOYR 3/4) slightly stony silt loam Table 3 Summary of some of the chemical characteristics in surface layer soils from the very fine nut Bwl 150-300 brown (lOYR 4/3) moderately stony silt loam disposal and control sites very fine nut Bw2 300-400 vellowish brown (lOYR 5/4) slightly gravelly silt loam c 450 iight olive brown (2.5Y 5/3) slightly gravelly silt loam very fine blocky Soil parameter Disposal site depth (mm) Control site depth (mm) 0--100 100-200 200-300 0--100 100-200 200-300 Table 2 Effluent composition and estimated application rates 'Plant available' phosphate (µg g-1) 660 320 210 23 15 10 N0 -N (µg g-1) 196 24 18 46 5 Total Dissolved Total Dissolved 3 5 NH -N (µg g-1) 30 14 12 8 8 7 P inorg. P solids solids 4 Mineralisable-N (µg g-1) 716 170 Total N (%) 1.15 0.72 0.57 0.55 0.33 0.27 Total C (%) Effluent composition (mg 1-1) 205 135 360 0.40 12 300 11 500 19.7 13.3 10.5 14.4 7.6 4.7 Est. application per spraying (kg ha-1) 144 95 255 8600 8000 106 107 many earthworms in the soil profile as in the control localised and is due to a high level aquifer existing in IRON OCHRE IN DRAINAGE SYSTEMS AFFECTING POTENTIAL PRODUCTIVITY site. An examination of the earthworms collected the underlying gravels. Installation of a suitable OF YELLOW~BROWN LOAMS from both sites indicated that the waste application subsurface drainage system would do much to had also induced a change in species composition alleviate both pugging and 'pasture puUing' prob and age group distribution. Whereas earthworms lems. W .J. Climo, Department of Soil Science, Massey University, Palmerston North found at the control site were of a similar age group, those found at the disposal site represented a variety of age groups. SUMMARY AND IMPLICATIONS Imperfectly drained yellow-brown loams have a Table 2 Composition of iron ochre found in high productive potential once drained. In many yellow-brown loams and associated gleys of Studies made of the Kopua silt loam profile at the situations the life and efficiency of subsurface Taranaki EFFECT OF WASTE DISPOSAL ON FARM Te Rehunga disposal site indicate that several drainage systems is limited. Iron ochre formation MANAGE:MENT PRACTICES significant soil property changes have occurred as a can block pipes, surrounding backfill, and soil. result of 15 years' wastewater irrigation. Of major Complete blockage may occur within a few months Locality: Wiremu Road Ihaia Road Newall Road Comparing milk fat production figures for the significance are: a decrease in surface layer bulk of installation or take as long as 20 years before Soil Wiremu with Op111a Newall disposal farm with those of three neighbouring non significant decreases in efficiency are noticed. series: Patiki-Skeet inclusions Punehu density, an increase in soil pH, large increases in Site 1 Site 2 irrigated farms it is evident that the waste 'plant available' phosphate and nitrogen levels, a Medium to coarse textured soils with a perennial application has contributed to a marked increase in build up in total nitrogen and organic matter levels flow of water to subsurface drains appear to be the production (Fig. 1). Although the production and an increase in soil micro-organism and most prone to iron ochre formation (Bowler 1980). Fe 36.7 34.8 35.5 47.9 High soil and groundwater iron contents contribute Mn 0.27 0.54 0.05 0.07 difference between treatments is negligible in earthworm numbers. It is interesting to note that Mg 0.25 0.48 0.09 0.03 December, the prolonged dry spell in subsequent none of these changes would create a less favourable to the risk. These conditions are particularly c 8.0 4.1 8.7 2.7 months causes a more rapid decline in production on environment for plant growth. common in the yellow-brown loams of south N 0.61 0.34 0.48 0.17 the non-irrigated farms. Furthermore, it is signific westem Taranaki (see Palmer et al. 1982). Parts of C/N 13 12 18 16 ant that spray irrigation has facilitated an additional It is apparent that the wastewater irrigation has the Manawatu, Waikato, Bay of Plenty and month's production at the end of the milking season. increased production at the site. There is the Northland regions are also affected. possibility of a further increase in production if the The iron component of this ochre frequently No major weed or stock health problems have two problems of pugging and 'pasture pulling' can be Large tracts of land overseas with the problem of occurs as non-crystalline ferrihydrite (J.H. Kirkman, been encountered on the disposal farm, although overcome. iron ochre formation in drainage systems have pers. comm.). magnesium supplements are provided for stock as a attracted much attention. Researchers in the precautionary measure against hypomagnesaemia Observations suggest that the design and man Netherlands, England, Wales, Denmark, Canada, Both chemical and biological processes are (grass staggers). The disposal site does, however, agement of spray disposal sites has a marked impact and the U.S.A. have contributed to the body of involved in the formation of iron ochre. In general, have two problems which limit pasture production. on the success or failure of the system. Of particular knowledge about the composition, formation and soluble ferrous iron is produced under waterlogged The first of these is a pugging, or stock treading, importance are, firstly, the need to avoid ponding remedial techniques concerning iron ochres. As yet and therefore reducing conditions. As water high in induced by poor drainage and low bulk density. The during spraying and secondly, the need to ensure an the problem has had comparatively little attention in ferrous iron flows towards drainage channels, second problem is termed 'pasture pulling', whereby adequate spelling interval between applications. The New Zealand. If high investments in subsurface oxidation occurs leading to precipitation of ferric plants may be completely uprooted during stock Te Rehunga disposal site does show, however, that drainage are to be justified then the long-term iron. Ferrous iron, produced in waterlogged soil grazing. Although other factors contribute to both spray irrigation onto pasture can be an economically efficiency must be guaranteed (Kuntze 1979). and/or transported via groundwaters, is essential for the above problems it is likely that poor drainage is viable alternative for dairy factory wastewater iron ochre formation, and analyses of groundwaters Iron ochre is an amorphous to colloidal sludge, the major cause. This poor drainage is seasonal and disposal. in the Taranaki region show iron contents ranging rich in iron, alumina-silicate and carbonaceous from 0 to 35 mg/I over a depth range of 0-40 m materials, and can also contain Mn, Ca, Mg and beneath the surface and a pH range of 5.6-8.65 SOi- together with small amounts of several other (W.B. Coombridge, pers. comm.). The potential elements. Table 1 illustrates the widely varying production of ferrous iron from the soils in Taranaki 0.7 chemical composition of iron ochre reported by under waterlogged conditions is high. Two volcanic ....,,;- .._ overseas researchers. soils from Taranaki, incubated at 25°C in anaerobic o.s - ...... conditions, indicated that poorly drained soils can produce large quantities of ferrous iron. However, z: Table 1 Composition of iron ochre from drain ' when a readily available energy source is provided, a ,__,0 pipes (n=21)* o.s well drained soil can also produce large quantities of I- ' L.) ' ferrous iron (Table 3). ::::> ' Fe20 3 3.0--65.9 0 Al 0 0.2-39.3 0 ,..-.... ' 2 3 Table 3 Water extractable ferrous iron produced cc: >- MnO 0-12.9 under anaerobic conditions from two volcanic °'- <( CaO 0.06-12.8 Q 0.3 MgO 0.13-1.55 soils 1- ...... S042- 0-7.54 "3'.: ::;:: LJ_ 0 C02 0-9.04 c.c: u 0.2 ...... ,. DISPOS.~L FARM Organic matter 25.5-53.5 Soil series Ferrous iron proo111ctio111 (µg Fe2+ /g soil) U.J ...... CIN 11-30 Days: 0 4 7 10 19 1-- (..') pH 3.6--7.1 1- ~ a-_. CONTROL FARMS :::::> '--' Awatuna (poorly drained) 1.02 1.40 9.60 15.2 43.8 i:o *in% of dry matter exclusive of insoluble residue (Peterson 1966) Warea (well drained) 1.09 0.68 0.93 1.22 6.90 Warea ( + sucrose,after day 10) 37.1 0 DEC JAN F'EB MAR /A.PH It is the biotic factors which seem to make the (MONTHS) Analyses of samples taken from drains installed in TIME yellow-brown loams show a similar range of occurrence of iron ochre so variable. Iron Figure 1 A comparison between production figures of the disposal farm and the average production of three non-irrigated (control) compositions (Table 2). precipitating bacteria of the genera Leptothrix, neighbouring farms, for the period December 1977 to April 1978. Gallionella, Sphaerotilus, Naumaniella, Toxothrix, 108 109 Pseudomonas and Enterobacter are all involved in groundwaters and do not fall into this category. 13. iron ochre formation (Ford 1979). It is their bodies, In the second example, when ferrous iron is with ferric iron coatings, that form an integral part of continually introduced via groundwater, counter the iron ochre deposited in drainage systems, measures are aimed at prevention of iron precipita especially pipes. An indication of the variability of tion and settlement until water has passed through The bibliography includes all references in the CAMPBELL, I.B. 1978 iron ochre formation is given by the fact that when Soils of Rangitikei County, North Island, New Zealand. the pipe. The use of special filters with chemicals to text, whether or not they pertain to yellow-brown N.Z. Soil Survey Report 38. poorly drained soils with high iron content prevent iron precipitation, submergence of outlets to loams. Those references which do not contain CHILDS, C.W.; SEARLE, P.L.; WELLS, N. 1977 groundwaters may have drainage systems free of the prevent the aeration of pipes, use of steeper drain information on yellow-brown loams are marked with Infiltration through soil as a tertiary treatment of sewage problem. The poor design, installation and main slopes (>0.4%) and wide gaps or slots (> 1.2 mm) an asterisk(*). effluent. tenance of pipe drainage systems will also contribute have all been tried in experimental situations N.Z. Soil Bureau Scientific Report 29. 87p. CHURCHMAN, G.J.; TATE, K.R. 1982 to the problem. Pipes laid unevenly or to flat overseas but none of these techniques has been tried AITKEN, J.F.; CAMPBELL, LB.; WILDE, R.H. 1978 Characterisation of organo-mineral complexing and gradients and blocked outlets will encourage iron Soils of Stratford County, North Island, New Zealand. in New Zealand. Regular cleaning of pipes has some microaggregation in two contrasting uncultivated soils. N.Z. Soil Survey Report 42. ochre to precipitate and settle. effect, but it does not flush the iron ochre from the Journal of Soil Science. (Submitted) backfill and slots or gaps. Inspection bays need to be *ALLISON, L.E. 1965 *CLOOS, P.; HERBILLON, A.; ECHEVERRIA, J. 1968 Counter-measures rely heavily on the identifica Organic carbon. In Black, C.A. and co-workers (Ed.), installed on long pipe lines so that cleaning can take Allophane-like synthetic silico-aluminas. Phosphate tion of areas prone to iron ochre deposition and of Agronomy 9, Methods of Soil Analysis. Part 2. American adsorption and availability. place with ease. Society of Agronomy, Madison. pp.1367-1377. the source of ferrous iron. Kuntze (1979) identifies Transactions of the Ninth International Congress of Soil two main sources of ferrous iron and different Further research into iron ochre is required in ASTON, B.C. 1928 Science II: 733-743. Lime deficient areas and a hitherto unsuspected counter-measures apply to each. New Zealand. At present, local knowledge of COTCHING, W.E.; ALLBROOK, R.F.; GIBBS, H.S. 1979 malnutrition disease in sheep. Influence of maize cropping on the soil structure of two 1. Iron mobilised from within a drained area conditions and avoidance of highly prone areas is of N.Z. Journal of Agriculture 37: 145-151. high priority. Areas with high iron contents in soil soils in the Waikato district, New Zealand. ( autochthonic). *A Y ANABA, A.; TUCKWELL, S.B.; JENKINSON, D.S. 1976 N.Z. Journal of Agricultural Research 22: 431-438. and groundwaters, waters showing 'oily' surfaces, The effects of clearing and cropping on the organic 2. Iron from outside a drained area and trans *DALE, P.S. 1973 reserves and biomass of tropical forest soils. ported via the groundwater ( allochthonic). and low soil and water pH values are all prone to Elimination of root-knot nematodes from roses by Soil Biology and Biochemistry 8: 519-25. iron ochre formation. Good design, installation and chemical bare-root dips. In the first example, iron ochre formation can be maintenance of pipe drainage systems is essential if *BARROW, N.J. 1967 N.Z. Journal of Experimental Agriculture 1: 121-122. Studies on the adsorption of sulphate by soils. considered temporary, because once oxidising the full productive potential of the imperfectly *DALY, B.K.; BINNIE, H.J. 1974 Soil Science 104: 342-349. conditions are introduced subsequent iron mobilisa drained yellow-brown loams and their associated A leaching method for the extraction of acid oxalate tion is decreased. Counter-measures are based upon gleys are to be realised. *BIRCHAM, J.S.; CROUCHLEY, G.; WRIGHT, D.F. 1977 soluble aluminium and iron from soil in conjunction with the precipitation of iron before major pipe drainage Effects of superphosphate, lime and stocking rate on cation exchange teachings. pasture and animal production on the Wairarapa Plains. Communications in Soil Science and Plant Analysis 5: 507- systems are installed e.g. subsoiling, moling and Adrnowledgments N.Z. Journal of Experimental Agriculture 5: 349-355. 514. liming. Once the soil has 'browned' sufficiently (i.e. Dr M.A. Turner for guidance in analytical BIRRELL, K.S.; FIELDES, M. 1968 *DAVOREN, A. 1978 the ferrous iron has oxidised), then pipe drains can Amorphous Constituents. Chapter 6.4, pp.39-49 in Soils A survey of New Zealand peat resources. be placed in the pre-aerated soil. Unfortunately techniques; Dr J.H. Kirkman for the mineralogical of New Zealand, Part 2. Water and Soil Technical Publication 14. 157p. analyses; Dr V.E. Neall and Mr R.W.P. Palmer for N.Z. Soil Bureau Bulletin 26(2). 22lp. most of the sites in the volcanic soils investigated so DI MENNA, N.E. 1966 far tend to be caused by iron transported via valuable soil information. BIRRELL, K.S.; FIELDES, M. 1974 Yeasts in soils spray irfigated with dairy factory wastes. Extractable hydrogen and aluminium values for New N.Z. Journal of Agricultural Research 9: 567-589. Zealand soils in relation to classification and constitution. DIXON, G.M.; CAMPBELL, A.G. 1978 N.Z. Journal of Science 17: 369-373. Relationships between grazing animals and populations of *BIRRELL, K.S.; PULLAR, W.A.; SEARLE, P.L. 1977 the pasture insects Costelytra zealandica (White) and Weathering of Rotoehu Ash in the Bay of Plenty district. Inopus rubriceps (Macquart). N.Z. Journal of Science 20: 303-310. N.Z. Journal of Agricultural Research 21: 301-305. BLAKEMORE, L.C.; MILLER, R.B. 1968 DIXON, G.M.; GERARD, P.J. 1979 Organic matter. Chapter 7.2, pp.55-67 in Soils of New Effect of stocking rate on emergence, dispersal, and Zealand. Part 2. behaviour of soldier fly adults in pasture. N.Z. Soil Bureau Bulletin 26(2). 221p. N.Z. Journal of Agricultural Research 22: 507-510. BLAKEMORE, L.C.; PARFITI, R.L. 1979 DIXON, G.M.; HOLLAND, P.T. 1977 Variable charge in some New Zealand soils. Reduction of soldier fly damage to ryegrass seedlings by N.Z. Soil News 27: 85-90. insecticidal seed treatments. *BLAKEMORE, L.C.; SEARLE, P.L.; DALY, B.K. 1977 N.Z. Journal of Experimental Agriculture 5: 167-169. Methods for chemical analysis of soils. DRUCE, A.P. 1966 N.Z. Soil Bureau Scientific Report lOA. Tree-ring dating of Recent volcanic ash and lapilli, Mt BOWLER, D.G. 1980 Egrnont. The drainage of wet soils. Hodder and Stoughton. 259p. N.Z. Journal of Botany 4: 3-41. *BREMNER, J.M. 1965 DURING, C. 1972 Total nitrogen. In Agronomy 9, Methods of Soil Analysis. Fertilisers and soils in New Zealand farming. Part 2. (Ed. C.A. Black and co-workers), American N.Z. Department of Agriculture Bulletin No. 409. Society of Agronomy, Madison, pp.1147-1178. DURING, C. 1973a *BREMNER, J.M.; KEENEY, D.R. 1964 The effective relative affinity for magnesium and Steam distillation methods for determination of potassium of some soils from the North Island, New ammonium, nitrate and nitrite. Zealand. Analytica Chimica Acta 32: 485-495. N.Z. Journal of Agricultural Research 16: 1-8. BRUCE, J.G. 1978 DURING, C. 1973b Soils of part Raglan County, South Auckland, N.Z. Cation exchange capacity at field pH and its relation to the N.Z. Soil Bureau Bulletin 41. 102p. affinity of soils for individual cations. N.Z. Journal of Agricultural Research 16: 415-422. CAMPBELL, LB. 1977 Soils of part Wanganui County, North Island, New *EARL, K.D.; SYERS, J.K.; McLAUGHLIN, J.R. 1979 Zealand. Origin of the effects of citrate, tartrate, and acetate on N.Z. Soil Bureau Bulletin 40. 99p. phosphate sorption by soils and synthetic gels. Soil Science Society of America Journal 43: 674-678. 110 111 GIBBS, H.S. 1968 HOGG, A.G. 1979 EDMEADES, D.C. 1980 . . . . KIRKMAN, J.H.; McHARDY, W.J. 1980 Calcium-magnesium exchange eqmhbna ma range of New Volcanic-ash soils in New Zealand. Identification and correlation of thinly bedded Late A comparative study of the morphology, chemical Zealand soils. N.Z. Department of Scientific and Industrial Research Quaternary tephras of Coromandel Peninsula, New Information Series 65. 39p. composition and weathering of rhyolitic and andesitic Australian Journal of Soil Research 18: 251-255. Zealand. (Unpublished D.Phil. thesis lodged in the glass. EDMEADES, D.C.; JUDD, M.J. 1980 ... GRADWELL, M.W. 1968 Library, University of Waikato, Hamilton, New Zealand). Clay Minerals 15: 165-173. The moisture-holding properties of Waikato soils and The effects of lime on the magnesium status and eqmhbna HOPE, G.D. 1977 *KOHN, B.P. 1970 in some New Zealand topsoils. methods of their determination. Interactions of molybdate and phosphate with soils. N.Z. Journal of Agricultural Research 11: 631-4)54. Identification of New Zealand tephra-layers by emission Soil Science 129: 156-161. Ph.D. thesis, Massey University. spectrographic analysis of their titanomagnetites. EDMEADES, D.C. 1981 GRADWELL, M.W. 1974 *HOWORTH, R. 1975 Lithos 3: 361-367. The effect of liming on the effective cation exchange Laboratory test methods for the structural stabilities of New formations of Late Pleistocene tephras from the KOHN, B.P. 1973 soils under grazing. capacity and exchangeable cations of a range of New Okataina volcanic centre, N.Z. Some studies of New Zealand Quaternary pyroclastic Transactions 10th International Congress of Soil Science, Zealand topsoils. Abstract p.48 in 'Soils with Variable N.Z. Journal of Geology and Geophysics 18: 683-712. rocks (Unpublished Ph.D. thesis lodged in the Library, Charge' Conference 'Programme and Abstracts' 11-18 Moscow, 1: 341-350. HUGHES, H.A.; HODGSON, L.; HARRIS, A.C. 1939 Victoria University of Wellington, New Zealand). 340p. February, 1981. Massey University, Palmerston North, GRADWELL, M.W. 1976 Soils. In Land utilisation report of the Heretaunga Plains. KOHN, B.P.; NEALL, V.E. 1973 N.Z. 194p. Available-water capacities of some intrazonal soils of New N.Z. Department of Scientific and Industrial Research Identification of late Quaternary tephras for dating Zealand. EDMEADES, D.C.; O'CONNOR, M.B.; THOMSON, N.A.; Bulletin 70. lllp. Taranaki lahar deposits. N.Z. Journal of Agricultural Research 19: 69-78. TOXOPEUS, M.R.J. 1979 *HUME, T.M.; SHERWOOD, A.M.; NELSON, C.S. 1975 N.Z. Journal of Geology and Geophysics 16: 781-792. Effect of lime on pasture and animals. GRADWELL, M.W. 1978 Alluvial sedimentology of the upper Pleistocene Hinuera KUNTZE, H. 1979 Ruakura Farmers Conference Proceedings: 57-67. Pore-size distributions of some New Zealand soil groups. Formation, Hamilton Basin, N.Z. Iron clogging: Diagnosis and therapy. Proceedings of the N.Z. Journal of Agricultural Research 21: 603-4)14. *EWART, A. 1968 Journal of the Royal Society of N.Z. 5: 421-462. International Drainage Workshop, Wageningen, The The petrography of the central Nort~ Island rhyolitic l~vas. GRADWELL, M.W. 1979 JACKMAN, R.H. 1964 Netherlands, 1978, pp.452-461. Part 2: Regional petrography mcludmg notes on associated Subsoil hydraulic conductivities of major New Zealand soil Accumulation of organic matter in some New Zealand International Institute for Land Reclamation and Improve ash flow deposits. groups at water contents near field capacity. soils under permanent pasture. I. Patterns of change of ment, Bulletin 25. N.Z. Journal of Geology and Geophysics 11: 478-545. N.Z. Journal of Agricultural Research 22: 603-14. organic carbon, nitrogen, sulphur, and phosphorus. *KYLE, J.H.; POSNER, AM.; QUIRK, J.P. 1975 *PAO 1974 GRADWELL, M.; BIRRELL, K.S. 1954 N.Z. Journal of Agricultural Research 7: 445-471. Kinetics of isotopic exchange of phosphate adsorbed on FAO-Unesco Soil Map of the World, 1:5 OOO 000. Vol.I. Physical properties of certain volcanic clays. *JENKINSON, D.S.; OADES, J.M. 1979 gibbsite. Legend. 59p. N.Z. Journal of Science and Technology B36: 108-122. A method for measuring adenosine triphosphate in soil. Journal of Soil Science 26: 32-43. *FAO 1978 GRANGE, L.I. 1931 Soil Biology and Biochemistry 11: 193-199. *LEAMY, M.L.; SMITH, G.D.; COLMET-DAAGE, F.; FAO-Unesco Soil Map of the World, 1.:5 OOO OOO. Vol. X. Volcanic-ash showers. *JENKINSON, D.S.; POWLSON, D.S. 1976 OTOWA, M. 1980 Australasia. 221p. N.Z. Journal of Science and Technology 12: 228-40. The effects of biocidal treatments on metabolism in soil. V. The morphological characteristics of Andisols. Pp.17-34 in *FARMER, V.C. 1979 GRANGE, L.I. 1945 A method for measuring soil biomass. 'Soils With Variable Charge', (Ed. B.K.G. Theng). N.Z. Possible roles of mobile hydroxy aluminium orthosilicate Farming in New Zealand: North Island soils. Soil Biology and Biochemistry 8: 209-213. Society of Soil Science, Lower Hutt, N.Z. 448p. complex (proto-imogolite) in podzolisation in 'Migrations N.Z. Journal of Agriculture 10: 387-397. *JENKINSON, D.S.; DAVIDSON, S.A.; POWLSON, D.S. LEE, K.E. 1959 Organo-minerales dans Jes Temperes'. International GRANGE, L.I.; TAYLOR, N.H. 1932 1979 The earthworm fauna of New Zealand. Coloquium of C.N.R.S. Nancy, France. The distribution and field characteristics of bush-sick soils. Adenosine triphosphate and microbial biomass in soil. N.Z. Department of Scientific and Industrial Research *FARMER, V.C.; FRASER, A.R.; RUSSELL, J.D.; Pp.21-35 (Part 2A) in 'Bush sickness'. Soil Biology and Biochemistry 11: 521-527. Bulletin 130. 486p. N.Z. Department of Scientific and Industrial Research YOSHINAGA, N. 1977 *JOHNSON, C.M.; NISHITA, H. 1952 LEE, K.E. 1968 Recognition of imogolite structures in allophanic clays by Bulletin 32. Microestimation of sulfur in plant material, soils and A preliminary study of soil animals and their relationships infrared spectoscopy. GRANGE, L.I.; TAYLOR, N.H. 1933 irrigation waters. to some New Zealand soils. Chapter 10.2, pp.168-183 in Clay Minerals 12: 55-57. Field-work on soils of western Taranaki. Analytical Chemistry 24: 736-742. 'Soils of New Zealand. Part 2'. *FARMER, V.C.; FRASER, A.R.; TAIT, J.M. 1977 N.Z. Department of Scientific and Industrial Research *JUO, A.S.R.; AYANLAJA, S.A.; OGUNWALE, J.A. 1976 N.Z. Soil Bureau Bulletin 26(2). 221p. Synthesis of imogolite: A tubular aluminium silicate Report 1932-33: 33-35. An evaluation of cation exchange capacity measurements LOWE, D.J. 1979 polymer. . . . GRANGE, L.L; TAYLOR, N.H.; SUTHERLAND, C.F. 1939 for soils in the tropics. Aspects of genesis and classification of volcanic-ash soils in Journal of the Chemical Society, Chemical Commumcatrons Soils in Soils and agriculture of part of Waipa County. Communications in Soil Science and Plant Analysis 7: 751- the Hamilton Basin. 13: 462-463. N.Z. Department of Scientific and Industrial Research 761. N.Z. Soil News 27: 171-173. Bulletin 76. 85p. FIELDES, M. 1955 *KAFKAFI, U.; POSNER, A.M.; QUIRK, J.P. 1966 LOWE, D.J. 1981 Clay mineralogy of New Zealand soils, Part II. Allophane *HAQUE, I.; WALMSLEY, D. 1974 Desorption of phosphate from kaolinites. Origin and composite nature of Late Quaternary airfall and related mineral colloids. Sulphur investigations in some West Indian soils. Soil Science Society of America Proceedings 30: 348-353. deposits, Hamilton Basin. M.Sc. thesis, University of N.Z. Journal of Science and Technology B37: 336-350. Tropical Agriculture 51: 253-263. *KAMPRATH, E.J. 1970 Waikato, Hamilton. FIELDES, M. 1968 *HELFFERICH, F. 1962 Exchangeable aluminium as a criterion for liming leached *LOWE, D.J.;HOGG, A.G.; GREEN, J.D.; BOUBEE, J.A.T. Clay Mineralogy, Chapter 6.3, pp.22-39 in Soils of New Ion exchange. McGraw-Hill, New York. mineral soils. 1980 Zealand. Part 2. *HENMI, T.; WADA, K. 1976 Soil Science Society of America Proceedings 34: 252-254. Stratigraphy and chronology of Late Quaternary tephras in N.Z. Soil Bureau Bulletin 26(2). 22lp. Morphology and composition of allophane. Lake Maratoto, Hamilton, New Zealand. American Mineralogist 61: 379-390. *KENNEDY, N.M. 1980 FIELDES, M.; CLARIDGE, G.G.C. 1975 Field recognition of tephric loess (c. 42 000-15 OOO yrs N.Z. Journal of Geology and Geophysics 23: 481-485. Allophane. Pp.351-393 in 'Soil Components, Volume 2, *HENZELL, R.F.; LAUREN, D.R. 1977 B.P.) in Central North Island. McCOLL, H.P. (in press) Inorganic Components', (Ed. J.E. Gieseking), Springer Use of sex attractant traps to estimate the development N.Z. Soil News 28: 55-58. Terrestrial Fauna of N.Z. Arthropoda; Coleoptera, Verlag, New Yor.c 684p. stage of grass grub, Costelytra zealandica (White) Staphylinidae; Osoriinae. Government Printer, Wel (Coleoptera:Scarabaeidae), in the soil. *KIRKMAN, J.H. 1975 *FIELDES, M.; SCHOFIELD, R.K. 1960 Clay mineralogy of some tephra beds of Rotorua area, lington. Mechanisms of ion adsorption by inorganic soil colloids. N.Z. Journal of Agricultural Reserch 20: 75-78. North Island, New Zealand. McCOLL, H.P. 1981 N.Z. Journal of Science 3: 563-579. *HIGASHI, T.; IKEDA, H. 1974 Clay Minerals 10: 437-449. Collecting data for Osoriine staphylinid beetles in New Dissolution of allophane by acid oxalate solution. *FLACH, K.W. 1972 *KIRKMAN, J.H. 1977 Zealand up to 1979. The differentiation of the cambic horizon of Andepts from Clay Science 4: 205-211. Possible structure of halloysite disks and cylinders N.Z. Soil Bureau Scientific Report 46. 80p. spodic horizon. HODDER, A.P.W. 1974 observed in some New Zealand rhyolitic tephras. *McLAUCHLIN, J.R.; RYDEN, J.C.; SYERS, J.K. 1981 II. Panel Sobre Suelos Volcanicos de America, 1972, Pasto Physical and chemical techniques in identificatio? of Clay Minerals 12: 199-216. Sorption of inorganic phosphate by iron- and aluminium Colombia. tephra in the North Island, New Zealand. (Unpubhshed containing components. D.Phil. thesis lodged in the Library, University of *KIRKMAN, J.H. 1980a FORD, H.W. 1979 Mineralogy of the Kauroa Ash Formation of south-west Journal of Soil Science 32: 367-377. Bacterial activity and iron complexation as drain clogging Waikato, Hamilton, New Zealand). and west Waikato, North Island, New Zealand. McLINTOCK, A.H. 1959 agents. Abstract in Proceedings of the International HODDER, A.P.W. 1978 N.Z. Journal of Geology and Geophysics 23: 113-120. A descriptive atlas of New Zealand. Government Printer, Drainage Workshop, Wageningen, The Netherlands, Refractive index and hydration of rhyolitic glass of Wellington. 109p. 1978, p.451. Holocene tephras, North Island, New Zealand. KIRKMAN, J.H. 1980b International Institute for Land Reclamation and Improve N.Z. Journal of Geology and Geophysics 21: 155-166. Clay mineralogy of a sequence of andesitic tephra beds of *MA1THEWS, W.H. 1951 ment, Bulletin 25. western Taranaki, New Zealand. A useful method for determining approximate composition HODDER, A.P.W.; WILSON, A.T. 1976 Clay Minerals 15: 157-163. of fine grained igneous rocks. GIBBS, H.S. 1954 Identification and correlation of thinly bedded tephra: the American Mineralogist 36: 92-100. Soils and agriculture of Matakaoa County. Tirau and Mairoa Ashes. N.Z. Soil Bureau Bulletin 11. 52p N.Z. Journal of Geology and Geophysics 19: 663-682. 112 113 •RAJAN, S.S.S. 1975a *METSON, A.J. 1961 *OLSEN, S.R.; COLE, C.W.; WATANABE, F.S.; DEAN RYDEN, J.C.; s.'YE'.RS, J.K.; McLAUGHLIN, J.R. 1977c Methods of chemical analysis for soil survey samples. L.A. 1954 ' ·Adsorption of divalent phosphate on hydrous aluminium Effects. o~ ioruc st;ength on chemisorption and potential N.Z. Soil Bureau Bulletin 12. 208p. Estimation of available phosphorus in soils by extraction oxide. determmmg s?rpt1on of phosphate by soils. with sodium bicarbonate. Nature 253: 434-436. Journal of Soil Science 28: 62-71. METSON, A.J. 1974 U.S. Department of Agriculture Bulletin 939. Magnesium in New Zealand soils. I. Some factors •RAJAN, S.S.S. 1975b SAUNDERS, W.M.H. 1965 governing the availability of soil magnesium. A review. PALMER, R.W.P.; NEALL, V.E.; POLLOK, J.A. 1982 Mechanism of phosphate adsorption by allophane clays. Phosphat~ retention by New Zealand soils and its N.Z. Journal of Experimental Agriculture 2: 277-319. Soils of Egmont County and part Taranaki County. N.Z. Journal of Science 18: 93-101. re~atJ.onsrup.to free sesquioxides, organic matter and other soil properties. N.Z. Soil Survey Report 64. 68p. RA.JAN, S.S.S. 1975c METSON, A.J.; BLAKEMORE, L.C. 1978 N.Z. Journal of Agricultural Research 8: 30-57. Sulphate retention by New Zealand soils in relation to the *PARFITI, R.L. 1978 Phosphate adsorption and the displacement of structural competitive effect of phosphat.e. Anion adsorption by soils and soil materials. silicon in an allophane clay. *SCOTI, N.M. 1976 N.Z. Journal of Agricultural Research 21: 243-253. Advances in Agronomy 30: 1-50. Journal of Soil Science 26: 250-256. Sulphate contents and sorption in Scottish soils. Journal of the Science of Food and Agriculture 27: 367-372. METSON, A.J.; BROOKS, J.M. 1975 *PARFITI, R.L.; FRASER, A.R.; RUSSELL, J.D.; •RAJAN, S.S.S.; PERROTI, K.W. 1975 Magnesium in New Zealand soils. II. Distribution of FARMER, V.C. 1977 Phosphate adsorption by synthetic amorphous aluminosili •SEARLE, P.L.; DALY, B.K. 1977 exchangeable and 'reserve' magnesium in the main soil Adsorption on hydrous oxides. II. Oxalate, benzoate and cates. l?e de.term!nation of aluminium, iron, manganese and groups. phosphate on gibbsite. Journal of Soil Science 26: 257-266. silicon m acid oxalate soil extracts by flame emission and N.Z. Journal of Agricultural Research 18: 317-335. Journal of Soil Science 28: 40-47. atomic absorption spectrometry. •RAJAN, S.S.S.; PERROTI, K.W.; SAUNDERS, W.M.H. Geoderma 19: 1-10. METSON, A.J.; GIBSON, E.J. 1976 PARFITI, R.L.; HENMI, T. 1980 1974 Magnesium in New Zealand soils. V. Distribution of Structure of some allophanes from New Zealand. Identification of phosphate reactive sites of hydrous *SOIL CONSERVATION AND RIVERS CONTROL COUN exchangeable, 'reserve', and total magnesium in some Clays and Clay Minerals 28: 285-294. alumina from proton consumption during phosphate CIL 1971 representative soil profiles. PARFITI, R.L.; FURKERT, R.J.; HENMI, T. 1980 adsorption at constant pH values. Land Use Capability Survey Handbook, 2nd edition, Government Printer, Wellington. N.Z. Journal of Agricultural Research 20: 163-184. Identification and structure of two types of allophane from Journal of Soil Science 25: 438-447. METSON, A.J.; GIBSON, E.J.; LEE, R. 1977 volcanic ash soils and tephra. RENNES, A.M.D. 1978 *SOIL CONSERVATION SERVICE 1972 Magnesium in New Zealand soils. VI. Magnesium Clays and Clay Minerals 28: 328-334. Field and laboratory studies of the movement and Soil survey laboratory methods and procedures for co~lecting soil s?IDples. U.S. Department of Agriculture, fractions and inter-relationships. *PERROTI, K.W. 1978a reactions of phosphorus in soils. Ph.D. thesis, Massey Soll Conservation Service, Soil Survey Investigation N.Z. Soil Bureau Scientific Report 31. lOOp. The influence of organic matter extracted from humified University. Report No. 1. 63p. MINISTRY OF AGRICULTURE AND FISHERIES 1977 clover on the properties of amorphous aluminosilicates. I. RIJKSE, W.C. 1974 *SOIL SURVEY STAFF 1975 Farming in Taranaki. Advisory Services Division, Ministry Surface Charge. Definition: Boundaries between yellow-brown pumice Australian Journal of Soil Research 16: 327-339. soils and related or associated soils. Pp.22-27 in 'Soil Soil Taxonomy. A basic system of soil classification for of Agriculture and Fisheries, New Plymouth. making and interpreting soil surveys. *PERROTI, K.W. 1978b groups of New Zealand. Part 1: Yellow-brown pumice *MINISTRY OF AGRICULTURE AND FISHERIES 1979 U.S. Department of Agriculture Handbook No. 436. 754p. The influence of organic matter extracted from humified soils.' (Ed. N.E. Read). 251p. Soil and plant analysis at Ruakura. Plant and Analytical STEWART, RB.; NEALL, V.E.; POLLOK, J.A.· SYERS Chemistry Group, Ruakura Soil and Plant Research clover on the properties of amorphous aluminosilicates. II. RIJKSE, W.C.; WILDE, R.H. 1976 Phosphate retention. Soil map of the King Country-Sheet 1. Scale 1:63 360. J.K. 1977 ' ' Station, Hamilton. Australian Journal of Soil Research 16: 341-346. N.Z. Soil Bureau Map 17011. Parent material stratigraphy of an Egmont loam profile *MOKMA, D.L.; SYERS, J.K.; JACKSON, M.L.; CLAYTON, Taranaki, New Zealand. ' PETERSEN, L. 1966 RIJKSE, W.C. 1976 R.N.; REX, R.W. 1972 Australian Journal of Soil Research 15: 177-190. Aeolian additions to soils and sediments in the South Ocherous deposits in drain-pipes. Soil map of the King Country-Sheet 2. Scale 1:63 360. Acta Agriculturae Scandinavica 16: 120-128. N.Z. Soil Bureau Map 17012. STOUT, J.D. 1973 Pacific area. Soil ecology. Pp.131-154 in 'The Natural History of New POHLEN, LJ. 1947 RIJKSE, W.C. 1980 Journal of Soil Science 23: 147-162. Zealand'. (Ed. G.R. Williams). Reed, Wellington. 434p. Soils and some related agricultural aspects of mid-Hawkes Soils and agriculture of Waiapu Valley, East Coast, North NEALL, V.E. 1972 STOUT, J.D. 1978 Tephrochronology and tephrostratigraphy of western Bay. Island, New Zealand. N.Z. Department of Scientific and Industrial Research N.Z. Soil Survey Report 60. 86p. Effect of irrigation with municipal water or sewage effluent Taranaki. on the biology of soil cores. II. Protozoan fauna. Bulletin 94. 176p. *RODRIQUE, L.; DECLERK, F.D. 1975 N.Z. Journal of Geology and Geophysics 15: 507-557. N.Z. Journal of Agricultural Research 21: 11-20. *PRESTIDGE, R.A. 1978 Study by electron microprobe of the homogeneity of *NEALL, V.E. 1976 Effects of pasture height on intrapaddock distribution, amorphous silico-aluminas of variable composition. *SYERS, J.K.; EVANS, T.D.; WILLIAMS, J.D.H.; MUR- Volcanology of Egmont National Park. Pp.56-62 in DOCH, J.T. 1971 'Egmont National Park', (Ed. J.H. Fullarton). Egmont adult emergence, and adult flight activity of soldier fly Comptes Rendus Academic Des Sciences, Paris (C) (Inopus rubriceps Macquart:Stratiomyiidae). 280-. 1061-1063. Phosphate sorption parameters of representative soils from National Park Board, New Plymouth. Rio Grande do Sul, Brazil. N.Z. Journal of Agricultural Research 21: 553-537. *ROSS, C.S.; SMITH, R.L. 1955 NEALL, V.E. 1977 Soil Science 112: 267-275. Genesis and weathering of Andosols in Taranaki, New PULLAR, W.A. 1967 Water and other volatiles in volcanic glasses. Volcanic ash beds in the Waikato District. American Mineralogist 40-. 1071-1089. *TAMM, 0. 1922 Zealand. Eine Methode zur Bestimmung der anorganischem Earth Science Journal 1: 17-30. RUSSELL, F.C.; DUNCAN, D.L. 1956 Soil Science 123: 400-408. Komponente des Gelkomplexes im Boden. PULLAR, W.A. 1978 Minerals in pasture: deficiencies and excess in relation to N.Z. SOIL BUREAU 1954 Medde/anden fran Statens Skogs forso Kningsinstitut Tirau 'Ash' comment. General survey of the soils of North Island, New Zealand. animal health, with a foreword by Herbert Greene. 2nd 19: 387-404. N.Z. Journal of Geology and Geophysics 21: 271-272. edition. N.Z. Soil Bureau Bulletin 5. 286p. TAYLOR, N.H. 1933 PULLAR, W.A. 1979 Commonwealth Agricultural Bureau of Animal Nutrition, N.Z. SOIL BUREAU 1968a Soil processes in volcanic ash beds (Part II). Soil units of the North Island reconnaissance soil Technical Communication No. 15. 170p. General Survey of the soils of South Island, New Zealand. N.Z. Journal of Science and Technology 14: 338-352. survey: East Coast and Central North Island Regions. N.Z. Soil Bureau Bulletin 27. 404p. RUSSELL, M.; PARFITI, R.L.; CLARIDGE, G.G.C. 1981 N.Z. Soil Bureau Record 64. 21p. Estimation of the amounts of allophane and other minerals TAYLOR, N.H. 1948 N.Z. SOIL BUREAU 1968b Soil Map of New Zealand 1:2 027 520. PULLAR, W.A.; BIRRELL, K.S. 1973a in the clay fraction of an Egmont loam profile (Andept) Soils of New Zealand. from New Zealand. N. Z. Soil Bureau Map 280. N.Z. Soil Bureau Bulletin 26 (3 vols). Age and distribution of Late Quaternary pyroclastic and associated cover deposits of the Rotorua and Taupo area, Australian Journal of Soil Research 19: 185-195. TAYLOR, N.H. 1953 NWASCO 1974 North Island, New Zealand. RYDEN, J.C.; SYERS, J.K. 1977 The soil pattern, part of the ecological significance of the Erosion map of New Zealand, 1:250 000. National Water central North Island ash showers. N.Z. Soil Survey Report 1. Rationalization of ionic strength and cation effects on and Soil Conservation Organisation, Wellington, New phosphate sorption by soils. 2nd Annual Reportof N.Z. Ecological Society 1953. Zealand. PULLAR, W.A.; BIRRELL, K.S. 1973b Journal of Soil Science 26: 395-406. TAYLOR, N.H. 1964 Parent materials of Tirau silt loam. NWASCO 1975-1979 The classification of volcanic ash soils in New Zealand. In N.Z. Journal of Geology and Geophysics 16: 677-686. RYDEN, J.C.; SYERS, J.K. 1977 New Zealand Land Resource Inventory Worksheets, Origin of the labile phosphate pool in soils. Meeting on the classification and correlation of soils from 1:63 360. National Water and Soil Conservation Organisa *PYMAN, M.A.F.; KNUIMAN, M.; ARMITAGE, T.M.; Soil Science 113: 353-361. volcanic ash, Tokyo, Japan, 11-27 June. tion, Wellington, New Zealand. POSNER, A.M. 1979 FAO World Soil Resources Reports 14: 101-110. Examination of the heterogeneity of amorphous silico RYDEN, J.C.; McLAUGHLIN, J.R.; SYERS, J.K. 1977a *OADES, J.M.; JENKINSON, D.S. 1979 Mechanisms of phosphate sorption by soils and hydrous TAYLOR, N.H.; COX, J.E. 1956 Adenosine triphosphate content of the soil microbial aluminas and allophanes using the electron microprobe. The soil pattern of New Zealand. Journal of Soil Science 30: 333-345. ferric oxide gel. biomass. Journal of Soil Science 28: 72-92. N.Z. Institute of Agricultural Science Proceedings. Soil Biology and Biochemistry 11: 201-4. RAESIDE, J.D. 1956 RYDEN, J.C.; McLAUGHLIN, J.R.; SYERS, J.K. 1977b TAYLOR, N.H.; POHLEN, I.J. 1962 O'BYRNE, T.N. (in prep) Yellow-brown loams of the South Island. Time-dependent sorption of phosphate by soils and Soil survey method. Soil map of Wallace County. N.Z. Soil News 1: 9-10. hydrous ferric oxides. N.Z. Soil Bureau Bulletin 25. 242p. Journal of Soil Science 28: 585-595. 114 *THENG, B.K.G. 1979 Soil Environment and Fertility Management in Intensive The origin of variable charge in soils- a personal view. Agriculture (SEFMIA), Japan 1977. Tokyo, Japan, N.Z. Soil News 27: 76--84. Society of the Science of Soil and Manure. *THOMAS, R.F. 1973 *WADA, S.; WADA, K. 1977 Determination of particle size distribution for fine-grained Density and structure of allophane. soils. Method E4B: In 'Test methods for soil engineering'. Clay Minerals 12: 289-298. N.Z. Soil Bureau Scientific Report lOE. WARD, W .T . 1967 THOMSON, N.A.; RYS, G. ; CARPENTER, A 1978 Volcanic ash beds of the lower Waikato Basin, North Control of manuka beetle. Island, New Zealand. Proceedings N.Z. Weed and Pest Control Conference N .Z. Journal of Geology and Geophysics 10: 1109- 1135 . 31 : 164 - 166. WATSON, R.N.; WRENN, N.R . 1978 TOMLINSON, A.I. 1976 Argentine stem weevil control in maize. In New Zealand Atlas. (Ed. I. Wards). Government Proceedings N.Z. Weed and Pest Control Conference Printer, Wellington. 292p. 31: 9~102. *TONKIN, P.J. 1967 WELLS, N.; FURKERT, R.J. 1972 Note on the occurrence of Taupo Pumice in the Hamilton Bonding of water to allophane. Basin. Soil Science 113: 110--115. Earth Science Journal 1: 31. WELLS, N. ; WHITTON, J.S. 1966 TONKIN, P.J. 1970 The influence of dairy factory effluents on soil and plant The soils of the south-eastern sector of Egmont National composition. Park. N .Z. Journal of Agricultural Research 9: 565-575. Earth Science Journal 4: 3~57 . *WILCOX, R.F. 1965 TOPPING, W.W. 1973 Volcanic ash chronology. Pp.807--816 in 'The Quaternary Tephrostratigraphy and chronology of Late Quaternary of the United States, VII INQUA Congress'. Princeton eruptives from the Tongariro volcanic centre, N.Z. Press, New York. N .Z. Journal of Geology and Geophysics 16: 397-423. WILDE, R.H. 1974 TUOHY, M.P. 1980 Soils of the Westmere series in Wanganui District, New A physical, chemical and mineralogical study of allophanic Zealand, and their relationships to adjacent soils. materials used as subgrades for road in Taranaki. N.Z. Journal of Science 17: 475-492. Dip.Ag.Sci. dissertati