Soils of Chatham Island (Rekohu) Fronlis icce: 11nproved pastures Tiki larolin phase, on clay, strongly rollink near uitand tminshil’ NEW ZEALAND DEPARTMENT OF SCIENTIFIC AND INDUSTRIAL RESEARCH

N. H. TAYLOR

Director

SOIL BUREAU BULLETIN 19

SOILS OF CHATHAM ISLAND (REKOHU)

By

A. C. S. WRIGHT

Soil Bureau

1959

Price: Paper cover, 15s. Quarter cloth, 20s. N.g. Soil Bur. Bull. 19.

60 pp. 22 figs, 5 tables

R. E. OWEN. GOVERNMENT PRINTER. WELLINCTON. NEW ZEALAND -lm CONTENTS Page

Introduction 7 .. .. Soils 10 The Pattern of the .. .. 16 Factors Concerned in Development of the Soil Pattern the .. . . 16 Geology .. . . 20 Climate .. . . 22 Flora Fauna and .. .. Soil Pattern 29 Historical Factors Causing Modification of the .. ..

Pedological Significance of Soil Pattern 31 the .. ..

Agricultural Significance of Soil Pattern 32 the . . . . Elsewhere 34 Relationships with Soils of New Zealand Mainland and the . . 36 Development Potential of Soils the .. . . Acknowledgments 38 .. . . Appendix 39

...... 39 Description of Soil Types and Their Plant Nutrient Status . . . . Soil Chemistry (by R. B. Miller and L. C. Blakemore) 54 . . ..

References 58

...... 60 Index Soils to . .. . .

Map (in pocket)

Extended Legend (in pocket) INTRODUCTION

grouped Chatham under Lieutenant Chatham ishind is the largest of la islands the armed tender forty-fourth parallel latitude in William Broughton voyaging independently to about the of south longitude 17fic It lies rendezvous with Captain George Lancouver at the vicinity of west. at about South Tahiti, group; landing was made on ann miles east of Lyttleton in the Island of sighted the a The island itself New Zealand (fig 1). the main island (Vancouver 1798). islands in Chatham formally Chatham Island and in due There are three main the was named group Admiralty group: Chatham (formerly given the alternative course the appeared on charts There least names of liekobu and Wharekauri) of 224,000 acres, under the same name. are at three other in Pacific* Pitt (Rangiauria), of 15,000 acres, and South-East islands of the same name the and the Island (Itangatira) of about 640 acres. The remain- adoption of one or other of the Polynesian names for island be is not ing islands are much smaller, some little more than the main might a suggestion that between rock pinnacles. Only Chatham and Pitt are occupied without merit. To avoid confusion things group permanently, although sheep are still grazed on the pertaining to the as a natural unit, and things island, in small outlying islet of Alangere. pertaining specifically to the main this be Chatham report the former will referred to as islands or Chathams and the latter as Chatham n island.

The approach from the north, or.from the east, or

from the north-west raises a low and somewhat double -- uninspiring landfall whose chief feature is a From rank of isolated conical bills. the south the a land mass emerges with an almost smooth outline, proves be which on closer inspection to the summit point of a forbidding line of high cliffs. The highest island, Oropuke ft), behind on the (938 stands close barrier but even here, as elsewhere on this of cliffs island, landscape is of subdued relief. the the gentle predominate: Throughout the island, slopes is flat less 940 of the topography to rolling, and than 20 consists of steepland (fig. 2). Island is like 0 Outhne, Chatham shaped a ALAN broad Maori anchor-stone: narrow in the waist and at either end. It has a total area of approximately 224,000 acres, but no less than 49,300 acres (22’’,) is by lakes lagoons and I2,900 acres - occupied and dune (Gof,) consists of unstable beach and sand. The stable land surface comprises some 161,800 island. acres, only 720,, of the area of the -r - -- geography A brief general account of the of the ------.o Chatham group has been given by Falla (1950) and oo , more detailed information on various aspects of be found in agriculture, forestry, and wildlife can a I ig. 1. location of Chadunn Islands in relation to No\\ Zealand

*Chatlunn Island in the Manallanes region of southern The Chatham island . lur name 15 CommonlY used Chile (lat. $(P 40’ S; long. 74’ 20’ W). group being Chatham island in Marshall archipelago. the largest island in the in addition to the Central I i whole group. It commem- the name applied to the al-ejl a lectorSR.Cir sland) in is et. tol it the orates the OCCasion \then, in the summer of 1791. (hilapagos group (Int, I 0’ S; long. 80* 34’ W). number of New Zealand Government unpublished During past population the century the of the departmental in particular Madden reports, those of Chathams has fluctuated between 400 and 700. (1952), Patterson (1951), Connell (1938), Barron Today, with about 500 people, the population is (1952), Howse (1953). These and reports clearly 150 fewer than in 1861, and there is a very high show development proportion that of the natural resources of (nearly 500/o) under the age of 20. The islands has lagged far behind of the that the rest of number of adults on the islands is less than 300 and, New Zealand. apart from about 40 temporary residents living The Chatham Islands part Dominion are of the mainly in Waitangi township, they are mainly New Zealand. They have of the status of a county, sheep farmers living on about 90 farms scattered islanders and the are empowered to elect a county throughout Chatham Island and on one or two The Government is council. senior representative a farms on Pitt Island. The annual report of the from commissioner appointed the staff of the Department of Island Territories for 1951 shows Department of Island Territories. The islanders livestock that the maintained on farms in the have had parliamentary group representation since 1922, consisted of 127,000 sheep, 5,000 cattle, and in as voters either of the mainland electorates of 400 horses. Freight charges on produce shipped to Lyttleton (for Europeans) Western Maori or (for the mainland are high, and if the passage is a rough Maoris). one livestock may lose condition markedly before

176 45’ 176630’ 176ois’

E FLAT TO ROLLING

MS MOD. STEEP TO STEEP

M STEEP TO VERY STEEP

:i :::: 176 45 176015’ 176 30

Fig. 2. Land slope map of Chatham Island

8 In year industries, so islanders can con- reaching the saleyards. an average the that the themselves development in farmers on the Chathams send over to the mainland tribute more tolvarcls the cost of the This fmancial or some 3,000 bales of wool, 20,000 head of sheep, and islands. might require considerable be given 250 head of cattle. Under existing conditions on other assistance, but before this can the Chathams, farming pays quite but profits resources of the island require to be sur- the well natural from potential for further development are modest in comparison with those similar veyed and their classes of land on the mainland. estimated. The reconnaissance soil survey of 1985 was one The problem of of communication with the rest purpose of these surveys. The was to map the New Zealand has never been satisfactorily solved, mam soil types and, by establishmg correlations fhe farming industry is, as yet, too small to support with. similar. soils. on the mainland whose farming fully or to subsidise. . a regular shipping service, and potentialities. are well known, achieve some esti- is for several months in the winter there no surface potential . mate of the development in respect of communication with the mainland, apart from an industries. dependent upon the soil. It was designed occasional fishmg. boat. Landing. facilities. . for air- be a rapid. stocktakmg. and correlation. survey of yet developed permit to craft are not adequately to group. bad the soil. resources of the Unfortunately, Roading, scheduled services. the chief means of Island; weather restricted the survey to Chatham internal communication, is but poorly developed Pitt Island was not visited.. and at some seasons between distant farms travel This bulletin opens with a general account of the is exceedmgly. . As with. so many other still tedious. in pattern chief components the soil. and their poor is isolated communities, access accepted as a proceeds relationships. to mainland soils,. and then normal feature of island life and people are harden- a description. . of the various factors in the island. Many okler mhabit-. to ed to these conditions. of the pattern. environment mainly. responsible. for the soil. by, do not reahse. ants are not overconcerned or following deals ’ This. section. and one, which by Chatham the the limitations. . . imposed the way of briefly. with. history of land use in Chathams, particularly younger the the life. Many others, . amongst the go bring out a number of important points that generation and amongst recent settlers, wish. most far towards explaining. the present state of agri- see conditions. on . brought earnestly to the island provide . be import- culture and also leads that will nearer those pertaining in rural districts on the . future land development is in- ant in the when mamland.. Progress towards a more satisfactory . . . . . tensified. More detailed Information about Individ- way of life is undoubtedly being made, but the rate nal types of soil. and related matters, which will of progress is hampered considerably. by lack of probably be of less interest to general readers, is money for development projects. provided. m. an appenchx.. .This. appendix. includes Local rates collected by the county council are detailed descriptions of the main soil types with payable plant raised indirectly by a surcharge on all notes on their nutrient status and an estimate individual potential for or goods entering or leaving the island by the steam- of their agricultural development. Further information ship service. The annual amount collected by this silvicultural plant soil means barely covers the county maintenance costs about the nutrient content of certain is provided in brief and leaves nothing over for new development work. types a table of analyses, with Over the past three decades, the mainland has notes on the methods of soil analysis used and a pub- discussion features disclosed in contributed ever-increasing amounts towards short on the main for data. This information was lic expenditure in the Chathams, clearly the the analytical chemical C. Blakemore mainland cannot leave the islanders unattended in prepared by R. 13. Miller and L. of Soil Bureau. As possible detailed regard to health services, schools, shipping subsid- much as of the in ies, and similar matters. The point has been reached information is summarised an extended soil for is where the cost per islander is quite considerable and legend, intended use with the soil map, which The legend mainlandauthoritiesareconcernedtoknowwhether on a scale of 1:100,000. extended and in folder inside something more cannot be done to help the island the soil map are contained a the bulletin. develop existing agricultural industries, or start new rear cover of the

9 THE PATTERN OF THE SOILS

This general section of the bulletin comprises a much less extensive, occurring usually in small description Chatham patches of the soils of Island. For this isolated and having an aggregate area of purpose the soils are referred to by their common only 2,940 acres. Most of the lowland bogs are local i.e., "volcanic or name, "peat soils", soils", "lowmoor" or basin bogs whose development is promoted etc., or in the case of the soil without a local name - mainly by the inio\v of ground water schist soil". Under each subbearling the main from adjacent land of higher relief. The total extent kinds of soil recognised and mapped during the of basin bogs is 10,620 acres. The raised bogs of the pedological survey are listed and their classification lowlands usually occur as mounds in the centre of is indicated. The pedological peat-fillecl terms used in classifi- basins. These mounds act like sponges, General Survey cation are those of the of the Soils forming a reservoir for rainwater, which enables North Island, peripheries gradually of New Zealand (N.Z. Soil Bureau, their to creep outwards, filling A places, 1904). complete list of soil units shown on the the basins in which they form. In a few low- soil map and arranged in pedological order are land depressions have become completely filled given in table 1 on p. 14. through the growth of systerns of raised bogs, although, more commonly, the growth of the latter periodically presence appears to be restricted by the "PEAT AND PEAT SOILS" of too much water in the surroundmg depression. Peat and soils derived from peat occupy DO% (or There would appear to be a delicate balance: the 102,l 10 acres) of the kind surface of Chatham Island grow raised bogs cannot unless the central reser- (Hg. 3). Of no less 87,490 this total, than acres com- voirs are charged with rainwater and no advance is prise peats and peat soils developing on "highmoor possible if the peripheral area is flooded. The most or raised (Harris 1956) ombrogenous bogs where rapid advance is made when the central reservoir is peat development promoted is largely by rain- charged with water and the surrounding land is water held in the spongy undermass. Bogs of this slightly drier: hence, possibly, the much greater rate type form a more or less continuous blanket over of growth of peat on the uplands. gently undulating landscape of southern the the -1 he raised bog peats and many of the basin peats uplands. On the 10 viands, boy of are this type are oligotrophic (poor in mineral bases, particularly peats calcium) and the remainder of the basin are considered to be no better than mesotrophic (moder- ately poor in mineral bases) although no samples were taken for analysis. Lowland peats which are assumed to be of a mesotrophic nature have been mapped over an area of 5.1(in acres. The assumption presence plants is based upon the of normally re- quiring a soil with a moderately high base status, plant and the source of this extra nutrient supply is be quantities considered to small of stream alluvium lowland entering the depressions. They would thus be classed as slightly mineral-enriched peats. Another type of mineral enrichment occurs where there have been additions of ivind-blown quartz .7 Such peats be sand. sand-enriched appear to no fertile peats lowlands more than the normal of the and accordingly are regarded as being oligotrophic. Peats moderately enriched with quartz sand cover . ’ EC ar a of ar s. Where the boggy REST OF LAND

10 later by peat and peaty sand are developed. The peat com- former soil, buried and somewhat modified peat blanket. Patches of mineral ponent in this complex is usually strongly enriched the advancing by burning on with quartz sand. The sandy peat - peaty sand soil exposed are most common the located periphery complex covers a total area of 3,010 acres. The re- uplands and are usually near the Awainunga peats peat soils, where mainder of the basin peats of the lowlands are not of the and the peat is Areas showing visibly mineral enriched (except for occasional undermass relatively shallow. patchwork have been mapped as a layers of volcanic ash in the undermass) and appear a of this type basin peats complex, in which mineral soils are almost as to be oligotrophic. Lowland without soil peat peat mineral enrichment cover a total area of 4,920 acres. common as and soils, under the name peats Rekohu-Awainunga complex. Since, technically, All the above-mentioned are to some is derivative soil extent soil forming. Peat soils are least common on this complex a of the organic high proportion bogs lowlands group and contains a relatively the raised of the and are most common peats long peat are included in the classification where mesotrophic basin have been used of soil, they for farming. During the soil reconnaissance, no of organic soils. pattern In areas mapped as organic soils, a attempt was made to map out the of the addition to peats, great many of mineral soils show a surface peat soils separately from the or even attempt the proportion peat present in development of forest-litter peat, ranging in thick- an estimate of the of soil form peat in Chathams from I in, more 12 in. These the a peat area. Most of the areas the ness to than or Ao horizon of soil and have been modified from their natural state but "mor" (Muller 1879) the balance between have not yet reached a high level of development their thickness represents a the and for agricultural or silvicultural purposes: they can rate of accumulation of organic residues their peat decomposition by micro-organisms. best be described as moditled but undeveloped rate of soil peat However, species in plant assemblage of areas and the proportion of soil varies accord- certain the produce litter history individual In many cases, Chathams a large volume of that ing to the of areas. the decompose, in development burning of the original bog vegetation was followed is slow to resulting the quasi-natural deep layers "mor" or forest litter by grazing and a gradual return to of unusually of by further peat. Where is occurring on mineral soils conditions, followed attempts at reclam- this identical periods at with peat bogs supporting ation interspersed with when efforts contiguous The boundary between mineral soils development were temporarily abandoned. vegetation, the the is inevitably somewhat detailed soil pattern shows all stages from newly and the organic soils disappearing forming peat soils to older soils under arbitrary. peat, but details So widespread are peats and soils derived a new mantle of raw no of this the present from peat on Chatham Island, that mineral soils pattern can be shown on the soil map, which picture clinging precariously is intended to present only the broad of the have often the appearance of fringe blanket of peat or occur only on soil resources of the island. The organic soils, as to the of a peat protuberances break through the peat blanket. rnapped on this survey, are mixtures of soils that parent peats. They have been A example is seen where conical volcanic and their associated striking peat-covered plains in the mapped under six separate names, as follows. hills rise above the The flat land is northern part of the island (tig. 4). from bog peats raised peat hill wainmma- by Awainunga and the soils are uplands .. .. occupied laptaka. derived from basaltic rocks. fr bog peats I 1 mesotrophic, weakly enriched with alluviany latame. "VOLCANIC SOILS" oligatrophic, moderately enriched with I’ateriki The largest group of soils on Chatham quartzsand .. .. second ennched basaltic oli troph inti. Island are derived from basic tuffs and ,ndstrow41y 1-lapupu. "volcanic and are locally known as soils". oligotrophic, without noticeable enrich- rocks Alauterc. 26,060 and are ment ...... These cover a total area of acres to Waitangi parent peat soil be found mainly in the vicinity of town- in some cases the material of the peat have been and along western edge of the southern and even the undermass completely ship the These soils range frorn bright clays, destroyed by fire so that the mineral substratum uplands. This is fertile and easily farmed near the coast, has emerged at the surface. substratum relatively become progressively greyer in hue, rarely rock; rnore often it is weathered material to soils that podzolised hori- duller in and more difficult to farm as one showing strongly gleyed and soil colour, periphery probably horizons a moves inland towards the of the upland zons. These are the upper of

11 Phom: R. L. Wa/ crs Fig. 4. Conical basalt hills rising abme peat catered northern plain Waitangi West, near liangitihi hill soils on slol 1 Alvainunga peat plain. soils on

peats. In the vicinity of Waitangi township, visitors often remark on the apparent similarity in appear- between ance the (’hatham soils and the volcanic soils in Waikato; but point ash the at the where pass these soils under the peat blanket they have bleached fairly topsoils and strongly cemented sub- soils and are more reminiscent of the "gumland" soils of Northland (Taylor and Sutherland I033). Between good poor the soils at the coast and the peat soils near the blanket there is a soil of moder- ate fertility, which represents an intermediate development stage in the sequence. The soils from basaltic basic tuff and rocks are classified as brown granular Clays 308 have been mapped five 1111der 1-ig. Rangitibi hill Taupeka Station .1 soils near showing names: broadleased remnants of forest behis- basalt blutts

imm basic tuit (Tiki suite) immature stage .. .. Tiki. semimature Alangans. SOILS" stage .. .. "SANDY submature stage Tuku...... There is quartZ from basaltic rocks (Itangitibi suite) an abundance of sand around the immature stage .. .. Rangitibi northern shores of ( hatilarn Island, and accumula- semimature stage Hokopoi. .. .. dune intervals .. tions of sand OCCur at along the north liangitihi Hokopoi and soils are mainly restricted coast, and along both eastern and western sides of hill to moderately steep slopes (fig. 5). the waist of the island. Soils formed from these

12 Thus development in smals are markedly sandy in texture and are recog- the sequence of soil the from young farmers "sandy The youngest sandy soils of Chatham island is a nised by the as soils". yellow-brown a bleached sand podzol, and dunes lie close behind the shoreline, where they are sand to is gradually stabilised under sand-binding vegetation, the complete range of sandy soils classified as Soils frorn Aeolian Sand. They are mapped Marram grass is often planted to hasten this PodZolic process. With stability and ageing comes consolida- under four names: for holding Kekerione. tion and an improved capacity water, young stage . .. permits forest immature stage Te One. which the develolxnent of a cover, .. .. semimature stage .. .. Rapunni. Che forest on seaward side. of the dunes is liairakau. the nature stage .. .. usually dominated by karaka or a mixture of broad- dunes leaved species. Further inland where the are proportion older, the forest contains a smaller of proportion broadleaved species: the of tree-ferns increases and Dracophyllion arboream and a thin "SCHIST SOILS" mantle forest peat is formed on the surface of the of quartzose-feldspathic ground Soils derived from schist soil. This succession of vegetation above the had rocks are almost contined to the northern of is matched by a development sequence below the island. In closely resemble the many respects they soil surface. The soils of the most recently stabilised podzols. Topsoils are pale grey to pinkish gradual dark- the sand dunes show only a build-up of white in colour and the subsoil is usually strongly coloured humus in their Under the broad- topsoils. patches brown cemented. There are a few small of leaved forest soils show a stronger degree of the be found sandy clay derived from schist to at the compaction, and well formed structural aggregates extreme edge of the coast under coastal scrub and present. Topsoils dark brown reddish are are to young it is considered these represent a stage black. With gradual infiltration of species whose that in development of podzolised schist soils. form laver the the residues tend to accumulate and an acid The younger schist soils are small and below areas of too of peat on the soil surface, the mineral soil dispersed to show on the soil map and only becomes leached and pale in colour. Individual lidely one soil formed from schist has been mapped, under Dracophy//tern trees may produce individual areas Pukeraki. Pukeraki soils cover some in the name of strongly leached soil at this stage the ecological submature stage forest gives 6 180 acres, and are classed as the sequence. Where the broadleaved way of a podzolic soil from sedimentary rock. completely to Dracop/tyllum forest the associated podzolised, soils are found to be fairly uniformly pod- and soils at this stage are classif ed as sand zols (fig. 6).

"MEADOW SOILS"

Soils derived from alluvium are of minor import- Such ance on the Chathams. alluvial material as from peat-covered does reach the lowlands the up- land is deposited in an environment with a high positions it water table, in where either rapidly develops a peaty surface or is encroached upon by wandering dune sands. Alluvial material is accumu- peat develop- lating fast enough to keep ahead of ment and sand encroachment only over a total area have high of 5,020 acres. Here the soils a water belong table and impeded drainage and thus to the gley) category of rneadow (or soils. The main in development of these soils covers 2,300 acres the been vicinity of Lake Huro and they have mapped as Huro soils. Also included in these meadow soils are the River estuarine deposits of the Alvainunga and . Whanga Lagoon. Here, around the shores of the Te Fiu. Is. Knirakau sand podzol near Chu

13 over an area of 2,720 acres, the water table is TABLE 1. Classified List of Soil Types on Chatham brackish Island, with Areas and the soils are often known as salty meadow soils or saline soils; they are rnapped under Area Classilication 31ap No. (Acres) the name Te Whanga.

RENaziNA AssocIATED Ponzonic AND Solts ("Limestone Soils") Ohuku sandy clay I 47() "ROCKY SOILS ON STEEP SLOPES" .. .. Knhapiri shelly sand .. .. 2 400 nony a Amma sw These are the soils of the steeplands and on Chat I iis and ham island are skeletal soils almost entirely re- Young stage stricted to the cliffs of the southern coast. They Kekerione sand, coded complex .. 3 4, 240 101 reel cover an area of some 2,330 acres and are mainly 4 5.340 I sand derived from basaltic rocks. .. .. Te One loamy sand over peat .. 4a 1,140 Te One loamv shallow sand over limestone .. . .. 45 00 Te One shallow loamv sand over schist 4c 1, 100 "LIMESTONE SOILS" To one shallow loamy sand over hasait 48 so Semimature stage Very small areas of dark grey black soils de- n,ase to Repunui loamy sand .. 5 Mature (sand podzol) rived from limestone are found mainly in the Central stage part liairakau sand (1 340 of the waist of the island. where small areas of .. . I’oozouc Soil-s FROM SenisT ("Schist limestone emerge through the dune sands or soils") peat blanket. These through the soils are classified Submature stage Rendzinas. Occurring I’ukeraki fine sandy loam 7 (i,480 as with the rendzinas are .. GRANuLAR I.opus Curs small areas of slightly podzolised limestone soils tho\v.v AND ANDEsITIC fuve ( Yolcanic leachmg. FROM showing the results of accelerated under Soils") forest, in Dracophymnn and, addition to this, in inunature stage ne many places the limestone exerts some influence £8411: bbu)>\ rolling pha a peat over the sand and soils in the immediate Tiki hill brmen soils .. .. SH 1,470 The Tiki bmlyn clay. mottled phase Nb 950 vicinity of the outcrop. rendzinas and their Tiki reddish brown clay Sc 480 associated podzohc. soils. cover only 930 acres. Sandy Tiki brown hill 120 reddish soils .. NCH soils that show limestone influence cover a further semimature stage 60 acres. The areas of peat influenced by adjoining Alangabu clay loom .. .. 0 4.370 Alangahu clay loom, strongly rolling limestone were not mapped separately and would no phase . . .. On probably, less Alangahn hill on in aggregate, amount to than 40 soils . . 0,330 Submature stage RCFCS Tuku silty clay Inam .. .. 10 5, 260 Tuku hill soils .. .. InH 40 HRolvN GRANULAR CLAYS 13ASALTIC FROM ROCKS ( Volcanic SOils ) Frorn the foregoing account it can be seen that Immature stage pattern Rangitibi hill soils 11 no the broad of the soils on Chatham Island is . .. Semimature stage relatively simple. The landscape is more than half 1-inkopoi hill soils .. 12 420 occupied by organic soils, and, where the land is Hokopoi- lukucomplex .. .. It 430 not blanketed by peat, it has been to a considerable GREY Sons ("Aleadoly Soils ) del lay a extent covered by windblown sand. Thus between < pincers movement operating are grey peaty so the through the clay and clay loom .. Ish growth peat of and spread of sand, relatively little occasic sons ("I’eut and Peat soils ) is seen of the soils derived from the country rock. I’ateriki peaty sandy loom and loomy peat 14 3.010 Usually these are confined to a narrow strip. be- .. . .. Hapupu sandy peat . .. In 1,420 coastal sand inland bogs or is n,100 tiveen the and the to lataraepeatyloam .. .. bold headlands and isolated hills standing above la analy peat 4 general the level of the landscape. Although not of \wainunga peat in 0.000 great ...... extent these soils derived from the country Rekohu Awainunga complex .. 20 9,550 rocks are of great agricultural importance. The S^use son s ("Salty leadow soils ) general pattern Te whanga peaty loom El 2,720 soil of the island may show only a .. .. on few points of similarity with geological pattern, ""’1’’ the i s 1 yet an understanding of geological factors in the Asyntapu steepland soils .. .. de 2.330

14 pattern be develop- soil formation is of considerable importance to soil appears to closely tied to a in plant This is phenom- agricultural development. This is amplified on ment sequence the cover. a parts pp. 16-2n. enon quite common in other of New Zealand Another point which receives more attention in (Wright 1951a) but in the Chathams a somewhat following is in different mechanism seems be at work. the sections the manner which the to

15 FACTORS CONCERNED IN THE DEVELOPMENT OF THE SOIL PATTERN

pattern pherson Knowledge of the components of the soil (Macpherson and Hughson 1943), and in permits correlations with related soil types for 1957 the New Zealand Geological Survey under- geological which a successful pattern of development has been took a more thorough examination of the worked out elsewhere. It also permits local experi- islands (Hay et ed. 1957, unpublished). The general- proceed prepared mental work to on a logical basis, which is isect geological map (fig. 7) has been from essential for a reliable extension service to farmers. data provided by Messrs Hay and Mutch, and Dr pattern This knowledge of the soil is a potent factor Watters of the Geological Survey. initial development in the successful of an un- The oldest rocks are schists. These are considered developed or underdeveloped region, but to main- by Marshall and Benson (reported by Allan, 1925) progress it is necessary lithologically Central tain often to understand the to be similar to the schists of forces for strengths of the natural responsible the Otago, and probably Paleozoic in age. These rocks formation different pattern. of the soils in the soil contribute little to the landscape for they are always This pattern have understanding of the soil can of low relief, cropping out mainly along the northern considerable bearing upon long-range plans for coastline (fig. 8) and nearly always partly covered development. agricultural and silvicultural with peat or blown sand. Their highest outcrop is The factors formation in of soil are five number, at 140 ft above sea level (Port Hutt and Kaingaroa). provides There is the rock, which weathers and The rock is a quartzo-feldspathic schist, which parent material for soil; the climate, which in- produces a large amount of quartz sand on weather- processes; fluences the rate of weathering and of soil ing. The schists of the northern coastline are pro- processes; the vegetation, which conditions the ably the chief source of the quartz sand that land, determines the slope of the which often the sustains the beaches and dune areas. These latter intensity processes; interval grains of the and the time are composed of medium to coarse of white processes over which the formation have been sand, possibly of value for glass manufacture. operating. By studying results of soil formation the The soils clerivecl from this schist are always but five under conditions where all one of the sandy. Brown sancly clays are found only near the factors held less are more or constant, the relative shore under coastal scrub, but the common profile importance forces be of the natural engaged can is a pale grey to pinkish white fine sandy loam. The evaluated- latter soil has a strongly cemented subsoil, above Tivo soil-forming factors in Chathams of the the which, on flattish topography, rain water becomes obviously play only a in peaty will rninor role these perched and leads to the cleveloprnent of a studies: which is almost everywhere Most derived from topography, topsoil. of the soils schist are and interval, is about genesis subdued, the time which now buried beneath a peat blanket, and soil same over all parts of island. The the the oldest studies are restricted to a narrow strip between land surfaces are buried under peat, and best the the sea and the inland bog. They show that soils is derived available age range obtained on soils from quartz-rich parent materials are easily pod- from The factors coastal sand. other three of soil zolised under Chatham conditions, and that, even formation geology (rock), climate, and plant is -- under coastal broadleaved forest, the soil often (with its fauna) described cover associated - are developed to a submature stage. A slightly more below. advanced profile is found under Dracophyllum forest. Although profiles representing three stages GEOLOGY of soil formation were recognised in the field, only The geological Chathams submature stage is shown on soil map. tirst observations in the the the by Dieffenbach One best The by were made (1841). of the schists are overlain various sedimentary early descriptions of Chatham Island landscape is beds including limestones and calcareous tuffs of given limestone by Allan (1929), who also published a note on Tertiary age. The most conspicuous of the geology group Eocene the of the (1925). A comparatively deposits is a bryozoan limestone of age geological fairly recent examination was made by Mac- (Marwick 1928), found usually as a soft rock,

16 places pure: hard, grey, pitted, in renutrkably 9 to 991, according crops are a much slightly silici- o Ousev Whare- Hed In brown to commercial analyses held by Mr of rock. this area, soils are mostly clays places, immediate kauri Station (pers. comm. 1955). In surne formed from basic tuff, but in the large dark grey and this rock contains a admixture of volcanic ash vicinity of the outcrop the soils are and in other places is markedly enriched in quartz very sandy. Similarly, where dune sands are drifted higher sand. Although there are almost continouus ex- shallowly over a limestone outcrop, the posures broadleaved forest litter of this limestone in the low cliffs along the calcium content of the level in western side of the Te Whanga Lagoon, it is only a raises the of exchangeable calcium the soil minor soil-forming parent material. The main out- and, in some way, this appears to be associated with crops of limestone are to be found in the central abnormal melanisation (darkening) of the topsoil. portion of the "waist", three miles north of Te One, Yolcanic rocks occur in the north-ivest and the dark grey loams brown island. The group is con- where the soils are sandy on south of the northern depth in. from belong later period act- sandy clays ivith an average of lu the sidered to to a of volcanic limestone. Near Lake ivity group et al. 1957, surface to the underlying than the southern (Hay Huro and Waitangi township the limestone out- unpublished). The northern group are basalts

176 30 176 15 176 45

I -- -

I

DUNE SANDS ALLUVIUM ETC.

BEDS BASIC TUFF. BASIC VOLCANIC ASH - AND ASSOCIATED VOLCANIC ROCKS

BASALTIC ROCKS

476 IS 176 45 176 30

Fig. 7. Generalised geological map of Chatham Island

17 particles intruded into loosely consolidated tuffs and are derived from the weathering and fretting 500 ft The fossil faunas in beds in face. about thick. some of the of the exposed the cliff period tuff beds indicate deposition in the Pliocene The cliff sequences also disclose several old (loc. cit.). The southern group may possibly be swamp horizons, sorne still showing logs and Cretaceous in age (loc. cit.). The beds are upivard of stumps of a former forest. Some of the timber 1,000 ft in interbedded basalt be podocarp possibly Podo- thickness, mainly appears to that of a - Holys, tuff, and ash heels. These are well seen in the carfus halli. give cliffs along the southern coast, where they rise Hard volcanic rocks play a smaller part in soil rnain area of skeletal soils on Chatham Island- to the formation than the softer basic tuff beds, but both The beds give softer tuff and ash are soil-forming over rise to bright brown clays with well developed a fairly wide area. Soils from these rocks occur small aggregates in their early stages of develop- around the south coast from Waitangi township to ment. In the later stages of development, greyish- Oivenga; between Te Matarae Waitangi grey predominate and town- brown and colours and the aggre- Yellow Bluff; flanks gation ship; at and on the of many of of the soil is less noticeable, hills in the cone-shaped the north-west corner of the Marwick (Allan 1920, p. 292) noted beds of island. On southern is little grits the tableland, there shallow-ivater sands and lying unconformably peat partly doubt that the blanket is resting on limestone. These on the bryozoan are now con- beds. The of uniform tuff tuffaceous rocks are not sidered to be of Pleistocene age. Similar beds also Some layers are slightly calcareous, composition. occur resting on the tuffs of the later volcanics near contain quartz sand, fine pumice, give some and even Waitangi West. These beds rise to patches of other layers appear be less basic (i.e., while to con- gravelly sand of very low fertility. They are mainly fewer ferro-magnesian peat tain minerals) than the rest. buried beneath the blanket, but limited as Each variation gives rise slightly different soils. to are their exposures, they yet might become a 13ut since variations are often very local the these source of rowl metal when road Construction features cannot be adequately expressed on the in island. commences the north of the reconnaissance soil rnap. In general, the soils Macpherson (Macpherson and Hughson, 1943) from derived basic tuff tend to resemble the older describes beds of consolidated sands underlying the volcanic ash soils of the Waikato (Grange et al. peat at Owenga and Kaingaroa. These beds crop 1939). The resemblance is particularly close in the out again between Kaingaron and Wharekauri, and vicinity of the cliffs of Point Weeding, where cliff near Te One. They are consolidated dune sands, erosion has exposed an extensive sequence of with shallow-water bedding features. In places they sediments. The beds are prominently banded, as form a low peneplain, which stands at 180 ft above if derived from alternating showers of ejecta and the present sea level. Yet another level occurs at slow accumulation of ash. The soils at the top of present about 65 ft above the sea level. These sands derived from deep bed fine basic the cliff are a of peat are blanketed with over most of their extent, be material, which appears to equivalent to loess places but in a few near the coast, or on the sides have been built from and may up up-sivept ash peat of streams where the has been destroyed by fire or trampling of livestock, it can be seen that podZolised. the upper 2 ft of sand is strongly The soil profile is that of a sand podzol with a cemented, humus-impregnated layer in the sub- soil, which has the local name of coffee-rock. The sand podzols of the current-bedded sands are much podzols okler than the sand of the consolidated aeolian sands developed under Dracophy//unt forest in comparatively recent times, and it seems likely that the territory of the older sand podzols has long been buried under a blanket of peat so that they are not the result of contemporary soil processes. Phat they have changed so little in period appearance during their buried under peat prior may be due to the leaching of iron, mangan- ese, etc., from the topso0 and deposition in the Fig. 8. Quartzo-feldspathic schist exposed on coast at before Ocean Bay subsoil, where cementation occurred the

18 Where present, mineralised horizon forms a soil was subjected to reducing conditions under the this permits fairly peat. Brm "crust", which the use of heavy freely machinery and allows cattle to move without The older w ater-bedded sands appear to lx. bogging. There are usually tivo or three older quartz sands similar in composition to the dune horizons lower down in deep peat and forming The podzolisecl shower the sands still around the coast. probably these all add a measure of stability to the stages of the consolidated dune sands are far more bog. These layer are usually not more podzols ash showers extensive than the sand of the exposed than 6 or 8 in. in thickness and they are traversed parts of the water-bedded sands, but on the soil by root and stem channels. Locally these layers map soils from both materials were mapped the peat are known as "corky" because they have at together. penetrated by one been roots whose channels pumiceous present time Heds of sand are on Chatham pores now somewhat resemble the found m. cork island. Pumiceous horizons are fairly common in Alvainunga peat seen the and the oldest material Macpherson (Macpherson and Hughson 1943) Ohgocene was amongst the uppermost beds of the . have has suggested that this. ash may been blown beds. In peat, last pumice shower tuff the the from mainland New Zealand during periods of is 10 in, below horizon sometimes only 12 to the intense volcanic activity. Some of the older layers present soil surface, where it forms a compact of pumiceous material may, however, prove to be minerahsed. horizon of utmost value farmers. the to of much more local origin. The crater-shaped Lake bands Ifuro lies near the region where the ash are Petre Hanson deepest, and the twin arcs of and Hays suggest a line of collapsed craters. Indeed, in Waitangi the cliffs to the west of township there is a marked succession of coarse and fine breceia in the tuff sequence, which strongly suggests proximity to an explosive vent. * :; In many places there are large stones and . boulders of pumice of recent origin lying in the swamps and amongst the dune sands, often a mile Mr G. Wisner or more inland from the coast. of the Kaingaroa Peninsula (pers. comm. 1955) remembers pumice an occasion in 1918 when some of this was carried ashore by a very large wave at a time when Chathams was reported by the sea to the east of the lumps floating fishermen to be covered with of punuce. present, There are no hot springs on the Island at Maori place but some old NIoriori and names (e.g., Te Whanga "Waikato" on the shore of Lagoon) would imply that hot springs did exist in the historical past. geology in I’his review- of the relation to soil points The first formation brings out two clearly. intensity soils are changing. concerns the with which find quartz- It is not unusual in New Zealand to that rich parent materials are either podzolised or rapidly changing towards that condition as soon as they find become stable, but it is surprising to that producing basaltic rocks and basic tuffs are soils podzolised that are being comparatively rapidly lower content of parent despite the much silica their Fig. 9. Ash banding in A vainunga peat near Kaingaroa. This indicates some factor, or factors, L ppermost horizon consists of ash remaining after material. that peat fire; lower pale horizon "corky promoting intense an old with a in the environment is relatively appearance consists mainly of volcanic ash leaching.. It is important to identify the cause of this materials because if it is still under farming Most operative con- rain comes with the south-west ivind, usually ditions it will have a considerable influence on fert- as a quick succession of ice-cold showers of short practices iliser and other agricultural operations. duration followed by an interval of strong wind The point presence ground second concerns the of recent without rain. When the is dry, much of the layers in peats. Not volcanic ash the only do these rain from the brief showers is evaporated in the ivincl layers peats for make the semi-stable the operation before the next shower arrives, and the soil is but addition of In local of machinery, the volcanic-ash min- \vetted only superficially. opinion, the most provide erals may additional copper, a trace element useful rains are those that come with the north- provided that normally has to be in supplementary east and north winds. These are much warmer and peat form on many soils on the mainland. steadier rains, which promote rapid growth of pasture. Waitangi township is the only place with an adequate sequence of meteorological records and CLIMATE unfortunately there are no measurements to check The most complete appraisal of the Chatham the local opinion that the southern tableland does peninsula island climate is given in an unpublished pEunphlet receive more rain, and the north-east less rain, fallsin Waitangi itself. The of the New Zealand Meteorological Office (1947). In than township only mineral soils on southern this the climate is effectively summed up as "windy, the tableland are those formed from basic basaltic damp, and cool". tuff and rocks in sloping blanket peat has South-west winds predominate (frequency 30%) situations where a of been unable blow form. A comparison between and often for more than a week at a time, to these soils and those formed from reaching gale force on an average of 17 days in a similar rocks on comparable slopes in island does indicate year. North-west winds are fairly common in sum- the north of the that the soils mer, autumn, and spring, while south and south- of the southern area are somewhat more strongly leached. However, it must also be remembered east winds are more common in the winter months. that latter by geologists Calm weather is also most likely to occur in winter, the are considered the to belong different (and period The skies are frequently overcast: the average to a older) of volcanic activity. amount of cloud is To and clear days occur only 65 The sum total of the available evidence is incon- year but it is fairly days a on an average. clusive, certain that the range in is great. The mean annual rainfall usually ranges between mean annual rainfall not An approximate distribution 20 and 40 in., with an average of 33-6 in. recorded mean annual of rainfall is suggested in gauge Eg. 10. in the at Waitangi township. Outstandingly years 60 in, Waitangi Rain days (when 0-01 in. falls) ivet may exceed at township, or more amount to years year while very dry seldom show less than 20 in. 183 in an average and ivet days (0-1 in. or 80 per year. Even more) amount to only on the wettest days, rainfall rarely exceeds 3 in, and periods of 15 or more consecutive days with 0-01 in. rain ("rainy spells") are uncommon (only 25 in 62 years). Rainy spells are most likely to occur in winter.

Absolute droughts (less than 0-01 in. on each of 15 or more consecutive days) are much more com- mon than rainy spells (50 in 62 years) and in excep- [ UNDER 40 INCHES last for tiOnal CRSes may more than a month. Dry SO 40- INCHES (LC.,. leSs SpellS than 0-04 ln. On each of at least 15 tes OVER SO INCHEs be consecutive days) can expected to occur almost year every and may occur two or even three times in a single year. Dry spells sometimes last for more than a month. Hail is not uncommon, but snow is brief duration. Frosts rare and of very occur on an per average of only once year and are usually only very light. Air have temperatures a mean annual value of 51-60 45-40 F, the July average being 8 and Fig 10. Approximate mean annum rainfall on the Chatham island january average being 57-60 F. The mean daily

20 for year y is as (mean value 51-6" F) combine range is 10-4, _ which almost the same the temperature inHuence of a relatively low rainfall mean annual range. The highest and lowest air to outweigh the precipitation frequency 76’ 280 (mean annual 33 in.) and of temperatures ever recorded are F and F dry (one a year) in creating an respectively. spells to three times favourable accumulation of Humidity is high, having a mean daily value of environment very to the quite This may be so, but it is also 873;, at 8.30 a.rn and falling slightly throughout the organic residues. high p.m. possible that there may be unusually amounts day to SU$;, at 2 in rainfall and a usually large The foregoing information reveals an unex- of cyclic salt the deposited vegetation pectedly high frequency of dry spells, a feature of amount of oceanic salt on the factor may have con- is in resulting in a salinity that the climate that not expressed very clearly the bearing peat formation in the soil pattern.* siderable on pattern Chathams. The chief feature of the soil - wide- perhaps It many years ago by Praegar spread development of peat is not ad- was suggested - peat bogs foregoing infor- (pers. comm. 1933) that the of western equately explained by the climatic part frequent freland and Scotland owed some of their mation for it involves the assumption that Atlantic Ocean. fo), high origin salt-laden winds from the cloud cover (mean coverage moderately to peat bogs and deeply accu- humidity (mean value 878(,), and relatively low air Extensive ombrogenous mulating forest litters are features of the landscape subsoil features . *A fair soil prolles ivith compact ninttled in the Falkland Islands (Darwin 1980), and m the yellme-grey earths of south Otwo recalling those of the 1900; Learny 1950, developed in sub-Antarctic islands (Aston (Wright et al. 190) were recorded in soils beds Waitangi The coastal regions of some of the tuff near township. unpublished) and the southern yellow-grey earths are characteristically developed under Wright Miller New Zealand (Wright 1901b; and climates with a fairly marked dry season (Hurst 1911)

Cape Pattison peat developed mer schistase sands on exposed headland near Fig. I1. Shallow layer of woody

21 1952). In places most of these the rainfall is higher litter samples from areas on the mainland with a in Chathams, but than the all are subjected to a somewhat similar climate. The litter samples sub- high incidence of salt-laden winds. mitted included several from the broadleaved The possibility deposition forests that of oceanic salt coastal and others from the Dracophy//um play important part forests interior. may an in retarding the decom- of the position it is particularly of organic residues is a matter that requires surprising to find forest litter investigation. Mattson further et al. (1944, 1954) accumulating strongly under the broadleaved have studied the geochemistry of a single raised bog forest. Under the very high rainfall of Fiordiand part played in. per in Sweden to determine the by cyclic (approx. 200 annum), certain thick-leaved salt in soil formation, and Gibbs (1953) has des- broadleaved species (e.g., Griselinia sp.) form a places forest peat cribed the effects of cyclic salt at several on (Wright and Miller 1952), but on the the New Zealand mainland. Unfortunately there are Chathams, with a much lighter rainfall, a very high proportion no comparable data available for the Chathams. of broacl1eaved trees contribute to Handley (1954) has shown that sodium chloride the building up of forest peat. The karaka tree precipitates protein in fresh leaves, is extracts of and (Corynocarpus laevigatus) almost the only common proteins promptly. that stabilised leaf are relatively resistant tree whose litter is broken down Of the to decomposition. other common trees, huntil Olearia tray- .Senecio One ersii, Suttonia australis, and Corokia are conspicuous feature of the Chathams land- macrocarpa for litter scape is the development of small beds of peat on all conspicuous the slow rate at which their disappears. At in almost every one of the low windswept rocky head_ the other end of the scale, the Dracophy//um forests, is lands, in situations that are continuously swept by there a remarkable accumu- lation litter, from spray during rough weather. The plant cover is of mainly Dracophyllum arboream fern. The litter usually windswept scrub or low, twisted, forest trees and various species of tree analyses quoted in 5 in with a very high proportion of New Zealand flax table the appendix show that the salt broadleaved litter (Phormium) in the vegetation. These peat beds (fig. content of the under coastal forest is high 10 11) consist of bright reddish-brown residues, often - of the order of rnilligram equival- per fibrous and "woody", resting on rock or on a layer ents cent. This factors of sand overlying rock. The plant cover is period review of the climatic in relation to formation points. The icallydestroyedduringheavygales,andtheexposed soil brings out two first

surface of the peat usually suffers considerable concerns the need to consider some unreported plant factor, possibly blown inland from wind erosion before the cover can re-establish salt the sea, as for itself. In dry weather, bare peat surfaces frequently an explanation the slow breakdown of organic residues Chathams. The point carry a thick efflorescence of salt crystals, and it on the second con- peat cerns potential importance peat blanket seems likely that the beds themselves are the of the Chatham island farming. It is present directly associated with retarded decomposition of to true, at the farms is organic residues in a highly saline environment, time, that the carrying capacity of most limited in winter not so much by low Salt efflorescence can also be found on the litter temperatures as by lack of effective soil moisture. Under these under coastal forest. Many’of- the characteristic conditions, mantle of peat with its high storage broadleaved species have tomentose foliage (e.g., the great capacity for rain water shows up to advantage Olearia sp., Corohia sp.), and salt crystals can be parched in comparison with the cracked and clearly seen amongst the fine hairs on the underside growing volcanic clays and free-draining sands. Grasses, of leaves. The uppermost layer of the litter such as Yorkshire fog, are a fairly reliable source of accumulating under the coastal forest is frequently peaty extra stock feed on moorlands during the slimy and when squeezed in the hand exudes a the The farmers Chathams parts ciry winter months. of the black liquid. In other of New Zealand, the should be able exploit more effectively litter from broadleaved trees is characteristicalli, to this peat by judicious lime in insects attribute of the the use of rich and even small earthworms. In the. and fertiliser, and not be tempted burn away Chatham litters these are seldom in evidence. Dr to the organic layers and expose the barren mineral soil R. K. Dell of the Dominion Museum has examined a below. number of litter samples collected in the course of the soil survey and he reports (pers. comm. 1958) FLORA AND FAUNA that the invertebrate faunas extracted from the particularly litters were poor both in numbers of The plant cover of the Chatham Islands has species and numbers of specimens, compared with attracted the attention of botanists since 1860 (von

22 in years of high degree was destroyed so rapidly the early Mueller 1864) on account of the of several decades before there was any endemism shown in flora. One of the earliest settlement, the grazing. plant is use peat land for extensive ecological accounts of the cover that of move to the day, much of Draco- Cockayne (1901). Even in Cockayne’s the phyllum-dominated forest had been burnt. He des- In comparison with mainland New Zealand, the Podocar- remnants of Dracophyllum arboreunt rnost striking feature is the absence of cribes typical forest name "Tableland Forest". Rem- paceae, Dacrydiaceae, and such common mainland under the grass- of Tableland Forest still show the dum- communities as manuka scrub and tussock nants the inance Dracophy//mn. Associated with Draco- land. On Chathams it would appear one of the that phylum became arboream are many tree ferns (particularly single species arboream the -Dracophyllum -- Senecio Dicksonia squarrosa and D. fibrosa), hunt#, dominant plant of habitats that, on the mainland, Coprosma Hebe gigantea, Olearia semi- would have been occupied by podocarp-broadleaved chathamica, grassland. Corokia macrocarpa, Pseudopanax chatham- forest, manuka scrub land, or tussock clentata, peat in icum, Most of are builders Supporting evidence is found in the accounts of etc. these trees botanical of Chatham Island environment but none so early botanists, in the composition the Under in outstanding as Dracophyllum arboream. the small relict forests on the uplands, and wide- latter it is quite common to find a small spread occurrence of Dracophyllum roots through- tree, grass-like leaf litter, if Draco- bogs Chat- haystack of and, the out the peat. Indeed, the raised of the phylum whole be formed from Draco- form a complete canopy, the hams appear to mainly trees pl is usually soft and spongy with decomposing yllum residues rather than the moss residues area ft. Hugh- leaves and to a depth of over 3 suggested by Macpherson (Macpherson and tivigs quite possible son 1943), and it is that more than Dracophyllunt half the island was covered in dense forest early in historical times. In the early days Europeans, of settlement by movement across the forest. Areas per- land was greatly hampered by mitting comparatively free travelling conditions were known locally as "clears" and were differ- entiated as fern clears and swampy clears, the former being all-iveather routes and the latter being only in summer. The term is still in use negotiable , , forest has although most of the vanished, and the fern island is one big system of and swampy denotes areas clears - the expression currently recently burned, where the vegetation is short.

No explanation can be advanced for the absence from Chat- of members of the Podocarpaceae the hams. The presence of what appears to be Podo- buried Pliocene carpus sp. timber in the sivamps group have disappeared suggests that this may peat beds Chathams since that time. The of the pollen would provide excellent material for studies determine botanical history of to something of the group. the hand, is mystery as the On the other there no to disappearance former Draco- cause of the of the phyllant forests. The wood of both D. arborrum and * s , D. paludosuin is highly resinous and burns strongly litter is even when damp. The thick layer of also easily ignited, especially during temporary rainless & 1 o\ o quick, hot fire, spells, and burns with a which peat Fires in Fig. 12. View across southern tableland showing spreads rapidly through the forest. started li ith Dracoptyllion forest usually far, and this travel leteddindosj@reme < < thisoildW forest may explam why so large an extent of the forest in the foreground

23 Examination burning grazing, of the existing remnants of this continued and eventually to a forest it low fern-heath type of shows that is tolerant of a wide community with such species as range of moisture conditions. On the southern Leucopogon richei, Libertia ixioides, and Pimelea present uplands, where most of the relict forests are to be arenaria in relative abundance. In de- found, Dracophyllum arboreum trees 20 to 30 ft pressions (many of which were also occupied by paludosum high seem equally tolerant of the wet depressions Dracophyllum bog forest), rush, sedge, and the drier ridges. It is one tree that seems and sphagnum rnoss communities were developed. adapted to all parts of the peat blanket (fig. I2). These are maintained more by grazing than by Several of the other plant communities described burning, and when livestock and fire are excluded, plant by Cockayne are derivatives of the original Draco- even briefly, the cover becornes a low scrub- phyllum bog forest. On exposed places on the land dominated by Olearia semidentata and Draco- fire, phythan paludosum uplands, swept frequently by wind and the and eventually returns to plant cover that developed after destruction of the Dracophyllum forest. The soils confirm the botanical dominated by Cya- following forest is a heath community evidence that, the destruction of the leads Tableland Forest, thodes robusta. In tirne, repeated burning to original ecological conditions on by become drier depressions increased invasion bracken fern and, under ridges while in the table-

176045 376030 176015’

BROAOLEAVED

BROADLEAVED/DRACOPHYLLUM TRANSITION FOREST 1 -

DRACOPHYLLUM FOREST

RUSH SEDGE AND LOWLAND SWAMP FOREST

MARINE MARSH

COASTAL SHRUB AND GRASSLAND

Fig. 13. Approximate pattern in prehistoric Clutthani islamI of vegetation times on

24 land become grazing years process wetter. Continued burning and occurs in both cases, in recent the Cockayne has accentuate these tendencies. (1901) been hastened by the introduction of opossums. describes two types of heath community and three The non-forested lowland swamp communities forest by Cockayne successive stages of regenerating bog leading referred to are comparatively un- to the re-establishment of Tableland Forest. changed, but most of the forested lowland swamps plant Some of the other communities described have been deforested and are now replaced by by Cockayne have practically disappeared, notably rushes, sedges, and ferns (mainly Gleichenia sp.). the seashore communities and lowland forests. The salt meadows and lagoon-shore plant com- "Limestone forest" and "forested dune" commun- munities are largely unchanged. ities isolated Out five factors formation, it is are now restricted to very small of the of soil the patches. pattern Cattle are responsible for the initial of the vegetation (fig. 13) that fits closest damage, leading pattern. This be which starts a chain reaction to with the soil would, of course, ex- pected the disappearance of the broadleaved forests. The of an area where 590/, of the soils are derived damage by chief clone livestock is the destruction from organic residues, but there are a number of young low points of saplings and bushes and the suppress- finer of correlation that would repay study ion of new seedlings. As the forest becomes more in detail. damage increases damaged pity open, wind and the trees It is a that destruction of the indigenous by boring insects. Groups forest Chathams been for are readily attacked of on the has so complete, dead dying by gales formerly in- and trees are overturned the the soils suggest that there was an and before long the forest becomes a shambles of teresting zone of ecological tension between the rotting timber (fig. 14.1). At this stage some attempt Dracophyllum forest on the one hand, and the is usually made to clean up the area and encourage coastal broadleaved forest on the other hand. In pasture grasses, places, but if the underlying soil is sandy many and on soils derived from various pastures parent and not well consolidated the clie during materials, there appears to be a clear periods rainless and wind erosion starts to blow the sequence of soil development from immature to soil away (fig. 148). Sheep do less damage initially mature stages associated with a change from broad- greatest than cattle, but eventual destruction of the forest leaved to Dracophyllum forest. The zone of

la 111 fbin Mn. liamean.x 1 forested dunt (10 One has tal t mar \tensile crazing of unly suppressed regeneration forest becomes more open damage by and as the wind intra t ecological tension appears to lie in the strip of and, if valid, will also apply to some extent in the podzolised semimature soil where local patches of case of Dracophyllunt litter, although the socliurn developing influence in- litter is in soils are under the of content of the only about one-third that In forest litter 5, in dividual Dracophyllum trees. the soil, one can the coastal (see table Appendix). parallel read the progress of invading species with strong in many respects a can be drawn between pene- kauri Northland, New capacities for mor formation successfully the tree (Agathis australis) of trating a community whose dominant species have Zealand, and Dracophy//unt arboream in the The Chathams. Both large a weaker capacity for conditioning the soil. trees accumulate a rnound is both effect on the soil is well seen if an area of this sort of organic residues, condition strongly the pale grey podzolised patches processes bring podzolisa- ploughed - the stand soil-leaching and about greyish brown both become dominant out clearly against the brown and tion, and the species when podzolised patch The litter in soils of the background. Each the soils are sufficiently conditioned. leaf, coincides with an old Dracophyllum tree, and where the case of each species consists of twig, and highly the forest is dominated by Dracophyllum the whole bark residues of resinous composition. pale grey, podzolised has been area consists of soils. Beneath Reference already rnade to the corn- grey parative invertebrate fauna in litters the topsoil, the subsoil is commonly compact absence of the periodic pre- or cemented, and, as a result of the of Chatham Island. In the course of the soil survey sence of perched water, bog conditions readily it was remarked that very few earthworms were pits. develop. Whether on podzolised mineral soils or on found in the soil-inspection and sampling peats, be deep the Dracophylluns forest appears to Most of those seen were collected and were subse- growing quently identified by Mr K. E. Lee Soil fairly stable; to a large size, reproducing of the itself effectively, and living largely upon the plant Bureau as specimens of Allulobophora caliginose and nutrient return of its own litter. Eisenia rosea, both of which are European in origin Dracophyllenn accumulates litter at a truly and must have been introduced to the Chathams by arnazing rate. The possibility of an unusually high man They were collected from soil beneath rem- salt content in the Chatham environment influen- nants of broadleaved coastal forest in areas that are cing peat formation has already been discussed, lightly grazed by livestock.

grazing damage dune Fig. 148. Dying coastal forest near Taupoka: 1 inicr continued wind extends to soils unl screre erosion results

26 With paucity 36 regard to the of earthworms on thc "Tiventy-five species of rhizopods and species Chathams, Mr Lee comments as follows: of ciliates were recorded from the eight topsoil as well as nematodes, rotifers, "The earthworm fauna of Chatham Island is re- samples, tardigracles, present. collembola, enchytraeids, and an markable for the small number of species turbellarians, worm. Only three species of Megascolecidae, Diporochaeta aeolosomatid "The number of rhizopod and ciliate protozoan chathantensis, Rhododrilus huttoni, and Pontodrilus species found in each sample are detailed in table 2. matsushimensis var. chathamianus, and tivo species of Lumbricidae, Allolobophora caliginosa and Eisenia rosea, are known (Benham 1901; Lee 1909). Litter TABLE 2. Number of Protozoan Species in Soil and Samples from Chatham Island " Pontodrilus matsushimensis var. chathamianus No. ricaozoan is a local variety of a species which lives on the sea odd shore and is widely distributed on Pacific islands. No. Type 1-lorizon pH Ithizopods Ciliates presence Chatham Island probably its on has 1 Alvainungapeat 4-8 20 19 .. .10 peat An 3-0 5 0 resulted from prolonged isolation of a colony which 2 Awainunga .. na unga peat A 3 0 4 could have reached the island by rafting. Diporo- chaeta chathamensis and Rhododrilus huttoni are 5 Pukeraki fine sandy loam A n-e 7 14 regarded as indigenous species with close relation- .. .. 6 Rapanut loamv sand A 5-5 1 L New Zealand They ships to species. are rather small 7 Te one loamy sand A 5-2 11 li species (D. chathamensis is ca. 50 mm long and R. 8 Tuku fine sandy loam A 4.0 a s huttoni ca. 100 mm long) and may be derived frorn .. .. forms were rafted or carried by sea birds protozoan fauna does which "Generally the not show from New Zealand." especially marked affinities with that in the soils of presence islands but does With regard to the of introduced species Stewart or the sub-Antarctic re- forests Mr Lee New Zealand invading native on the Chathams, semble that in comparable soils of the peat comments: mainland. Of the topsoil samples, that col- from Dracophy/bum forest (No.1) is "On the New Zealand mainland, lumbricids are lected tableland peat rarely found in forest unless is is extensively modi- somewhat less acid than the other three top- The latter fied by stock grazing, and indigenous Megascol- soils (Nos. 2, 3, and 4). represent secon- dary kinds peat developed under various kinds ecidae are dominant in forested soils. It seems likely of plant and modified by fre- that at Chatham Island the indigenous earthworm of cover maintained burning and grazing. The protozoan fauna of fauna is so reduced that no species are available to cluent peat is forest litter occupy some ecological niches and A. caliginosa has the forested typically a sample, fauna of other resembles the therefore been able to establish itself in forested whereas the the three peats New A position by Lee (1953) fauna in the lowland acid of mainland soils. comparable ivas noted at Raoul Island, where indigenous earthworms are Zealand. is broadleaved rare and Eisenia foetida (Fam. Lumbricidae) "The mineral topsoils under coastal common in forested soils. forest (Nos. 5, 6, and 7) have a fauna closely re- "The small number of indigenous soil-divelling sembling that of comparable mainland soils, and No. fern rough pasture, species known from Chatham Island, their close 8, collected under and faunal of strongly resemblance to mainland species, and their re- showed the typical characteristics podzolised islands leached and weakly topsoils on the stricted distribution within the indicate that fauna is probably of origin mainland." the earthworm recent and has probably been passively transported to I)r di Menna reports as follows: islands rather migrating over land con- isolated dominants from the than "Most of the veasts as generally nections, and that soil conditions are not Chatham Island samples were same as the soil the favourable for the activities of earthworms. The in New Zealand those from comparable sites the position is comparable found on Campbell fer- to that mainland. The exception was the undescribed 1sland (see discussion by Lee 1959)." Torolopsis from Alvai- inenting species of the eroded litter from Chatham Island peat. Physiologically is The soil and samples nunga this species com- by Dr D. Stout Zealand yeasts be were examined J. (New parable with the which seem to typical of Soil Bureau) for soil protozoa, and by Dr M. di low latitude, high altitude peats and does not re- Zealand Soil for yeasts. Menna (New Bureau) soil semble the non-fermenting, mucilaginous, nitrate- of lowland soils. Dr Stout reports as follows: using species temperate-climate

27 "The soil samples were up to three weeks old (Hamilton, in press), Stephens (Ward 1904), and yeast when cultured and changes in the flora had other off-shore islands of mainland New Zealand probably Numbers yeasts occurred on storage. of would be likely to leave traces of disturbance in the in soil usually lessen keeping. Qualitative profiles, in with soil especially those near the cliffs of the changes may occur also, but rather slowly. The southern tableland, but such traces were no longer for results the seven soils examined are set down in clearly visible in these soils. Large lizards appear to table 3. be absent from the Chatham group. Wekas, pukekos, and black swans largest birds "In comparison with figures from New Zealand are the on the island, and these are present in consider- soils, the counts were moderate to very high. three able numbers. The soil-disturbing activities of "Candida humicola (Daszewska) Diddens and the wekas and pukekos are mainly confined to Lodder is pectinolytic and probably concerned in scratching amongst the surface litter but, like the plant the initial breakdown of material; Candida swans, they also forage in the reed and rush swamps muscorum di Menna is proteolytic. The undescribect and pull apart the clumps of roots. The black swans species of Torulopsis may be able metabolise to are present in thousands on Te Whanga Lagoon and under anaerobic conditions, but Candida humicola, are responsible for a good deal of trampling on the Candide Candida curvata, and muscorum show no lake At great margin. nesting time they transl>ort a grow capacity to at reduced oxygen tensions." deal grass of sea (Zostera) ashore to build their is known Little of the larger fauna formerly conical nests - structures that may reach 2 ft in inhabiting Chatham Sea particu- the Islands. birds, height. After the breeding season, the old nesting petrels, larly are said to have been numerous on materials often become scattered about and form a Chatham Island but the soils show little sign of their valuable addition of organic matter to the thin, burrowing activities. Widespread petrel nesting shelly Kahupiri soils,

similar to that which can be studied on Raoul Native rats are said to be absent from the Island (Wright and Metson, in press), Little 13arrier Chathams.

TABLE 3. Yeasts in Soil and Litter Samples from Chatham Island

Number pH ofYeast When Yeasts Species Soil Yegetation Cultured per gram 1)ominant Yeast Present

Awainunga pout Oracophy//unt Inrest .. arboreunt 4-8 Candide hunticola (70’!!, of 4 .. isolates) pubdvsunt Awainunga pent /)racophyllant hop 3-ti 13,000 Candida curvata (70’};,) 4 forest Awainunga peat Hare (eroded: formerly 3-6 00,000 Fermenting Torolopsis ti Cyathodes) sp. (45’);,) Rekolm peat Cyathodes robusta heath 3-5 11,000 Candida curvata (an’};,) 4 Pukeraki fine sandy Alatipo forest 6-2 3,000,000 Candida muscurum loam

Hapanui loamy sand Karaka forest 5-5 100,000 Candida muscorant le One loomy sand Karaka/akenke forest 5-2 0.000 Candida curvata (30’);,) Candida hunticula (2 0), )

28 HISTORICAL FACTORS CAUSING MODIFICATION OF THE SOIL PATTERN

factors but it is likely A study of the environmental affecting approach the shore, not at all that the have be interested in soil formation on the Chathams would not be com- Moriori would reason to the plete peat for have been largely without a brief consideration of the modifying areas, these would live forest in his The influence of the men and animals who came to covered with Dracophyllum time. pressure inter-tribal Chathams on the island. of warfare on the Moriori Chat- great fortified in interior it is thought that the came to the was not so that areas the hams in about 1.0. 900 and that they either arrived were regarded as a necessity: a constant struggle without viable food crops (such as kumara) or were with nature to ensure adequate food supply would propagate unable to them on arrival (Smith 1911). occupy much of their time. few food gardens in The Chatham Islands be in New There are but signs of old the must unique Moriori place Maori sandy soils where the early settlements were Zealand as the only where settlement place established and, perhaps for food supplies other took after European settlers were already fern karaka berries, have One is than roots and they may established (Shand 1892). result of this that practices depended mainly upon fowling and fishing. The few specifically Maori have left their mark karaka tree is claimed by Richards (1952) to be a in the soil. At the time of the arrival of the Maori, pre-European introduction from Tauranga on the cropping, grazing, and burning were already a well- mainland of New Zealand, a claim that cannot established pattern of land use. readily be substantiated. The karaka tree un- The history of intensive land use began about groves grely doubtedly occurred in in the vicinity of 1840. Early settlers vegetables and even Moriori settlements, but it is also very widely cereals (wheat, oats, barley) for passing whalers and established throughout the whole of the coastal sealers, and for trade with Australia (Simpson forest on the Chathams, some of the trees being very 1950). This phase lasted from 1840 to about 1860 large. It is barely possible to understand holy the (Hunt 1866), by which time there had been con- present soil pattern could have evolved without siderable introduction of livestock (about 2,000 assuming that karaka has always been a constituent sheep, 1,500 cattle, and 500 horses) (Seed 1862). of coastal forest on the island. Initially, livestock did very well on the rough The need for some reliable source of starchy food forage obtained by burning the native vegetation, prompted may have the Moriori to attempt some and by 1865 several mainland farmers had become form of bracken-fern culture. The only soils suitable interested in leasing large blocks of land for sheep purchase for this would have been those in the zone of sandy runs. Only a few were able to land out- young soil between the lowland bogs and the dune right owing to the difficulty of determining land sands. This might supply an explanation for the un- titles. In time this difficulty was resolved, as by pastoral usually strong melanisation of the topsoil of the 1880 there were a number of holdings Moriori from Many sandy soils in the vicinity of some of the old ranging 5,000 acres to 20,000 acres. of European holdings settlement areas. Deep, thorough melanisation of the smaller and much of the prolonged land for this type is commonly associated with Maori leased was similarly used extensive occupation by bracken. Many of the old Moriori grazing. The majority of the large runs were oper- settlement areas are marked by very old shell ated by managers on behalf of absentee landowners. These have developed deep dark grey There is doubt fodder middens. a to some as to the nature of the profile but deeper in days. No black rendzina similar to, than, available to stock the early natural grasslands by the shell-midden soils commonly encountered on were reported the earliest visitors 1955), and list of native and endemic the mainland. (Madden the Macpherson (Macpherson and 1-lughson 1943) grasses given by Cockayne is not lengthy. Never- Moriori in it bog forest commented on the absence of artifacts theless, was something other than and pioneer the peat beds and suggested that this might indicate fern that attracted the attention of settlers. great peat bogs. It is There is likelihood the antiquity of the true that a strong that the most attractive there is scanty evidence of Moriori occupation to be feature of the Chathams in the early days of settle- found on or in the peat bogs, except where they ment was the broad sweep of land of gentle relief

29 low largely carrying a vegetation made up of native "clears" and sand-dune country, and wild cattle herbs grasses, found and such as can still be today were likewise numerous until a few years ago. forest have wherever stands of old Dracophylum Although relatively few feral livestock now remain, The pioneers pits been recently destroyed. were mis- the large number of abandoned once dug by in plant palving taken, however, assuming that this cover the feet of wild bulls roaring their challenge persist pastoral would under free-ranging farming. across the moorland testify to the former density Events soon showed their mistake. In the afternoon of the herds of wild cattle. Wild pigs are seldom R. Chudleigh, Whare- of 28 February 1888 E. of seen, but judging by the evidence of their rooting - kauri Station, returned from a ride around his mainly confined to the steep peat-covered slopes sheep and wrote in his diary: "I cannot tell what near streams draining the southern upland - there the sheep live on. There is no food to be seen on the are a great number living in the forest. Rabbits and home paddocks. Ferb run outside the everywhere. hares are not present and there is some doubt if What was grass in thousands of acres is now fern they were ever brought in. A move to introduce (Chudleigh 1950). That was 22 years after he had hares for coursing in the 1880s was vigorously dis- purchased property carefully selected and a that puted by a deputation of settlers who visited he considered to be representative of the best land Welhngton. especially secure a general ban on pioneers to on the island.. To this. day few have reahsed- Opossums. properties, activities of this sort (Chudleigh 1950). what really happened on their intro_ however, were introduced, and they have spread A large number of the horses and cattle damaged few duced in the early days escaped from supervision widely and seriously the remaining and existed thenceforth in a feral state. At one areas of coastal forest. Introduced rats and mice time large droves of wild horses roamed the are fairly common in settled districts.

30 PEDOLOGICAL SIGNIFICANCE OF THE SOIL PATTERN

petrological Thus, in Chathams, mineral-soil development For a small island the range of rock the early maturity marked by types is very wide: from rocks rich in ferro magne- trends strongly towards largely widespread peat formation. This trend is most sian minerals to rocks composed of silica; derived frorn quartz-rich parent frorn sediments with an abundance of calcium and rapid in the soils basic volcanic areas and the magnesium to sediments almost completely hicking materials, slower on the pattern limestone and is only resisted successfully in these elements. The soil shows that all country, parent fresh sand blowing inland sustains a measure these different kinds of material undergo where youthfulness in landscape. The organic soils, fairly rapid change and, in almost all cases, give rise of the prailes display so rnany of the mineral soils are now to a range of soil that successive under which development. In areas stages in a leaching sequence towards podzolisation. buried, also show rapid little disturbed by farming, raised bog Neither the climatic range, the range of stable relatively peats still growing, and topsoils consist mainly surfaces of different ages, nor the topographic range, are living plant raw plant remains. In considered singly or in combination, is adequate to of tissues and pattern. forest has been destroyed the vege- account for the main features in the soil On areas where the hand plant has become differentiated into heath on the other the composition of the cover tation the drying fern, and moss swamp- and the apparent ecological relationships of the ridges, and rush, parts pat- On ridges the topsoils component do match closely with the soil communities elsewhere. the of young heath residues accumulating on tern. The vegetation of the Chathams has almost consist partly humitied Dracophyllum peat, while in certainly been a very potent force in soil develop- the good deal sphagnum peat ment, and soil-plant interrelationships have been, swamp areas a of recent is be found. In localities where more intensive and still are, very close. to farming is attempted, oxidation and breakdown of in the Chathams the chief mechanism whereby peat has largely peat formation. Here soil changes are conditioned is the accumulation of the replaced formed frorn strongly oxidised organic residues, which, in the course of time, de- the soils are usually peat. decomposed and, when the grass cover is velop into a deep layer of acid There is the materials fair powdery may be possibility that sodium chloride derived from sea incomplete, a amount of soil promoting lost by As farming continues, and spray may be a factor in litter accumu- wind erosion. proceeds, lower in perhaps by oxidation of the surface layers the lation the initial stages, creating an play layers peat bog will come to an environment inimical to the invertebrate popula- of the original litter breakdown. increasing part in farm operations. tion usually associated with the Whatever reason, the soils are undoubtedly con- peat is the The present micropattern of the soils permits ditioned in a manner that the entry of largely the result of casual firmy. and uncontrolled species tolerant of a lower plant-nutrient status. and it is liable to change from time to played by Dracophylum crrazaw, The dominant role ar- land-use practices time, depending upon the to boremn over a range of conditions equally suited to which it is subjected.. Under sympathetic, skilful podocarp forest, manuka scrub land, and tussock farm management, it may prove possible to induce grassland, biological may be in the nature of a peat a measure of uniformity. in the soil over a accident, but has certain]\ resulted m. the wide-. greatly it hmited. area of bog land, which would deep forest peat. Draco- spread development of in phy//mn simpHly subsequent farming the area. arboremn appears to tolerate a wide. range The pattern has a penetrating agricultural of soil moisture and can survive with little apparent soil it has farmers difficulty in its signiticance for islanders: ruined on the mineral return own organic the Draco- financially in past and it can continue bring residues. The early entry of individual the to future. The phy//unt into broadleaved forest, hardship farmers in the section trees ahead of the to the follows discusses fully agricultural main advance, produces individual patches of soil that more the pattern form inherent in unusual soil of so strongly leached that they a conspicuous significance the Chathams. feature of the soil micropattern. the

31 AGRICULTURAL SIGNIFICANCE OF THE SOIL PATTERN

Under the natural coalitions of soil formation, soil, now doing duty as a topsoil, is almost without general pedological the trends are tolvarcls in- plant nutrients and, moreover, is usually strongly creasing acidity, lower plant-nutrient levels, and cemented and a most unhappy medium for the build-up of organic matter in the soil surface. This development of grass roots. In the past, farm land applies everywhere excepting only sites where that has reached this stage has been abandoned, blowing sand, accumulating stream alluvium, or and only in recent years have attempts been made provide the weathering of outcropping rock a to redevelop the areas through the use of fertilisers. general natural mechanism for holding the trend The organic soils are thus now in a condition far at bay. This means that farming in the simplest removed from that which originally attracted the way (i.e., with as little disturbance of natural con- pioneer sheep farmers. Only one farmer, and he possible) ditions as will normally have to contend only by exercising the greatest care (even to the with acidity of soil, low reserves of inorganic plant extent of hand planting areas with palatable native nutrients, and slow breakdown of fresh organic grasses), has managed to preserve a shadow of the residues. The main reserve of nutrients for plant original type of pastoral farming. This farmer has growth peaty process pasture is in the material, and any built up both his soil and his to a level that peat production that releases nutrients from the will naturally can support a low but sustained of promote plant growth. process The most effective wool without the aid of lime and fertiliser. This has peat, possible pasture is simply burning of the and, as the early been only through very careful pioneers discovered, the destruction of forests and management and by skilful application of the their associated litter layers by a good, hot fire principle of transferred fertility, whereby the fer- gave young a deep layer of ash, which contained ample tility of the sand soils was constantly trans- growth nutrients for the of succulent native herbs ferred in the sheep droppings and shared amongst grasses. The pastoral poorer and early activities of the the soils on the farm. There is no burning Chathams founded property. were on the fertility accumul- on this ated and concentrated in the topsoil by the burning Free-ranging pastoral farming has in general been When of the forest. this was exhausted, the sheep more successful on the mineral soils than on the invaded by bracken fern group In runs were and rushes; main of organic soils. the case of the herbs grasses gave broadleaved I native and way to unpalatable sandy soils near the coast, the original species, as described so feelingly by E. R. Chud- forest seems to have resisted wholesale destruction leigh in 1888 (Chudleigh 1900, p. 46). in the early clays more effectively than the resinous peat On the deep areas, repeated burning to Dracophyllum forests, and the subsequent slow palatable grazing maintain nutrients for a few piecemeal destruction of the broadleaved forest pastoral provided plants has been able to keep alive a type of has a constant succession of fresh areas industry with a low turnover. The burning is not of soil of comparatively high nutrient level. In at all efficient for it causes repeated destruction of some cases, a relatively small area of freshly devel- provides reserves, usually more available nutrients oped land with residual forest fertility in the soil pasture plants than the small communities of can has been employed to support the economy of a make use of, and either destroys fences or en- farming unit. However, this phase is drawing to a courages the use of unfenced rangeland to the close since there is no longer sufficient coastal point livestock be properly where cannot super- forest left to exploit in this way. percentages visecl. Lambing are low on the un- It is not widely realised that the total area of peaty fenced moorlands and the remains of animal naturally fertile soil, capable of carrying regularly carcases are to be seen everywhere. stock in excess of one sheep to the acre, amounts Where peat blanket is less for Chatham the shallow, repeated to than 500 acres the whole of burning soon brings to light the buried mineral island. For nearly three-quarters of a century, the point soils. From this onwards the farmer meets farm income of the island has been obtained a serious dificulty, for there is no longer any mainly by the exploitation of the slender reserves organic reserve of plant nutrients, and the mineral of soils that are not naturally fertile and would,

32 he in some Te One Ohuku soils. The latter would moreover, in the natural course of events, and gaining grow pasture losing rather than in fertility. be expected to copper-cleficient under Chatham more intensive farming. The appearance of copper, Almost all the soil types of Island re- perhaps deficiency peat quire plant nutrients in the form of fertilisers. On and cobalt, on the soils might depend a large measure on presence or some farms, fertilisers have been in use for a number to the absence of ash layers or other mineral horizons in of years, often with excellent results. On other peat is likely fertiliser has been disap the beds. Cobalt deficiency more to farms, the response to appear in livestock grazing improved pastures on pointing. Critical fertiliser trials conducted by the sandy soils. Department of Agriculture are urgently needed on the intensive farming information becomes In the long run, must replace the island. Until of this type put rangeland farming throughout the island indeed available, one can only forward estimates as to full is be probable fertiliser in it is necessary if advantage to taken of the the response to the case of each Since fertiliser based deduc fertilisers added to the soil. must soil type (see extended legend) upon Chathams data between inevitably cost more on the than on the tions from the soil and correlation the mainland, it is more ever necessary to avoid island soils and soils on the mainland of New than pasture waste by applying fertiliser only to mix- Zealand and elsewhere. tures that can respond to it. It should be noted that the amount of fertiliser Whether deep peats of the uplands can be needed annually to replace plant nutrients sold off the brought in and used for intensive farming is a lost by the farm in crops or livestock or normal cluestion that can be resolved only by careful ex- leaching may be much less than the appearance of periment. In many respects the Chatham peats are soil profile suggests. The rainfall over the the peat farmed in unlike the areas normally mainland Chathams is comparatively light, and the intense New Zealand. For instance, do not as a rule leaching produced strongly developed soil they that the period because, powerful require an initial of consolidation on profiles was due more conditioning by to Chathams, plant the there are usually one or more min- the natural cover the volume of rain than to present in peat, passing eral horizons the contributing water through the soil. Fertiliser trials ma\, greatly stability of soils. show apart from an initial heavy dressing of to the the that, pro- The soil pattern also suggests that once the lime on some soils, the best results come from com- blem of fertiliser suitable for each soil type has been paratively light but regular applications of re- ansivered,theproblemofachievingmaximumyields verted superphosphate or basic slag. will become one of provision of suitable supple- phosphorus prove It . likely that will. be the is to mentary winter feed and supplementary irrigation. element most needed for pastoral development in for some of the pasture during the summer or sea- the Chathams, with calcium. needed additionally. sonal dry spells. quite potash on a large number of soils,. and on a Guy, smaller group of soils. Of the minor or trace ele- *Available-copper determinations made by Mrs E. 11. g an Aspergillus assay technique ments needed by livestock, copper is almost cert- 2 lo nl li ainly to be needed on the sandy soils when intensive P.p.m. I farming on improved pastures becomes general on liairakau sand . .. - Rapunux loamv sand 6 present - these soils.. Available. soil. copper* under the one 3-4 Te loamy sand .. .. produce Ohuku 3-4 farming conditions is low enough to copper- sandy clay .. . .. n ua11<>n loamyT sand c)1er li sense : 6 deficient plant tissues in the case of Kairakau and

Rapunui soils, and is approaching critical level Tuku loam 4.0 the silty clay .. . ..

33

3 RELATIONSHIPS WITH SOILS OF THE NEW ZEALAND MAINLAND AND ELSEWHERE

One purposes of the main of the survey was to Close equivalents to Tuku and Mangahu soils are Chatham island correlate the soils with the soils of to be found on Chiloe Island in southern Chile (lat. New Zealand This has been the mainland. done, as 41. 52’ S, long. To 40’ W). One of the commonest far as possible, in the appendix, where an approxi- soil-parent materials on Chiloe Island is moderately has been given for mate correlation each soil type. basic ash derived from volcanoes on the nearby The mainland region showing the strongest soil mainland. Soils are developed in this material under island is correlation with the undoubtedly that of a climate closely comparable to that of the Chatham Southland South Otago. Many Islands. Over half coastal and close the western of the island, soil equivalents of the Chatham lowland peat and gley development has been strongly conditioned by peat- be found soils are to on the swampy flats between building forest dominated by taxads and Notho- Invercargill Otara; likewise and many of the Chat- fagus. Under Nothofagus forest (usually dominated ham soils derived from sand find by N. profile coastal their dombcyi) the soil resembles that of the Catlins closest counterparts along the coast from Mangahu soils, viz: Bluff Harbour to Pounawea. The upland peats and in. peat, their associated soils have no very close counterpart 4 Clark reddish t>rown fibrous 4 in. grevish brown somewhat peaty silty clay Icani, on the New Zealand mainland apart from minor 4 in. very pale brown silty clay loan almost areas on the summits of the Blue Mountains and on structureless, a in. k lwolivn faii other table mountain plateaus in southern Neil Tuatapere district. 2 in. very dark brown loamy peat, re utn silbt loani70ma The soils derived from basic tuff and basic vol-

canic ash are, within the New Zealand assemblage, in. dark (reddish) brown silty clay loam, slightly peculiar group. peaty. more or less to the Chatham On the 2 in, strong brown compact silty clay loom with New Zealand mainland, basic volcanic ash and basic ironstone concretions, beds in North Island, ycilowish brmen loam. tuff occur mainly the where on silty clay soils develop under a moderate to strong weathering Soils profile provisionally with. the above are named environment. The fiki and Mangahu soils. are thus Chiloe silt. loam only distant, moderately to weakly weathered rela- The Chiloe soil. series are mainly. developed in. Waikato derived from basic tives of soils. of the ash. lowland situations in the central and western parts becomes little fhe relationship a closer if. com- of Chiloe Island. Aerial. reconnaissance of the west- parison is drawn between the Mangahu soils. and ern uplands of Chiloe Island disclosed extensive patches less leached the of weathered, strongly soils areas of low shrubby forest and bog vegetation from basic ash occasionally found on the high mountain ranges of the North Islabd. So far no a n)an1cs we oe remisil< all adog ed tl e Clul soil equivalent to Tuku has been found on the New b5

Zealand mainland. des Resources Agricolas, Santiago, Chile.

34 land is and it would appear contiguous with the taxad forests, suggesting that now reverting to scrub, pass farmers Chiloe will, like counter- the Chiloe soils may under a thick blanket of that the of their parts Chathams, be forced peat in a manner similar to that which occurs with on the eventually to build level of soils by using Tuku soils on the Chathams. up the nutrient their Agricultural development has only recently fertilisers and lime. Chiloe Potatoes, The derived from schist likewise have no reached the fringe of the soils. oats, soils in New Zealand. and barley are grown for the first year or tivo, but, close counterpart mainland plant for Similar in Fiordland, but where they since the nutrients these crops come al- rocks occur are always most entirely from the organic residues left by the occur in landscapes of easy relief they pastoral peat. It is possible forest, there is usually an early switch to deeply covered with that the pro- farming (both sheep and cattle). An abundant schists of Chiloe Island (Darwin 1890) may supply of rough timber allows close fencing of the duce comparable soils on the south-western coast beds out, but post-and-rail type but even the most careful stock where the volcanic ash tend to thin by management seems unable to maintain a satis- no schist-derived soils were noted the author during Chiloe in 1954. factory closed sward for long. Much of the cleared a visit to

35 DEVELOPMENT POTENTIAL OF THE SOILS

pattern poorer From about 1890 to 1951 the land-use on On the soils (Rapunui, Kairakau, Man- Chatham island remained fairly constant. The gahu, Tuku, Pukeraki, Hokopoi, and practically number of holdings varied from 70 to just under all the organic soils) farmers will probably ex- grazing perience 100, the number of acres of land was more difficulty in establishing high- approximately 165,000 acres, and the number of producing pastures. The Tapuika and Awainunga generally peats probably sheep on the island was under 100,000 should be classed as problem soils, head. since there is only a very small amount of farming guide development experience available to the of In 1951 (according to the annual report of the high-producing pastures on these soils.. Until New Zealand Department of Island Territories) further facts can be gathered and a few careful there were seven absentee owners operating over field trials laid down, the Awainunga and I ,apulka. 73,400 acres carrying about one sheep to 2 acres; a soils. are best excluded from schemes for intensive further 91,000 acres (mamly. small hoklings under agricultural development. Although both Potus. 1,000 acres in extent, with. a few larger holdings. been planted radiata and macrocarpa trees have between 1,000 and 2,500 acres) carried. about one on these raised-peat areas, their. slow rate of growth sheep to the acre. Some of the farmers of the latter does not hold out rnuch promise for afforestation group were beginning to use fertibser,. sow clown schemes with. these species. Afforestation. would better grass-seed mixtures, and make more inten- probably be relatively. easy to undertake and sive use of better soils. on holdmgs.. Smce. the their preferable pasture on both Tuku gradually to the and 1951 tins. tendency has increased and Mangabu hill soils.. Apart from the last-mentioned many more of the small farmers as well as a few soils. and the raised-peat areas, the remainder of of large landowners have begun use fertiliser.. the to poorer the soils. in the category should be suitable On a few of smaller farms a carrying capacity of the for either. short rotation, long rotation, or perm- two sheep acre has been achieved.. In to three to the anent pastures of a relatively. high-producing population type. 1953 the sheep . was 127,000, spread over Establishing pastures will . discing-in full these involve 95 hoklings.. The idea. of makmg. use of the better the existing. cover of fern, heath or short Draco- class of soil. on each property has brought about a phyllum scrub; the use of lime, and of fertilisers noticable withdrawal. of stock from the poorer parts containmg sources of nitrogen, phosphate, and of the rangeland. There still remains a great deal to potash. Much of flat land (Pateriki, Hapupu farming the be done to raise the standard of on the ’ Matarae, and Mautere soils). will. require additional. Chathams lambing percentage for the the island. - drainage before development can proceed far. is, in some years, under 700/o - but the majority of Almost. all the soils. in this category require a great farmers moving in right direction.. . are the permit proper deal of additional. fencing to control grazing. The better soils of the Chathams (Ohuku, of Some of the best examples of develop- poor Kekerione, Te One, Tiki, liangitibi, and Huro) will ment on soils were seen at Wharekauri Station, grown present little real diHiculty to a farmer intent upon where fodder crops were using fertiliser for pasture, years pastures establishing high-producing whether for several before the new were sown fat-lamb raising, for dairying, for beef cattle, or down. production. wool In most cases closer subdivision The saline soils (Te Whanga soils) and the grazing of the areas and improved water supplies Kabupiri shelly sands are best kept for rough prelude grazing for livestock are a necessary to improved until the water table of the Tc Whango pasture establishment. The key fertiliser is likely to Lagoon can be brought under control. A compre- be phosphate, and, with its aid, profitable short- hensive impoldering and drainage scheme for the rotation pastures should be easily maintained. On Te Whanga Lagoon would be quite feasible and Kekerione soils the aim should be permanent would make available a considerable area of fertile pasture because these soils erode rapidly if land for additional farm settlement. The Awatapu ploughed. On Huro soils, preliminary drainage of soils on the steep cliff faces should be treated as the area is necessary. forest reserve.

36 10 of original Tableland Additional small forest reserves are needed to than square miles the is preserve examples of the original Chatham plant Forest now remains, and this relict shrinking passing year, cover for future biological studies. In many respects with every Chatham provides peculiar bio- The better agricultural soils of Chatham Island the environment divided into logical conditions that certainly warrant further can be those with moderate-to-high Bell fertility (amounting only 470 acres) and study, Madden (1957), Findlay (1956), (1956). natural to island have led with moderate natural fertility (28,590 acres). Recent developments on the to those blocks The poorer agricultural soils can all be considered the marking out of a number of containing low fertility (124,040 acres), but representative plant communities which are to be as soils of natural peat preserved from burning and grazing. Formerly this includes 78,000 acres of soil whose agri- potential is in doubt. There are there was little interest taken by the islanders in cultural still some proposals For years Mr G. about 6,370 acres of poor hill soils that should be of this sort. many for 2,330 acres of Wisner was the only islander who was successful used afforestation, and about should be placed in in protecting an area of native forest from the steepland soils, which the The position is combined onslaught of livestock, opossums, and category of forest reserve. set out below: casual incendiarists. On the southern uplands less

470 500.5 HIGH NATURAL 1 ERTILITY . OF TO ...... MODERATE permanent pasture suitable for dairying (All of ploughable slope: adapted to short rotation or possibly occasional liming or fat-lamb raising. Small dressings of superphosphate advisable and production.) to achieve maximum pasture 28,500 Soles ov NATURAL EERTILITY ...... 110DERATE .. .. growth; (Regular fertilising with superphosphate necessary for maximum pasture sulphote of be found helpful soils.) ammonia, potash fertiliser, and lime probably \\ill also on these Acres Soils of ploughable slope l " **0 Adapted for short rotation pasture mainly .. .. 1.420 After additional drainage ...... 7.850 Adapted for permanent pasture mainly .. .. 880 After additional drainage ...... grass, permanent pasture 4.240 Adapted to marram .. .. ploughab/c Suits not of slope I 980 \dapted for permanent pasture .. .. , 130,410 Sams ov Low NATURAL FERTILITY ...... probably potash fertilisers (Hegular use of superphasphate, lime, sulphate of ammonia, mul also and in some cases copper and cobalt. \till be necessary on these soils.)

Soils q{plaughable slope pastures 32.410 Adapted to short rotation .. .. G 100 After additional drainage .. . .. 800 pasture Adapted to permanent .. .. 7, lan After additional drainage ...... pasture 78,050 Problem soils. probably adapted to permanent .. .. ploughable Suits not of slope 400 Adapted to permanent pasture .. .. 6, 370 Adapted to afforestation mainly .. ..

land additional drainage before they Thus it can be seen that by excluding the steep- soils require potential. poor hill can achieve their maximum land soils (2,330 acres), the soils unsuited position be in way: On development (6,370 and the The may summarised this to agricultural acres), 60,000 bogs Chatham Island, there are approximately peat soils of the raised whose agricultural drained of growing high- development is still somewhat of a problem (78,050 acres of well soil capable pastures known be suited agricultural producing when supplied with the appro- acres), the area to to priate fertilisers. At estimate development is approximately 75,870 acres. a conservative these 200,000 with ease, and a The full agricultural potential of this area will soils could carry sheep dairy In addition are a not be achieved without fertilisers, high-production fair number of cattle. there potentially valuable agri- grass and legume seed mixtures, good livestock, and further 15,000 acres of Hat- land for which the initial development good management. In addition, 14,610 acres of cultural

37 include drainage. In for in work must reserve, there are a of the agricultural advisory staff use the peat further 78,000 acres of land, which, although investigation of specific soil-farming problems. As problem present rated as soils at the time, will we are only at the beginning of a documented probably become history Chathams, a valuable agricultural asset at of agricultural soil use in the the in future. some time the agricultural information in the extended legend is This is the basic soil information upon which the but a tentative estimate, based on the limited ex- framework of an agricultural development plan for perience of the islanders and supplemented by the island should be built. The first step in develop- observation of similar soils farmed on the mainland. ment should consist in strengthening the extension It is provided more for the information of the agri- service of the Department of Agriculture so that the cultural advisory staff than as a guide for individual island farmers may benefit more from mainland farmers, who should not act on the suggestions farming experience of similar soils. If field trials therein concerning fertilisers without first referring predictions problems bear out the in this bulletin, the agri- their to the local agricultural instructor. cultural authorities on the island will be able to make a close estimate of the potential levels of meat, wool, or dairy production that could be achieved ACKNOWLEDGMENTS by the island farmers and, on this basis, plan for pro- additional facilities such as a meat-freezing plant, The author wishes to acknowledge the help better shipping communications, a central butter vided by so many of the Chatham islanders during people factory, and whatever else the preliminary trials the course of the soil survey. The of the and experiments indicate. Chathams have evolved a system of hospitality provided island The information in the appendix to this whereby the traveller on the recalls after- report deals more specifically with the properties of wards no memory of the driving sleet and sodden but lasting impression kindly, individual soil types. This information is sum- moor, only a of a marised in an extended legend accompanying the sincere, and sometimes valiant, island folk. Acknow- soil map in the folder. Both the appendix and the ledgment is also made to Dr R. L. Watters, New permission extended legend are in the nature of a tool for agri- Zealand Geological Survey, for to re- cultural research, which should be at the disposal produce two photographs.

38 APPENDIX

on DESCRIPTION OF SOIL TYPES AND THEIR ivorth-while response to superphosphate these have been found PLANT NUTRIENT STATUS soils. Similar soils on the mainland be molybdenum, but this to slightly responsive to Rendzinas Associated Podzolic Soils in and would need to be tried a carefully controlled be with experiment. Molybdenum should used Ohuku sandy clay (1*) Chatham farm lands be- extreme caution on the grey .Chis. soil. is a shallow black or very dark soil. poorly with. cause most of the soils- are so supplied developed . sandy limestone under broad- m soft major plant nutrients that unnecessary rnolyb- leaved forest. It occurs only in central part of badly the denum could throw the system out of profile covers 470 acres. The soil. in proportion the island and balance, -foo much molybdenum to be in road-metal quarry near Te become can well seen the some other plant food can more trouble- pockets, deepest Pohue. The soil. tends to he. in the farmer deficiency. some to the than a molybdenum

20 . of which seldom exceeds m. No closely comparable soils. have been mapped A deep profile under pasture shows: but typical so far on the New Zealand mainland, the features in with Ohuku soils have many common 3 in. dark brown (lUYR 3/4) sandy clay; very friable; of Te Waewae Bay district of weakly developed nutty structure breaking to the rendzinas the strongly developed coarse crumb structure; Southland. boundary merging, ri in. dark greyish brown sandy clay loam: very Very (2) friable; moderately developed medium nutty-to- Kahupiri shelly sand blocky structure breaking to strongly developed Kahupiri shelly sand occurs only in the vicinity coarse granular and single graid structure; Whanga Lagoon flattish or boundary distinct, of the Te on narrow, in. dark vellownsh brown sandy clay loom: very It . 0 gently undulating ridges and covers 460 acres. is developed medium blocky friable; strongly pipi banks formed on cockle and shell of varying structure breaking to strongly developed coarse boundary level in crumb and fine granular structure; age, each marking a former of the water the patches lagoon. There also a number of small of light brown are on white soft sandy limestone with on rnap, formed humus staining. similar soil, too small to show the on old shell middens scattered around the outer Sample is 0-4 in, sample col- island. These particularly numerous 69201- (table 4) a coast of the are To One. It is Owenga. lected under karaka forest near a very an the Kaingaroa Peninsula and at fertile soil and contains free lime. The soils are variable in depth, but all show a dark grey shelly sand with a shEup Areas of Ohuku soils were often sown down to very topsoil dark grey sand dogstail, change to white shells mixed with ryegrass, cocksfoot, crested white and have deeper in subsoil. Midden soils to the suckling clover, and sundry species of Poa in the the tend black. plants, whose colour is often an intense days of early settlement, and most of these topsoils persisted The Kabupiri soils are too small and scattered to particularly the clovers, have in the sward farming practice. good grass individual in and helped to build up a soil. Their receive treatment Their general behaviour is expected to resemble carrying capacity, according to Madden (1955), may of Ohuku sandy clay. They are stocked be in excess of four sheep to the acre. Nevertheless, that the year because free- Ohuku is limestone heavily for most of the the despite the fact that the soil a shell ridges in pre- profile be ranging sheep congregate on the soil the suggests that the soil may dressings lime ference to surrounding swamps. sufliciently leached to respond to of the pastures A similar soil, Miranda shelly sand, occurs on the when high-producing rye and clover are possibility Hauraki Plains of North Island, on the main- established on it. There is also the of a the land of New Zealand, and very closely comparable soil in Waikuku r ed unbter j type shown on the soils have been included the soils nt dt Canterbury Province. soil mapped along the coast of Refers to Bureau sample number.

39 Podzolic Soils from Aeolian Sand Zealand and they are usually not grazed. The closest equivalent soil is possibly Brighton sand on Kekerione sand, eroded complex (3) the coast south of Dunedin. The eroded complex of Kekerione sand is found in areas of unstable actively eroding clune sand and Te One loamy (4); peat (4a); young dunes that have been fixed by marram grass sand sand over shallow phases (4b, 4c, and 4d) (Ammophila arenaria); together with slightly older Te One moderately consolidated dunes, occasionally still soils occur mainly on the western sicle of plant showing remnants of their natural cover, the centre of the island, with smaller strips along which contained Poa triodioides, Pimelea arenaria, the northern and eastern coasts. They are absent pumila, Scirpus nodosus, Carex Calystegia solda- from the south coast. Formerly they carried mainly nella, Acaena novae-zelandiae (bidibidi), and shrubby vegetation with much Pimelea arewarm, Deveuxia billardieri. Most of the more palatable Scirpus sp., with a number of shrubs and small Olearia species in the original cover, such as Myosolidimn trees, which were mainly traversii and pros- hortensia ("Chatham Island lily"), Apium Myrsine chathamica. stratum, Sonchus grandifolius, have now been eaten Te One loamv sand (4) covers 5,340 acres. out by sheep and cattle. This complex covers A typical profile (fig. I6) under scattered Olcaria 4,240 acres. pasture trees and cocksfoot-dominated shows: Much of the area in the complex consists of rown or 4 e lain ma actively eroding soil with no recognisable profile differentiation. The profiles older and more stable on very pale brown (lovR s/m sand. in complex show: the peat Te One soils. also overly (4a). The sand is. 4 ft lower layers 10 in. pale yellowish brown (2-5YR 6/2) sand, seldom more than thick and the pale yellow 8/2 peat on or white (2-liYR and 8/4) sand- merge with the uppermost horizons. The relief is very gently undulating. Type 4a covers These soils are not sufficiently. stable carry im- to 1,140 acres. The original vegetation is not known proved pastures, and they should be planted with for certain, although massive Olearia grass traversit trees marram or with pine and macrocarpa trees, are common on this soil, suggesting that tlus species Marram-grass areas should be very carefully man- aged, for if they are overgrazed or accidentally

erosion. Fie. 16. To One loamv sand, near Te One

40 may once have been an important constituent in Four Te One soils were analysed (table 4); plant Soil profiles Te 6918 and 6922 from shallow sand over the cover. are similar to the samples One loamy sand in their upper horizons: schist and limestone respectively, and samples 6919 and 6921 from deeper dune sands. The top- 2)qfriable 1< am\ sal fertile high percentage base SOilS Of all are with ob my sand, saturations. greatly 9 in, bro vn grading to dark reddish brown (GYR 3 2) The Te One soils described above vary Over in their behaviour when farmed. limestone a red (7-avit 2, loamv peat. on -t) but they have a high initial fertility, with removal Te One soils also occur as a shallow sand layer of the forest there appears to be at first a sharp fall in over varying kinds of rock. The underlying rock, decrease and then a slow, steady the rate of growth. grasses usually in a ivindsivept coastal site and lacking pasture Clovers and cleep-rooted a mantle of iveatherecl material, is capable of im- (e.g., cocksfoot) do well and help to "pump up from limestone below. Where parting new properties to the soils derived from plant nutrients the lies patchily basalt lie far beneath the sheet of sand that over the rock or schist not too the sand, high initial fertility, surface. The Te One shallow loamy sand over the soil has a moderate to limestone (4b) is a notably more fertile soil than noticeably higher in the immediate vicinity of the Tc One loamy sand and is nearly as fertile as the rock outcrops. The deep Te One loamy sand and peat good Ohuku soils; the Te One shallow loamy sand over the Te One loamy sand over also have a pastures basalt (4c) is likewise enriched by weathering of initial fertility, but appear to deteriorate One 10amy invaded by bracken fern. the basalt outcrop, and Te shallow sand rapidly and are often over schist (4d) soils are occasionally slightly One feature likely to be common to all Te One better than the deeper Te One loamy sands. The soils is a marked response to superphosphate. partly farmers have found influence of the underlying rock operates Many that, with superphos- pastures through the physical and chemical weathering of phate, high-producing rye-clover can be outcropping rock and partly by extra plant nutri- established with comparative ease. The Te One ents absorbed by foraging roots and eventually soils are all freely drained and tend to clry out in in plant litter. Most deep-rooted grasses, returned to the soil surface of summer, although trees, and the shallow Te One soils originally carried coastal legumes are not always affected badly. Potash broadleaved forest or coastal scrub and they are topdressing is not yet widely practised, although usually better supplied with organic matter than it will probably prove profitable on improved deep Te One soils. grassland. Te One loamy except phases Type 4b covers only 60 acres; 4c about 1,190 sands, the shallow limestone and basalt, are all liable produce acres; and 4d only 80 acres. over to improved pastures of low copper content that may A typical profile from a site where there was affect stock health adversely. The cobalt content of 3 ft of loamy sand over limestone (type 4b), under is likely be low. the soil also to karaka forest, showed: Soils comparable to Te One soils. occur widely. on New Zealand A the mainland. very close compari- 6 in. reddish black (2-5YH 2/0-2/2) loamy sand; very friable: weakly developed coarse nutty son can be drawn with the Otatara loamy sands structure breaking to single grain and coarse mapped in. Southiand. crumb structure; boundary merging. 12 in. reddish grey (5YR 5/2) sand: friable to loose; boundary merging, on very pale brown (10YIt 7,4) loose sand (lime- Rapunui loamy sand (5) stone rock at 24 in.). Rapunui soils are formed from dune sands that A profile from a site where was comparable there . passage have become consolidated with the of time.. 2 ft of loamy sand over schist (type 4c), under They generally have features: an undulating or rolling topo- coastal forest, showed the following graphy. They cover an area of 5,980 acres. These but Te One soils are similar to, older than, the and 8 in. Very dark greyish bruton loamy sand; friable; profile moderately developed coarse nutty structure Kekerione soils, and their is consequently breaking readily to strongly developed fine developed (classed as semimature They blocky and coarse crumb structures; boundary more stage). distinct, formerly supported mixed broadleaved Draco- 6 in. brown loamy sand; friable, forest abundance ferns. on palc brown fine sand (schist rock at 22 in.). f)/tylllint with an of tree

41 profile A typical under forest shows: This plant produces an acid litter, which ensures 0-4 in. dry litter, that strong leaching of the soil continues. Burning in. dark grey ("iY R 3/1) loamy sand; friable; promotes 4) Very of the heath the spread of bracken, and developed moderately medium nutty structure gives this, when burned, way to a mixed community breaking to strong fine nutty structure; boundary distinct, consisting of stunted bracken with Libertia sp. and

rre erfriabl < unl’ plant 2 Leucopogon sp. This is the type of cover that n e vi Kairakau Wind 8 in, weakly cemented reddish brown sand ("coffee- nowadays covers most of the soils. rock"), erosion is active, and, consequent upon the periodic on pale yellow fine sand. plant burning of the cover, erosion in the form of Rapunui soils are likely have only small to "blow-outs" occurs sporadically throughout the reserves of plant nutrients in quartz-sand sub- the Kairakau soils. soil, and impact of 80 years of farming without the The Kairakau soils cover 340 acres. fertilisers has been severe. Only where there is A typical- profile is shown in fig. 6. A similar regular local concentration of stock or where the protile under stunted heath shows: forest cover is still largely intact has this soil kept fertility. part 2 in. grey loamy sand. up its For the most both the soil pale grey pasture 6 in. sand, fertility and the cover have steadily 8 in. very pale grey or pinkish white moderately deteriorated. It is a moderately well drained soil, cemented sand, brown br< although the "coffee-rock" horizon slows up move- 14 in, or reddish wn strongly comented humus-enriched sand ( coflee-rock ), gently ment of water on undulating topography, 3 in. very dark reddish brown weakly cemented and in shallow depressions temporary ponds may peaty sand, on white or pale yellowish brown sand. form in very wet weather. phos- places, yellow These soils respond very well to lime and In reddish staining of the white phate, or to phosphate alone. On improved pasture sand below the cemented humus horizon denotes livestock may suffer from copper and cobalt defici- local concentrations of iron, but rarely does a ce- far have pan ency although so only a few cases been menteel iron form in the Kairakau soils. definitely confirmed. The natural fertility of these soils is almost Comparable found Catlins soils are on the coast of certain to be low, and the present plant nutrient Southland and Otago, are mapped south where they status, lowered by a long history of burning, must Toetoes loamy as sand. be very low indeed.

Kairakau sand (6) The Kairakau soils would be expected to respond parent very well lime and superphosphate. Controlled The Kairakau sand has been formed on to experiments with potash and moly- materials similar to those of the Rapunui soils but topdressing bclenum be Available under forest dominated by mor-forming trees. No would worthwhile. copper and poor good examples of this forest now remain although cobalt are almost certainly in supply in these soils, and on improved pastures deficiency symp- it is almost certain that the dominant tree was in livestock be for. The pre- formerly Dracophyllum arborcum. In nearly every toms should watched 24 in. in case where Rapunui soils adjoin Kairakau soils, the sence of some of cemented sand the subsoil inevitably restricts grasses former show a pattern of numerous isolated patches the root range of and On small areas of flattish of pale grey sand, a yard or so in diameter, which trees. topography the soils become in if improved merge gradually into continuous pale grey sand. The may very wet winter, and, pastures is resemblance between these podzolised patches and are overgrazed, the sward readily grey podzolised patches broken, allowing rushes to invade very rapidly, the that on the mainland However, such adverse agricultural features are associated with kamahi trees (Weinmannia race- are en- in farming podzols, mosa) in the Catlins district of south Otago is countered on other sand and have not prevented mainland farmers from close, and one can relate their presence on the Chat- they building up productive lamb-fattening and dairying hams to the influence of individual, isolated Draco phyllum forerunners Dracopkvilum pastures on this kind of soil. trees - of the forest which gradually replaced the broadleaved The Kairakau soils in many places adjoin areas species and brought about a general acceleration of of deep upland peat, and where part of the edge of podzolisation peat has been destroyed by fire soil leaching and throughout the area. the a complex peat, The original Dracophylum forest was destroyed pattern of soils results; deep shallow, partially- long ago and is now, in some areas, replaced by a burned peat, leached sand exposed by the burned- heath community dominated by Cvathodes robusta. off peat, as well as normal Kairakau soils, are all

42 found in These I 2 per acre per annum of superphos- the complex. complex areas are with to cwt by peat phate initial interval of from shown on the soil map adding the soil and an two to three Only number (19) to that of Kairakau soils (6). This com- years under root crops or chou moellier. small 20 be annually plex is equivalent to soils mapped near Bluff in areas (5 to acres) should attempted grazing be Southland and named the Omaui soils. so that complete control can maintained young pasture. fern, gorse, over the Bracken and badly thistles almost certainly invade managed Podzolic Soils from Schist pastures. It may be anticipated that there will be low levels possibly, in Pukeraki fine sandy loam (7) of cobalt and, copper this soil. There are no close counterparts of this soil on This only in part . soil. occurs the northern of the The the New Zealand mamland.. most closely com- . best developed . island. on rolling country and is m parable soil. is at Mangatua in south Otago. Port Hutt Kaingaroa the vicinity of and on the Peninsula. It covers some 6,480 acres. The soil is derived from quartz-rich schist and is usually very Brown Granular Loams and Clays from leached plant Topsoils strongly of nutrients. are Andesitic Tuff pinkish pale grey or white fine sandy loam or, in places, loamy layer phase sand, often with an overlying Tiki brown clay (8); strongly rolling (Ba); 12 peat. The is of shallow (6 to in.) subsoil usually a Tiki brown hill soils (8H) pale brown, humus-stained cemented pan resting ,These soils. are well developed m the vicinity of directly on weathered schist. Waitangi township. Small areas also occur at Te A typical profile shows: Matarae, Kekerione, Owenga, Cape Young, and S in. reddish brown fibrous loamy peat, around the southern coast from Waitangi township to Owenga. Tiki brown clay is developed mainly w I m 1 d e sand, land, also areas on 4 in. dark brown strongly cemented fine sand. on rolling but there are small pale humus- 11 in. brown weathered schist, strongly strongly rolling land (Sa) and moderately steep stamed between rock fragments, basic land (SH). The soils are derived from tuff and on very pale brownish grey weathered schist. volcanic ash and were formerly covered with This soil formerly supported Dracophyllum forest. broadleaved forest which probably included a high Under pastoral farming (which normally includes proportion of Corvnocarfus laevigata (karaka) and periodic Island (fig. 17). burning to control invading bracken fern Olearia traversii (Chatham akeake) and heath plants such as Cvathodes robusta and On land of easy rolling to undulating topography Libertia ixioides) the original forest peat has almost where drainage is slightly impeded and the soils forest included fair completely disappeared, and nowadays the soil is are mottled (8b), the original a (nikau palm) proving to be a very poor medium for growth of proportion of Rhopalostylis sapida and natural pastures. With very careful stock manage- a higher proportion of tree ferns. rnent, about one sheep to the acre can be main- pasture tained on a rough mixture consisting of bracken fern (Pleridium spp.), Poa anceps var. chathamica, Holcus lanatus (Yorkshire fog), Agrostis tennis (browntop), Anthoxanthum odoratum (sweet vernal), Trtfoliant dubium (suckling clover), Deyen- xia crinata (plume grass), Gentiana sp., Blechnuin procerum, Luzula sp., Hydrocotyle sp., Gnaphalium

spp. Formerly crops of wheat and potatoes were grown successfully on this soil.

No sample was collected of this soil type but it is expected to be of low natural fertility, strongly acid, and poorly supplied with calcium and phosphorus. No improved pastures have yet been established soil although it is most probable on this type that Photo: R. L. waner pasture be following cye-clover could established growing li n. survivors of the coastal forest originally per the application of 2 tons acre of local shell lime on Tiki soils, near The Horns

43 Type 8 covers 3,360 acres; type Sa covers 2,090 township, shows that the soil is strongly acid and acres, and type 8H covers 1,470 acres. relatively low in phosphorus. The capacity to hold profile 4 typical of Tiki brown clay (8) (fig. I8) bases is high in both topsoil and subsoil. Potassium drained pasture in a well site under shows: is in fair supply. The sample was taken under pasture, ten-year-old browntop and the original 5 in. dark brown (7-fiYR 4/4 to 10YIt 4/3) clay; firm fertility built under karaka forest is now to friabic; strongly developed medium blocky up mark- structure breaking to strongly developed fine edly depleted. Responses would be expected from blocky structure; many roots; boundary difluse, both phosphate and hme.. 18 in. pale reddish brown (5YR (5/4) clay; firm; strongly developed coarse blocky structure breaking to moderately developed medium Tiki brown clay, mottled phase (Bb) blocky structure; roots common; boundary In poorly drained sites Tiki soils show darker 12 in. I sh brown clay; very firm; compact in grey degree place; strongly developed very coarse blocky topsoils and a moderate of mottling structure with slight columnar arrangement; in the subsoil. The mottles are coarse and common columns weather to strongly developed medium ’ are strong brown and pale grey in colour, and blocky and nutty structures; roots only between structural columns; boundary distinct, usually occur from 15 in. downwards. This soil pale yellow (2-5Y R 8/4) clay reddish on stained covers 950 acres. yellow and strong brown; firm, moderately to strongly plastic when wet; strongly developed 10 k structure ftragn enrti Tiki reddish brown clay (Bc); Tiki reddish brown hill evlumirclr atTegradually and merging into parent tuff beds soils (8cH)

Tiki reddish brown clay resembles the Tiki Chemical analysis of Tiki brown clay (6926 in 13rown clay in many structural features but is much table 4), sampled half a mile east of Waitangi brighter in colour and of stronger reddish hue. brown It is somewhat less friable than the clay. It is formed on rolling topography from material which is thought to be mainly subaerial volcanic predominantly ash of andesitic composition. It is confined to the downland in the vicinity of Wait- angi township. Formerly it supported coastal forest dominated by Olearia traversii, but most of this soil is now farmed. Tiki reddish brown clay covers 480 acres. A typical profile under pasture shows:

7 in. dark brown (7-liYR 3/2) clay; firm; moderately developed medium blocky structure requiring (when dry) great force to crush down to fine blocks and granules; roots common; boundary merging, :\in. reddish brown (iiYR 5/4) clay; firm to friable; moderately developed medium blocky structure breaking to strong fine blocky structure: roots common; boundary difluse, IN in. yellowish red (GYR 5/($) clay; friable to firm; moderately developed coarse blocky structure breaking to moderately developed medium and fme blocky structures; roots common, boundary merging, brown (7-liYR 5/(i) friable; on strong clay; weakly developed coarse blocky and nutty structure breaking to granular structure; roots few; weathering parent material appearing at 48 in.

On moderately steep to steep hills a closely re- lated soil is mapped as ScH and covers 120 acres. The Tiki soils are amongst the best potential grass-farming island. The fer- soils on the original tility accumulated under coastal forest was pro- bably fairly high, and where development included pasture the introduction of species such as cocks-

44 foot, ryegrass, crested dogstail, white and suckling near Waitangi township illustrates the high natural however, clover, and has been combined with efEcient stock fertility of the topsoil; it will be noted, in phos- management, the initial fertility of the soil appears that the subsoil is more acid and is low Some phorus. This helps will to have been well maintained. of the best to explain why the soil pasture-land in farming (see frontispiece) occurs the vicinity deteriorate under systems of that tolerate is poor pastures low It of the cliff edges, and it likely that uphlown silt and tacking rates. abo faces been phosphate and sand from the cliff have added as a suggests that regular topdressing with part grassland form of topdressing, thus helping to maintain soil will be an essential of rehabilitation. fertility. However, there are still many farms with It is also to be expected that most areas will show a poor pastures on this soil where the swards consist response to lime. The Tiki soils are distantly related hair grass, brown granular Waikato mainly of danthonia, sweet vernal, and to the clays of the loams), with only a little clover and trefoil. Unfortunately (Alorrinsville and Hamilton clay where farms potashisregularlyusedonhigh-producingpasture. farms of this type are more common than in South with good pasture, and it can be assumed that there There are no closely comparable soils the has been a steady overall decline from the original Island of New Zealand. level of fertility on this soil type and that there few lost plant have been attempts to replace the Mangahu clay loam (9); strongly rolling phase (Ha); nutrients by using fertiliser. The soils of deterio- phosphate Mangahu hill soils (911) rated farms show a marked deficiency in in foliage forage These are found mainly between Waitangi and nitrogen, expressed the of soils Owenga between Waitangi crops such as turnips and kale. township and and town- Sample 0927 (table 4) taken from an area of ship and (’ape L’Eveque, although small areas of north Port Hutt pasture on land recently cleared from karaka forest similar soils also occur to the of

45 hills prove associated with the conical that arise from the to have low natural fertility. The present con- peneplain. Mangahu leached dition pastures northern soils are soils of on this soil suggests that few formed from tuff sediments and local beds of basic farmers have been able to overcome this natural volcanic ash. They formerly supported a broad- disadvantage. Browntop, crested dogstail, sweet leaved forest in ferns rich tree and with numerous vernal, and some clovers and trefoils are the main peat-forming trees including Dracophyllum ar- sown grasses that have survived. Bracken fern and boream. Small, very local, patches of soil are found bidibidi have persistently invaded pastures. to be in a strongly leached condition. These are pale Burning has done little to improve the situation. grey ploughed in colour, so that the surface of fields Close fencing and heavy stocking with cattle have has typically a mottled appearance. Mangahu clay proved to be capable of controlling bracken fern, loam covers 4,370 acres. but a very marked improvement in the condition 4 profile Mangahu loam (fig. 19) pasture be typical of clay of the could expected from the use of pasture per under bracken fern and danthonia shows: lime (at least 2 or 3 tons acre) and of super- phosphate per (at least 2 cwt acre per annum). The 4 in. greyish brown firm to friable clay loam, most soils probably bc 2 in. Very pale brown friable to firm clay loam, nearly comparable are to fi in. dark brown firm clay with very coarse blocky found in the Waikato district in mainland New structure, often arranged conspicuous columns in Zealand, but is or prisms, the comparison not a very close one. yellowish brown friable firm on to clay.

The Mangahu soils also occur on strongly rolling Tuku silty clay loam (IU); Tuku hill soils (10H) slopes covering 850 acres, and a related hill sod (9H) Tuku silty clay loam is found commonly on the covers 6,330 acres on moderately steep to steep peat gully Waitangi fringe of the upland areas, particularly around slopes mainly to the south of town periphery profiles the of southern It is a very ship. Soil are similar to Mangahu clay loams the tableland. strongly leached soil from basic and covers but shallower, and on the steeper parts of the hill tuff Formerly plant Draco- is brought 5,260 acres. the cover was soils weathering tuff often to the surface phyllum forest with abundant ferns. by slip erosion. arboreum tree The former prevalence of supplejack (Rhipogonum No analyses have yet been made of these soil grimly scandens) is recalled by settlers who re- types. It is expected that the Mangahu soils will member the extra difficulty which this plant caused when bush was being felled on this particular soil. Tuku soils occur mainly on easy rolling and rolling slopes. Related hill soils (10H) covering about 40

acres are found on the moderately steep to steep gorges slopes of the of streams flowing to the south coast.

A typical profile of Tuku silty clay loam is shown in fig. 20. A similar profile under pasture shows:

4 in. pinkish grey (7.504 7/2) friable silty clay loani, 4 in. pinkish white (7-5Y14 8/2) weakly comented silt

silt loom grading into 2 in. Very dark reddish brown (GYR 3/4) silty clay

pale yellowish brown (10YR dark on (5/4) streaked brown and reddish yellow clay; compact in place, vestigial iron-pan layers occur around lumps of weathering tuff.

Sample 6808 (table 4) is from a very strongly podzolised area of Tuku silty clay loam beneath the acid litter of a single Dracophyllum tree. It is more acid and much more leached of bases than the Tiki soils. This soil will obviously have severe limitations when farmed without fertilisers and lime. Reduc- 1 ig. 20 Roadside exposure of Tuku silty clay loan phos- tions of the acidity with lime and raising the developed basic beds. Three in tuti miles south waitangi phate level would be the first logical steps to take of township on road to Tuku

46 in build high- Rangitibi hill suffered some damage by order to a soil capable of maintaining soils producing pasture. erosion when their original forest cover was first Tuku have felled, but in have This analysis shows that the soils a most cases they subsequently plant in developed good grass in very low reserve of nutrients the subsoil, a sward rich clover and forest have been and once their small supply of accumulated able to maintain this through many pastoral fertility is exhausted, there is little enough to decades of farming. Only a very few cases nourish pasture plants. It is therefore not sur- of overgrazed, deteriorating pastures were seen on prising herb grass Many benefit from phos- that the initial and cover, which this soil. of these would burning phate possibly also from small came in following the of Dracophylum topdressing and per potash, but, for forest, has but a short life and soon degenerates to dressings (up to I cwt acre) of part, have fern and heathland. Only browntop, sweet vernal, the most Rangitihi hill soils seem to persist, plants and bidibidi seem able to and these adequate mechanism for maintaining their natural are successful mainly along the trails frequented by fertility. Somewhat similar soils occur in western travelling stock. Trefoil is commonly the only Southland, but the most closely comparable soils poach if Dunedin. legume present. Tuku soils tend to badly are the Wakari hill soils near heavily stocked in winter, and in dry spells poached surface layers usually set into a hard pavement. Tuku soils are expected respond quickly to to Hokopoi hill soils (1 2) small but regular dressings of hme. and superphos- The Hokopoi hill soils are leached soils formed phate. At Wharekauri Station, where a small area from basaltic rocks and are usually restricted to of this soil occurs, excellent crops of roots and chou moderately steep steep, or very moellier have been grown by using lime and ferti- small areas of to slopes. They are not large enough liser, and rye-clover pasture establishment has strongly rolling proved Consistently good in area (420 acres) be of marked agricultural to be relatively easy. to significance in Chatham Islands. Formerly stock management is essential. The use of molyb- the they a mixed broadleaved and Dracophyllum denum is not advised until carefully controlled carried forest, similar on the Mangahu experiments have been carried out. Copper defi- arboreum to that soils. ciency is liable to occur in lambs where Tuku soils profile pasture fattening A typical on a 200 slope, under are the main soil of the and weaning fern paddocks. and shows: There New are no closely comparable soils of the 4 in. dusky red (2-5YR 3/2) clay loam; very friable; Zealand mainland. Distantly related soils are to be moderately developed medium nutty structure breaking to very strongly developed very fine found in Northland and Waikato. the granular structure; many roots; boundary distinct, 8 in. reddish brown (nVR 4/3) clay with occasiomil Brown Granular Clays from Basaltic RockS Weathering stones; very Brm: weakly developed coarse blocky structure breaking to strongly developed fine blocky and granular structure: Rangitibi hill soils (11) weathers to an irregular columnar structure: These are some of the best farming soils of the roots few; boundary distinct, a 41)ve Chathams, but unfortunately are restricted in area on darji Idisldro in i a IT (390 acres) and are confined to moderately steep and The Chemical analyses (table 4) show that the steep slopes in the vicinity of basalt outcrops. 1-lokopoi hill soil, sampled in the headwaters of original vegetation was broadicaved forest, in- Hawaiki River, is the strongly acid and strongly cluding many species common also to the broad leached of bases. There are no closely comparable leaved forest on limestone soils. soils mapped on the New Zealand mainland. A typical hillside protile (200 slope) under forest When the forest is cleared from these soils a fair shows: initial pasture can be established, and clovers

3 in. ver "’ Within few years, however, flourish for a time. a 3ter e n et i)u la ri to 1<1 cle 01 pasture per- developed fine deteriorates and the main species structure breaking to strongly the blocky structure; boundary diffuse. small stones sisting are danthonia and sweet vernal: clover on surface. common the almost mvariably. disappears and bracken fern, 4 in, brown (10YR 5/2) bouldery clay; friable: very bidibidi invade After less 10 strongly developed fine blocky structure breaking and strongly. than rangly developed line granules; boundary years of pastoral farming it is usual to find strong- ers growing bracken fern completely taking over. weathering basalt. on

47 Since is low fertility, it is flushed plant from this soil clearly of natural with extra nutrients derived the likely that improved pastures will require regular weathering basalt. In such situations they can be topdressing anel liming. Probably at least two tons regarded as moderately to highly fertile soils. periodic of lime to the acre will be needed and These soils need considerable drainage before they heavy dressings of superphosphate (4 to 5 civt/acre can be used for intensive farming, and once drain- four years). On high-proclucing has been improved be every three to age they would expected to pastures potash give may a response and experi- respond to fertiliser in a manner somewhat similar ments may show that molybdenum does likewise. to the Tiki brown clays. Molybdenum, however, should not be used except

under expert advice and control. Huro grey clay (13a)

This soil is likely to be more extensive than actu- Hokopoi-Tuku complex (12a) ally indicated on the soil map for it tends to occur This soil complex is found on broken rolling iviolely in very small patches, sometimes less than country south of Waitangi township, where basalt 5 to 10 acres in extent. This soil covers a total area crops out amongst leached soils derived from basic of 420 acres. It is usually found in association with The forest broadleaved Mangahu, Tuku, Hokopoi is tuff. original cover was and soils and some- fairly proportion forest with a high of tree ferns what more leached than the typical Huro mottled and Dracophy//um trees in the canopy. clay. Broadly speaking, the clay loam component in A profile under forest shows: the complex is a soil related to the Hokopoi hill 5 in. dark grey salty. clay, very slightly plastic, soil, loam is and the associated silty clay usually 8 in, strongly mottled grey, brolin, and reddish the Tuku soil. No additional soil samples were yellow plastic clay, on pa compact clay with course brolin collected. Both main in complex are the types the tiegrey considered to be strongly leached soils of low nat- The Huro grey have ural fertility although there is likely to be some clays are considered to a improvement in nutrient supply in the vicinity of moderate to low natural fertility and would be liming outcrops of basalt rock. Pasture improvement and expected to respond well to and superphos- phate fertiliser response would be expected to follow the once their drainage has been improved. pattern mentioned under the Hokopoi hill soils and the Tuku silty clay loam. No comparable soil grey peaty yet Huro clay and clay loam (13b) complex has been mapped on the New Zealand mainland. This soil occurs mainly in association with Tiki and Mangahu soils on land of gently undulating, pasture rumpled relief. Originally brought into from Gley Soils forest, these soils are now generally invaded with rushes and fern. Usually the peaty component of Huro mottled clay (13) grey the complex occupies the depressions and clay This in patches soil occurs small scattered widely occupies the low hummocks. The peaty clay loam island, usually in association with pale throughout the may be up to 4 ft in depth, overlying mottled Tiki, Mangahu, and Hokopoi soils. They are grey brownclay.Atypicalprofileofthepeatycomponent

greyish loams M or brown clays and clay with moder- shows: ately to strongly mottled subsoils. Their original gr th nb vegetation is not known for certain but was prob- "’ ".:-1: >eat j ){ red forest palms lilonj1 ably broadleaved with abundant nikau plastic clay, This brown mottled compact clay. and tree ferns. soil covers 820 acres. on A profile under pasture shows: typical 1-luro grey clay and peaty clay loam is diacult form 6 in. greyish brown firm to friable clay, to farm because the component soils such an l intricate pattern. Thorough drainage is difficult 101 i r tl sttles, is hummocky; yet o\r{ where the micro-relief without drainage, Most Huro mottled clays appear to be moderately a large measure of successful the operation fertile. Where they occur in association with fresh- of farm machinery is far from easy. water springs (these are often found emerging below The most nearly comparable soils on the mainland Southland. basalt outcrops on sloping land) they are usually are the Makarewa soils of

48 Organic Soils Originally this soil supported forest, and in many places the Hapupu soils are very stumpy on the Pateriki peaty sandy loam and loamy peat (11) surface. In some places the stumps lie just below peats places Pateriki soils are moderately cleep rush with the surface (18 to 24 in.), and in a few tree a slight but variable amount of blown sand through- stumps have never been reported. No soil samples profile. out the Many areas are still rush swamps, were collected, but the natural fertility is estimated for grazing plant and where used rough the cover to be low. Local experience suggests that the estab- is now tending to differentiate into bracken on the lishment of improved pastures requires a good deal parts per further dress- higher and moss-rush communities on the of lime (2 tons acre initially and lower parts. The four years for trampling action of cattle seeking ings of I to 2 tons every three or feed in lower-lying parts has been Shallow ploughing is possible summer the several years). only partly responsible for this differentiation. Pateriki on the stump-free areas. The best examples of soils cover 3,010 acres. improved pastures seen on this soil type had been over a period of four years A typical profile shows: established three to during which avinter-feed crops are grown and fed ly n(\itli c>ff in small blocks so that there is very heavy a li ysan for period year. This helps occasionalr<{-edelbsjacbands of pale brown fine sandy loany. stocking a short each per to consolidate the topsoil. Lime (2 tons acre) The natural fertility of these peats is low, and and superphosphate (1 civt per acre) were used their unimproved stock carrying capacity is less with each crop, and superphosphate was used 3 Stock fourth fifth year, than one sheep to acres. appear to alone, in the or when the remain healthy while grazing on the present rough rye-clover pasture was first sown down. Copper pasture land, but this soil is expected to become deficiency should be watched for on these soils. copper-deficient when used for intensive farming. Similar soils occur in a similar zone between Where there are layers of volcanic ash close below dunes and peat in Southland and Stewart Island. the surface of the peat, copper deficiency may not appear. Matarae peaty loam (16) Experimental work is necessary to find the best This soil is found in the valley bottoms of the way to raise the level of production on these soils. larger streams and where smaller streams debouch Draining followed by oversolving with a temporary on flat land. Matarae sods still carry a fair pasture mixture (mainly Yorkshire fog and lotus) to amount of broadleaved forest, usually with a dense has not proved satisfactory so far. There is probably ferns, and often vegetation for lime undergrowth of tree the need and topdressing, and the stock shouki is well laced with supplejack vines. The soils are be controlled fairly closely during the period of cleep peaty loams with a varying amount of alluvial pasture establishment. place silt and fine sand. These soils take the of Similar soils have been mapped in Southland. alluvial soils on the Chathams. They cover 5,160 acres. peat Hapupu sandy (15) A typical profile under forest shows: This soil is occasionally found where sand dunes 10 in. very dark grey peaty loam, peat loam, less peaty, and lowland meet. It is formed by the blowing IS in. Clark brown (wet) more or pale brownish grey silty clay or fine sandy loan1. of dune sand into peat, and there is a slight textural <>n is by range, which controlled mainly the rate of Drainage of the Matarae soils is usually not accumulation of sand. Where dune erosion is the difficult where the main stream has cut down into severe, sand accumulation is very rapid and the the valley floor or where the slope of the land has approaches a peaty sand. Where texture the a moderlate fall. Grasses and clovers come in accumulation of sand is slow, textures are more Matarae readily on drained soil, and as a result the peat 10am. The nearly sandy commonest texture soils are usually heavily grazed by free-ranging is peat. Hapupu grazed, encountered that of sandy soils sheep and cattle. When thus heavily rushes an of 1,420 acres. cover area and ferns soon invade. Potentially, these are useful good A common profile shows: soils, and appear to be of natural fertility. Similar soils occur in south Otago and Southland, peaty where they have been mapped as Waitepeka I I , loam. on dark reddish brown peat.

49

4 Mautere loamy peat (17) it in. dark reddish brown librous peat; weakly humilled and very weakly decomposed, This soil occupies lowland depressions in the 0 in. dark reddish brown fibrous loamy peat, moder- vicinity of many lagoons in the central and northern ately to strongly humified, weakly decomposed, IS . red-brown loamv pcat; moderately decomposed part of The parent material,. generally a In. the island. on red-brown peaty loom: strongly decomposed. rush or fern peat, is usually not more than 4 ft deep Agricultural improvement has been and tends to be slightly fibrous throughout. A scarcely on Tapuika peats. A few pasture related soil, also mapped as Mautere loamy peat, attempted the plants and weeds have established themselves along occupies many of the wide valleys in the upper reaches of streams draining the southern uplands. regular stock trails and there seems no reason why places, portion improved pastures anel even some root crops could in some the central of the Mautere not one day be grown upon comparatively soils tends to build up to form a typical "raised these peat elevated peaty areas. The problem of efficient drain- bog" on which Tapuika soils may develop. will have be solved. Lime will be needed and Mautere soils cover 4,920 acres. age to phosphate. Similar in A typical Mautere loamy peat profile shows: also topdressing with soils district potash. the Waikato are topdressed with 12 .an. Very dark reddish brown librous loamy peat Copper deficiency- could also be expected on the weakly to moderately humified. is in. dark reddish brown slightly fibrous pent Tapuika soils.

in cratt cl o In Southland, somewhat similar peat soils have decomposed. all r icl

The NIautere soils are used only for rough peat grazing. Many areas have consolidated tirmly and Awainunga (19) evenly and are suitable for experiments in pasture This is the most widespread soil on the Chathams Pastures, however, poor, establishment. are usually (to,060 acres), and is developed on a substratum of and Yorkshire fog is only grass really peat greater the thriving. (3 to 30 ft deep), which blankets the in some places closer drainage would be needed part Chatham of the landscape. There are no programme pasture before a of improvement could obvious differences in the peat blanket associated be started. Both lime and superphosphate may with variations in the underlying rocks except that prove to be essential for good pasture establishment, peat the overlying the consolidated sands of the but is considerable experimental work needed. The central and northern Pleistocene peneplain is usually fertility Mautere natural of the soils seems to vary. of very gentle (almost flat) relief and consequently In places developed in many they are association a surface layer of rush peat and moss peat is with small spring-fed swamps, and patches these appearing wherever stock have been allowed to usually have much higher fertility than the rest of roam. Apart from this, the peat undermass of the Mautere soils rnay prove be slightly the type. to Alvainunga organic soils is not true moss peat so copper-cleficient. much as a mixture of forest, fern, and rush peat. Comparable in Otago, soils occur south where From a field examination of eight deep peat pro- have been mapped as Stirling peat. peat they files (exposed as a result of fires), ranging from 8 to 20 ft in depth, no clear sequence from rush to forest peat or regular cycles of peat development Tapuika peat (18) could be detected. Raised bogs fairly features peat are conspicuous of the The beds show a natural banding, with dark Chatham Island lowlands. They range in area from peat layers alternating with lighter-coloured layers few yards pale a square to well over a square mile in a of fine ash of volcanic origin, and brown layers few The Tapuika formed peat cases. soils are on them of that are highly "mineralised" by the addi- in general, prominent and, are much more fibrous and the tion of blown sand. Using the more ash organic material is much less decomposed than in bands as reference horizons, no general sequence of Mautere loamy peats. Originally profiles. the many of the formation could be worked out for the eight Tapuika soils were forested, but today almost all The sequence is confused by the presence of layers are covered with fern, which varies in height of ash produced by subterranean peat fires. Pollen depending upon the history of burning in the area. studies might clear up the problem, but much of the The least-burned areas show a vigorous regrowth of variation seen in the deep profiles could result from Cvathodes robusta coming through the bracken. purely local phenomena. Take, for example, the Tapuika peat covers an area of 2,490 acres. most recent sequences of peat formation. The sur- A typical profile shows: face layer is often the product of accumulated

50 plants; Three profiles given residues from heath below these are layers of of the more common are forest peat, and from the buried roots it appears that below:

tree mainly responsible ivas Dracophyllum arbor- the Peat under Oracuphyllant arboream forest: a species appears have a wide eunt that to toler- yellow raw humus composed of 12 in. reddish dry, . leaves; ance of wet or sheltered or wmdv situations. Dracophylan, litter and tree-fern very quantity produced is weakly humitied; very few insects, no worms: The of litter by this tree truly d individual build up ja71trous copious, and trees normally a in. 1), peat (fibre mainly from < mounds of dead leafy residues not unlike the lamina of Dracophyllant leaves and vascular leaves); moderately pukau" kauri in North Auckland material from tree-fern mounds of the few insects and small worms; boundary (Robinson 1949). Where Dracophylum-dominated gunrified; forest still persists it is commonplace to find 30 to 8 in. reddish brown peat; moderately to strongly 11umilled; no recognisable plant remains; many 40 in. raw DracOfhyllant litter under inclividual Of small worms; boundary diffuse, peat trees. Dracophy/Inm is so widespread that one on brownish red peat; strongly decomposed; no plant dead can only conclude that forest of this type almost recognisable remains other than Dracophyllant roots; no worms. certainly covered much of the Aivainunga soil area I’cat Cyathodes heath: pre-Moriori soil under robusta in times. Both the dry litter and the 0 in, is itself highly burn so Tilgm tree are resinous and easily, I ea no n 3 5 potent factor bracken fronds;at%d moderately strongly that fire becomes a very and can of to humitica; many roots; a for insects; no worms; readily bring about widespread modification of the boundary sharp, plant The fires past fely centuries have peat; friable; cover. of the 6 in. Very dusky red loamy very fine parts landscape nutty structure breaking to crumbs; small worms resulted in the convex of the gy noperseentts) en;ss parts becoming becoming drier and the concave }>reses mT@ 1 pro- wetter. Peat formation on the former sites is libres; strongly humified; grading to moderately decomposed; boundary merging, ceecling under heath communities dominated by set s in. react tribrow at,lo Cyathodes robusta and bracken fern, while in depres- < 1 peat peats diffuse, ilJa,dec ; support Dracophylbunt into which there humilled; no insectsten7ror worms; boundary sharp, 5 in. pale brown fibrous peat; many living and dead is a gradual infiltration of the original dominant - rush roots; no insects; a few small worms; weakly In Dracophyllum arborent. the continued absence 11umilled; boundary merging, grazing, in, brown slightly tibrous (loamy) peat; no living of fire and one would expect the ultimate -0 organisms to be seen with naked eye; moderately of Dracophy//unt-dominated forest and a return decomposed; hne living and dead roots fairly period forest-peat build- return to a of widespread common; boundary difluse, presence peat profiles lavers red-brown pcat; moderately to strongly decom- ing. The in the deep of no pos la blown some of enriched with sand suggests that the asonse rr cl e 1 v s:Te7 lires passed through and destroyed part of the seen. coastal and dune forest, thereby setting in motion Chemically Alvainunga peats are extremely local dune erosion. This process can be seen in oper- the peat burn poor. Three of surface and litter have ation after fires, started by farmers in order to types been (samples 6924, 6917, and 6925 in out rushes, have escaped from the swamps into the analysed dune They are all very strongly acid, low in marram grass areas and laid bare the sand, table 5). low in incor- and phosphorus, and are often which soon starts to blow inland and become calcium be porated peat Subterranean potassium. Copper deficiencies would expected with the adjacent soils. phenomena if improved pastures are established on this soil. peat fires are local and seldom extend Experiments in the pastoral development of these for more than a few acres. soils should include trials with addition of these From it be the above account, will clear that the four elements. peat" nutrient soil type shown on the map as "Alvainunga The Alvainunga soils have been used for rough includes a wide range of slightly different kinds of years grazing for of 60 and there has been peat as well as peat soils. upward limited Microsohinet a spread of diversifedfinn uplands. They occur usually on easy rolling to (water fern), Acaena novae-zelandiae (bidibidi), and rolling country. The Rekohu-Awainunga complex Holcus /anatus (Yorkshire fog), and other intro- consists of a mixture of shallow Awainunga peat duced grasses, mainly spread by grazing livestock. soil and various kinds of mineral soil exposed by in places young plants gradual peat some of DracopkWhtm the oxidation and burning-off of the paludosum grazed have been heavily and taken on blanket. form, but for part a cushion-like the most other places in some the upper 2 to 3 ft of the soil is indigenous woody species show little evidence of still formed from peat (fig. 21). The nature of this having been grazed. peat varies. The lower layers of peat may show a As a subject for land development, the Awai- succession of forest, rush, and fern peat, while the nunga soils must still rank as problem soils. It is uppermost peat layers are almost always forest possible that they will respond to the treatment peats. peat In some cases the whole depth of has suggested below for the Rekobu soils, but con- clearly been built up under forest. The mineral siderable pilot experimental work should be done soils below the peat are somewhat varied in nature: before any attempt is made to develop the Awai- often they are strongly leached and gleyed sands nunga soil for intensive farming. The Awainunga (Kairakau soils), fine sandy loams (Pukeraki soils), peats are not directly comparable with the majority or silt loams (related to the Tuku soils), wholly or peats of now being farmed on the mainland. the partly cemented. Where fires have destroyed the Their closest counterparts are woody peats the Awainunga peat blanket or where farming opera- peat) plateau (Kaherekoau on the upland of south peat few tions have reduced the depth of the to a Otago and Southland, and some of peats the of inches, mineral material becomes soil forming. pastures the Stewart island; on these, improved have This results in the creation of a mosaic of mineral so far made but little headway. and organic soil, which is dif6cult to map on reconnaissance survey. The Rekobu-Awainunga

Rekohu-Awainunga complex (21)) complex covers about 9,550 acres.

These in patches Soil profiles vary very widely. Only one example soils occur throughout the be given: island, but all the chief areas lie on the south will

peaty loom; friable; 12 in. Very dusky red (10YR 2/2) many bracken rhizomes and roots giving a coarse librous structure, although the soil itself is nutinly well humitied, in. grey (SY R 5/2) very fine sandy loam; -1 reddish weakly cemented: compact in place; massive: aggregates are in very large blocks with strong humus staining along vertical cracks; boundary mergmg, 3 in. pale brownish grey (10YR 6/2) fine sandy loam: moderately cemented; massive; fewer vertical last tissures and less humus staining than horizon; boundary merging, 0 in. dark brown (7-5Y R 4/2) fine loanny sand very strongly cemented (coffee-rock); boundary sharp, 12 in. pale brown (7-5YR 6/4) with varicoloured, irregular large mottles (mainly pale brown, 10YR 6/3 and light grey, 10YR 7/1) sandy clay; weakly deveh>ped coarse blocky structure, blocky breakmy to strongly developed medium structure; sticky and plastic; boundary difluse, on mottled sandy clay gradually merging into strongly weathered tuffaccous sandstone.

peat layer Samples from the surface (6809, 6923, table 5) show that the soils are acid and relatively low in lime, potash, and phosphate. The mineral horizons below (6809, table 4) are very acid and very low in phosphate and bases.

This soil complex formerly supported a forest Fig. 21. 11 I lil’artAlvamean@k mainly dominated by DracopkWhent arboreunt. r z i clof I Tree ferns, particularly Dicksonia squarrosa, were Alvainunga soil complex, near Te Whata trig.

52 Saline Soils abundant. The commonest broadleaved trees were Olearia and Senecio luentii. For upwards of traversii Te Whanga peaty loam (21) years forest, 20 following the destruction of the the grazing but, This soil is developed along the eastern margin of soil provided rich for stock, as the grazed brackish Te Whanga Lagoon. It is very variable forest grasses and herbs were out and as the gently peaty dried heath plants and includes a number of small undulating the topsoil slowly out, lakeshore dunes scattered (notably Cvathodes robusta) and bracken fern be- shell-banks and sand years, wide, flat, brackish swamp, densely came dominant in the vegetation. For many throughout a Te Whanga bracken became covered with tall rushes and sedges. annual burning of the an estab- gave an area of 2,720 acres. lished farming chore. This some measure soils cover in A profile shows: of control over the bracken, but it also resulted good deal peaty the destruction of a of topsoil. in. dark brown peaty sandy loom, the 10 Very rethlish Obrous. In the absence of fertiliser, the mineral soils are 10 in, brown sandy peaty loam: slightly peaty factor even harder form the soils a grazing for to than - This type is used seasonally as rough import- awaken some farmers to dependmg that tended to the sheep and cattle. The water table varies peat. years, burning ance of surface In recent lagoon. In 1956, the upon the state of the outlet of the has been much less common. There is now constant lagoon had when the area was soil surveyed, the between farmers on one hand, who warfare the the been closed by a sand bar for 18 months. It was logs, are employing crushing with heavy chopping fall by claimed that the lagoon level would about with discs, and heavy stocking with cattle, and the Black 9 ft when the outlet was reopened. swan fern other hand, which finds conditions on the normally nest amongst the thick rushes and swan peat blanket increasingly its likmg. as the item in diet many to eggs are an important the of disappears. Chatham island farmers. Pukekos and wekas are in rushes. Successful development of this soil will require also very numerous the piecemeal. Efforts Considerable of Te Whanga soil might be that the problem be tackled areas quite provided lagoon outlet should be concentrated on a small area, well reclaimed easily the for water levels could be controlled fenced, which can be disced two or three times was modified so that be developed fairly levelled harrows and at will. The soil could the first season, then with then good pasture land. The natural fer- consolidated by stock, and subsequently sown down readily into drainage present pasture, be dis- ility of soil is high, and would to temporary which can mown to the difficulty if general level of water in the courage the last of the bracken. It should also be no the the heavily stocked from time to time to consolidate lagoon was under control. been in South ground. Often it be found peat Similar soils have mapped the the will that the Island New Zealand under name Motukarara. does not consolidate evenly (owing to its variable of the composition), and it will be necessary to see that particular, do by cattle, in not create small swamps grazing persistently in damp hollows where too the Soils Steep Hillsides lush. Skeletal of the spring and summer feed tends to be more Shell lime at I to 2 tons to the acre, superphosphate Awatapu steepland soils (22) possibly potash per at 2 cwt per acre, and at I cwt The Awatapu steepland soils are found only on be raise level of fertility acre will necessary to the precipitous mainly along the very steep to cliffs, point be sown of soils to the where they can these south coast of Chatham Island. They cover improved pasture. the down to root crops and rye-clover broadleaved some 2,330 acres and support mainly deficiency be soils. Copper may expected on these by forest and shrubs, usually closely shaped the is The point for the farmer to remember that the wind. peat provides profile mineral soil below the no reserve of A typical shows: provides plant food, and, moreover, no reserve of brown clay loam with bouhiers. peat 3 in. dark stony summer. The skin. of surface loam boulders. mOisture in the 7 in, brown very stony clay with farm. basaltic rock. is all important to the and every effort on weathering for long should be made make it last as as fertile but owing to They appear to be very soils to possible. precipitous are completely their slopes they liekohu have yet No soils comparable to the soils unusable. parts Otago Peninsula. New Zealand mainland. Similar soils occur in of the been mapped on the SOIL CHEMISTRY phosphorus plants of the available to but if the By R. 13. MILLER and L. C. 13LAKE.110RE amount of organic matter is not high the figure gives phosphorus a useful indication of the status. 1 Tables of Soil Analyses Most of the samples from the Chatham islands are high in organic matter, but those that are not are Data for the chemical analyses of samples generally phosphorus low in (3 to 6 mg P%) or collected in course of soil survey are set the the very low (less than 3). in Table 4 out tables 4 and 5. contains the analyses of mineral soils, and table 5 contains the analyses Organic Matter of leaf litters and organic soils. The analyses were out by Mr M. FitzPatrick, Miss M. Young, percentage carried The of carbon indicates the level of Miss N. V. Bailey- and organic matter in the soil. A figure less than 4 is considered low, and if it is above 10 the soil is Notes on Analytical Methods Used considered peaty. The ratio of carbon to nitrogen indicates whether the organic matter is somewhat The sod. and litter analyses given in tables 4 and (little decomposed greater IB), or raw = than 5 were done by the methods of Metson (1906). In mellow (well decomposed 10 to 12). When the soil,. phosphorus was determined by extraction with. = is is sample almost entirely orgame it. treated as a 1% citric. acid, pH with. a glass electrode on a litter, and total analyses are made (see table 5). 1:2-5 soil/water suspension, and cation exchange These analyses give a measure of the ability of the clata by leaching with neutral, normal ammonium vegetation to return nutrients to the surface soil. acetate followed by washing with 80% alcohol.

Litter analyses were done by igniting the sample at 5500c to constant weight and then dissolving the Exchangeable Bases ash in dilute hydrochloric acid for determination -The various determinations under the headow. of phosphorus and bases. Cation Exchange" important .. . are as not only In . for they soils containing free lime. the figures potash show the lime, magnesium, and levels m. the exchangeable calcium. and total exchangeable bases soil but show how much of these the soil can hold were not measured as it may be assumed that, in ’ and also indicate how much . needed to bring. dominates is the these, calctum. the exchange complex. soil. up to a given level of fertility. The cation exchange capacity indicates the ability Notes on the Interpretation of Analytical plant of the soil to hold these nutrients. Capacities Data range from less than 6 (very low) to more than to (very high). Organic matter has a high exchange To help with the interpretation of the chemical peaty have analyses the following notes will be useful. It capacity so that soils often capacities 60 100 The should be remembered, however, that many other of to m.e.%. amount of nutrients actu- present (total bases) is less factors must be taken into account before the ally exchangeable usually in leached it be figures can be translated into agricultural practice. than the capacity, and soils may only a few per cent of the capacity. This percentage percentage is base A percentage H called the saturation. base saturation between 20 and 40 is considered This figure gives a measure of the acidity of the low and between 60 and 80 high. If free lime is A has pH 7; sample. neutral soil a value of with present, from, for example, limestone parent mat- increasing acidity value falls so extremely Ohuku the that erials, as in the soil sample (table 4) or from acid soils have pHs below 4-5, strongly acid soils in Te One phase shell as the sand, shallow over from 4-6 5-2, moderately acid 5-3 5-9 range to to limestone, the soil is generally 100% saturated and slightly 6-0 6-5. Alkaline soils have and acid to the percentage base saturation measurements are greater values than 7, and these usually contain not made. free lime. The great majority of Chatham island -The exchangeable cations are calcium. (Ca), soils. are acid.. magnesium (Mg), potassium (K), and sochum. (Na). Normally calcium is the major element, followed by Phosphorus magnesium, potassium, and sodium. In Chatham Phosphorus in soils is measured in an extract Island soils, relatively high magnesium and sodium made with citric acid. This is not a direct measure figures are attributed to cyclic salt from the sea.

54 - St

ICL

I

- Ti

55 problem Shortage of magnesium is not likely to be a laevigatus). This litter (sample 6921A) is alkaline for farmers, but figures for calcium and potassium (pH 7-5) and contains a high amount of phosphorus potassium are low in some of the subsoils, so that lime and (305 mg% ), calcium (193 m.e.%), and potash probably could be added to these soils with (6-05 m.e.%). advantage. The mixed litter of coastal forest (Cortatocurfus, Macropiper, and Olearia mainly) (sample 6918A) is only very slightly acid (pH 6-4) and shows Discussion of Soil. Analytical Data reasonably high levels for phosphorus (184 mg%) A brief interpretation of each analysis shown in and calcium (100 m.e.%) and a moderate level table 4 is included in the description of separate for potassium (3.60 m.e.%). The coastal forest A few general given below: soil types. comments are litters are also richer in magnesium (32 and 39 sodium (9 10 (1) The high cation exchange capacities and phos m.e.%) and and m.e.%) than other litter for island. This phate figures indicate that the influence of types of analysed the would be because organic matter is greater than in most New expected salt-laden winds strike with full impact on forest Zealand soils. This is associated with the this community. in litters from forest, general tendency towards peat formation under contrast to the coastal the litter from Dracophy//um forest is Under most types of plant cover. very acid. proportion few Dracophyllum (2) There is an unusually high of mag- one of remnants of very old forest litter (sample 6924) has pH nesium and sodium in the soils. These cations arboremn the a of 4-9 shows low of phosphorus are undoubtedly carried inland from the sea in and a return (68 (48-8 m.e.%) and spray and rain. Much of the sodium appears to mg%) and calcium a moderate potassium (3-35 m.e.%). Under a much wash through the soil, but the magnesium is return of younger forest Dracophyllum paluctosum, strongly retained and in some soils the figure of an induced in wet depressions for exchangeable magnesium is higher than the type of vegetation incidence burning grazing is calcium. This unbalance between calcium and where the of and light, litter (sample is extremely acid magnesium is not of sufficient magnitude to be the 6925) phosphorus of significance in agriculture, and it will be (pH 4-1) and the return of is low (68 is low, readily corrected by liming, which is needed on mg%), while the return of calcium very (19-4 The potassium is most of the soil types before intensive farming m.e.%). return of moderate low can succeed. to (2-25 m.e.%). (3) The analyses show a fairly uniform pattern of The litter under the various other kinds of soil fertility. The majority of the samples were vegetation induced as a result of more intensive collected from unfarmed and relatively un- burning and grazing is as follows: disturbed Thus sites. topsoils usually appear (i) Litter (sample 0923.\) from tall Cyathodes comparatively rich in phosphate and bases, a peaty robusta heath on the drier ridges sub- legacy from a long period of fertility-building jected to moderate burning and grazing is by natural vegetation. The subsoils, which, but the very acid (pH 4-6) shows a moderate to in the case of selective sampling of sort this low return of phosphate (75 mg%). The return give picture fertility, often a truer of soil are of calcium (61 m.e.%) and potassium (3-20 low in plant From mainly nutrients. these na.e.%) is moderate. it is obvious fertility analyses that the of the (ii) Litter (syple 6809A) under short Cyathodes which has been built over topsoil, up centitries, robusta (ad bracken fern communities, where may be lost very quickly if soils are the not burning andfrazing are more severe, is likewise given careful management, and once the top- very acid (pH 4-0) and returns a very low soil fertility has been lost farmer is faced the amount of phosphorus (41 mg%), and relat- fertiliser with the need to use to supply nutri- ively little calcium (26 m.e.%) and potassium his pasture plants. ents to 0.90 m.e.%) to the soil. (iii) Under bracken fern, in dry areas where burn- ing and grazing have been very severe, Litter Analyses the litter (sample 6808.1) is very acid (pH 4-0) and The analyses of various kinds of leaf litter are contains little phosphorus (30 mg%), calcium given in table 5. (19-0 m.e.%) or potassium (0-70 m.e.%). plant The highest return of nutrients to the soil (iv) Under a mixed rush, moss, and fern community is found in the litter of karaka trees (Corynocarpus, growing in moist depressions under fairly

56 grazing give poorer severe and occasional burning, the a slightly return to the soil than the litter (sample 6917) is very acid incleed original Dracophyllum forest. phosphorus (pH 3-7), and the return of (68 mg%) and potassium (1-20 m.e.%) is low and the return of calcium is very low Extended Legend

(10 m.e.%). in fokler fhe extentled legend supplied the These help provides of analyses to explain why the soil a summary of the chief characteristics potential fertility tends to be maintained under coastal the soil types and an estimate of their forest and they also show clearly that the different land use. It should be used as a supplementary grazing provided kinds of vegetation incluced by burning and legend to that on the soil map. REFERENCES

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H. W. I xile RRis 10 >(5:2 11 Development on Peat. N.Z. Soc. e I ds! ee 1 g r tlut 1 < N.Z. 182 pp. HUNT, F. 1866: ’Twenty-five Years Experience in New Zealand and the Chathams". William Lyon, Wellington. AIITH, S. P. 1911: The NIoriori People of the Chatham Islands. Alent. Polynes. Soc. 2: 207-18. HURsT, F. B. 1951: Climates Prevailing in the Yellow Grey Earth Yellow Brown Earth and Zones in New TAYLou, N. H.; SUTHERLAND, C. E. 1988: SOils of NUfth Soil Zealand. Sc/. TS: 1-10. Auckland. Proc. 14th N.Z. Grassl. Ass. Conf., pp. 25-38.

58 HAY, R. F.; MUTCH, A. R.; \VATTERS, \f. A. 1987: VANcouvER. G. 1798: "A Yoyage of Discovery to the Preliminary Report on Geology of Chatham North Pacific Ocean and Hound the World .Robinson, the the London. Islands. N.Z. Geological Survey Cyclostyled Report.

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IWilb: Soils of South Western Southland. N.Z. ]. -- 1953: Visit Chatham islands. 1)epartment of Sci. Tech. 33 (3): 33-75. -- .4 Agriculture, Christchurch.

WRicoll. A. C. S.; Alarsom A. J. (in press): Soils of Haoul Island. S.Z. Soil if ur. Bull. 10. i.,EA.11Y, 31. 191)!): The Zonal Peats of the Auckland Islands. Soil Bureau, Wellington. WRIGHT, A. C. S.; MILLER, R. 13. 1952: Soils of South-west Fiordland. N.Z. Soil lion Hull. 7. 31 pp. MADDEN, E. A. 19752. Report on investigations into I otentialities for Development of a Phormium Flax WRIGirr, A. C. S.; RicHARus, J.; Loss, W. R.; MILLER, the Industry in Chatham Islands. Department of R. B. 1952; Soils and Their Utilisation: Green Island- the Agriculture. Kaitungata 1.)istrict. N.Z. Soil Idur. Bull. G. 36 pp.

Nriv ZEALAND METEOROLOGICAL OFFICE 1947: The Chatham ISlands. N.Z. Alet. Office, 01 Dlate Of the 2. Niciv ZEALA.vo GovERNATENT, UNPUBLISHED DEPArrilENTAL REPORTS

HARRo.v. ]. U. 1952: Report on Forests and Timber WARD, W. T. 1954: The Soils of Stephen Island. Soil Future Chatham islands. State Supplies, Present and - 13ureau, Wellington. Forest Service Report.

Social PATTERSON, J. 1911: First Annual Report Resident CONNELL, R. P. 1938: Report on the Farming and Chatham Island. Department of Island and Economic Factors Allecting Farming in the Commissioner, Chatham Islands. Department of Agriculture Report. Territories, Wellington.

59 INDEX TO SOILS

Alvainunga peat, 50. Rangitibi hill soils, 47.

Awatapu steepland soils, 53. Rapunui loamy sand, 41. Hapupu sandy peat, 49. Rekobu - Awainunga complex, 52. peat, Hokopoi hill soils, 47. Tapuika 50. Tuku Te One loamy 40. Hokopoi - complex, 48. sand, Huro grey clay, 48. Te One loamy sand over peat, 40.

Huro grey clay and peaty clay loam, 48. Te One shallow loamy sand over basalt, 40. limestone, Huro mottled clay, 48. Te One shallow loamy sand over in.

Kahupiri shelly sand, 30. Te One shallow loamy sand over schist, 40.

Kairakau sand, 42. Te Whanga peaty loam, 53.

Kekerione sand, eroded complex, 40. Tiki brown clay, 43.

Mangahu clay loam, 45. Tiki brown clay, mottled phase, 44. phase, Mangahu clay loam, strongly rolling phase, to. Tiki brown clay, strongly rolling 43. Mangahu hill soils, 45. Tiki brown hill soils, 43.

Matarae peaty loam, 49. Tiki reddish brown clay, 44.

Mautere loamy peat, 50. Tiki reddish brown hill soils, 44.

Ohuku sandy clay, 39. Tuku hill soils, 46.

Pateriki peaty sandy 10am and loamy peat, 40. Tuku silty clay loam, 46.

Pukeraki Sne sandy loam, 43.

60 SOIL BUREAU PUBLICATIONS

D.S.I.R. Bulletins

Price

No. s. cl. IN HAMILTON 48 WATER-SUPPLIES OF FARMS AND DAIRY FACTORIES BASIN AND HAURAK1 LOWLAND. Taylor, N. H. 1935 I fi .. ..

fil SOILS AND AGRICULTURE OF WESTERN SAMOA Hamilton, W. M.; Grange, L. I. 1938 I 0 .. ..

OF 62 LAND DETERIORATION IN THE HEAVIER RAINFALL DISTRICTS NEW ZEALAND. Taylor, N. H. 1938 I 0 .. ..

(15 SOIL SURVEY OF DUVAUCHELLE BAY -WAINUI DISTRICT, BANKS PENINSULA. Harris, C. S.; Harris, A. C. 1939 I 3 .. ..

(Hi A SURVEY OF TUNG GROVES IN NEW ZEALAND. N. H.; Dixon, J. K.; Hodgson, L. 1939 2 0 Burns, M. M.; Taylor, .. ..

70 LAND UTILISATION REPORT OF THE HERETAUNGA PLAINS. print 1939 Out of .. ..

71 SOIL SURVEY OF WESTPORT DISTRICT. Harris, C. S.; Harris, A. C. 1939 I fi .. ..

72 SOIL SURVEY OF WAIRAU PLAINS, MARLBOROUGH. S.; Birrell, K. S. I939 2 0 Harris, C. .. ..

COUNTY. 76 SOILS AND AGRICULTUIRE OF PART OF WAlPA print Grange, L. I.; Taylor, N. H.; and others. 1939 Out of .. ..

NEW ZEALAND, WITH 77 MAINTENANCE OF VEGETATION COVER IN SPECIAL REFERENCE TO LAND EROSION. Out of print 1939 ’ .. ..

92 SOIL EROSION IN THE HIGH COUNTRY OF THE SOUTH ISLAND. J. D.; Dixon, J. K.; Metson, A. J. 1945 3 0 Gibbs, H. S.; Raesicle, .. ..

OF MID-HAWKE’S 94 SOIL AND SOME RELATED AGRICULTERAL ASPECTS BAY. Pohlen, J. J. anti others. 1947 0 0 . . ..

121 BOTANICAL SURVEY OF AN EXPERIMENTAL CATCHMENT, TAITA, NEW ZEALAND. Druce, A. P. 1957 la n . ..

130 THE EARTHWORM FAUNA OF NEW ZEALAND. Lee, K. E. 1959 tic 0 . . .

61