Soils of the Lower Burdekin River- Barratta Creek-Haughton River Area, North Queensland

Queensland Government Technical Report

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For information about this report contact [email protected] Agricultural Chemistry Branch Technical Report No. 22

.. -~. o

SOILS OF THE LOWER BURDEKIN RIVER- BARRATTA CREEK-HAUGHTON RIVER AREA, NORTH QUEENSLAND

R.E. Reid and D.E. Baker

Agricultural Chemistry Branch

Queensland Department of Primary Industries Brisbane 1984 .

,, CONTENTS

Page

ABSTRACT (i)

PART A - COMPENDIUM Summ~y of Soil and Land Use Chamacteristics

I. INTRODUCTION 1

•

PART B - DETAILED REPORT

2. INTRODUCTION 9

2.1 Historical 9 2.2 Purpose and Extent of Survey 9

3. SOIL SURVEY METHOD 10

3.1 General i0 3.2 Soil Profile Class and Mapping Unit Derivations II 3.2.; Soil profilz class iI 3.2.2 Mapping units I~

4. PHYSICAL ENVIRONMENT ii

4.1 Climate II 4.1.; Gen~£ I~ 4. I .2 Rainfall distribution Ii

4.2 Geology and Geomorphology 12 4.2. ~ G£n~ta£ 12 4.2.2 G£oZogy 12 4.2.3 Fluvial g£omorphology 12 4.2.4 Classification and descriplion o~ topographic 18 forms

4.3 Hydrology 21 4.3o I Surfac~ ~drology 21 4.3.2 Subsurface hydrology 22

4.4 Natural Vegetation 24

5. SOILS - CLASSIFICATION AND MORPHOLOGY 2Z

5.1 General 27 5.2 Morphology 27 5.3 Mapping Units 27 5.4 Soil Variability in i:I00 000 Mapping Units 27

6. CHEMICAL AND PHYSICAL CHARACTERISTICS OF THE SOILS 43

6.1 Introduction 43 6.2 pH 44 6.3 Salinity 45 6.4 Cation Exchange Capacity, Exchangeable Cations 47 and Base Saturation Pa$e

6.5 Sodicity and Dispersion 51 6.6 Plant Available Water Capacity 53 6.7 Clay and Clay Activity Ratio 55 6.8 Total-P and K 56 6.9 Extractable Phosphorus 57 6.10 Carbon, Nitrogen and Sulphur 59 6.11 Trace Elements 61 6.12 Properties of Gilga± Soils 62

7. AGRICULTURAL LAND USE 64

7.1 Present Land Use 64 7. I . ; Irrigated 64 7.1.2 Dry land 64

7.2 Changes with Increased Availability of Zrrigation Water 64 7.3 Environmental Limits to Irrigation 65 7.3. I C/J~e 65 7.3.2 Topography 65 7.3.3 Surface drainage 66 7.3.4 Subsurface d~ainage 66 7.3.5 Flooding 68 7.3.6 Soils 68

7.4 Crop Suitability and Management 69 7.5 Land Capability Classification 69 7.6 Estimated Sugar Cane Yields 70

8. ENGINEERING CONSIDERATIONS 70

8.1 General 70 8.2 Expansive Clays 72 8.3 Highly Dispersive Clays 72 8.4 Corrosion of Underground Services 72 8.5 Soil Permeability 73 8.6 Flooding and Drainage 73 8.7 Potentially Useful Deposits 74

9. ACKNOWLEDGEMENTS 74 .

I0. GLOSSARY 74 ii. REFERENCES 75

APPENDICES

1. Vegetation - Common and Botanical Names 80

2. Relationships between Soil Profile Classes and Soil 82 Series (Hubble and Thompson 1953)

3. Conventions used in the Description of the Morphology 84 of Soil Profile Classes (Table 5.1)

4. 1:25 000 Reference Area Mapping Unit Composition 86 Pa~e

5. Morphological and Analytical Data for Representative 87 Soil Profiles

6. Classification of Profiles Sampled for Detailed 114 Analysis

7. Land Capability Classification Schemes 117

LIST OF FIGURES

Figure No. Page

2.1 Locality plan. i0

4.1 Approximate area flooded to greater than 15 cm 23 in February 1978.

6.2 a Soil pH profiles (clays). 45 b Soil pH profiles (duplex soils). 45

6.3 a Chloride profiles (cracking clays). 47 b Chloride profiles (dupex soils). 47

6.4 a Calcium Magnesium, Sodium and CEC for soil g~u~ A' 49 b Calcium Magnesium, Sodium and CEC fo~ soil group B 49 c Calcium Magnesium, Sodium and CEC for soil group C 50 d Calcium Magnesium, Sodium and CEC for soil group D 50 e Calcium Magnesium, Sodium and CEC for soil group E 50 f Calcium Magnesium, Sodium and CEC for soil group F 50 g Calcium Magnesium, Sodium and CEC for soil group G 51

6.5 a Exchangeable sodium percentage profiles (clays). 51 b Exchangeable sodium percentage profiles (duplex soils). 51

6.7 a Clay percentage profiles (clays). 55 b Clay percentage profiles (duplex soils) 55 c Clay percentage profiles (other duplex). 55

6.8 a Total phosphorus profiles (clays) 58 b Total phosphorus profiles (duplex soils). 58 c Total phosphorus profiles (other duplex). 58

6.8 d Total potassium profiles (clays). 58 e Total potassium profiles (duplex soils). 58 f Total potassium profiles (other duplex). 58

6.12 a Soil pH for mound and depression profiles. 63 b Soil EC for mound and depression profiles. 63 c Soil Clay % for mound and depression profiles. 63 d CEC/Clay % for mound and depression profiles. 63 LIST OF TABLES

Table No. Page

I.I Major distinguishing morphological and topographic 2 features of the soils.

1.2 Soil limitations, crop suitability and management 4 problems.

1.3 Soil limitations to engineering works. 6

1.4 Irrigated land capability classification of I:i00 000 7 mapping units.

1.5 Ratings for chloride, sodicity and nutrients in the 8 sampled soil profile classes.

4.1 Climatic data s~mmary for Ayr, Clare, Giru and 13 Woodhouse.

4.2 Postulated chronology of alluvial landscape 17 development.

5.1 A description of the morphology, topography and 28 vegetation of the soil profile classes.

5.2 i:i00 000 mapping unit composition. 42

6.1 a Groupings of sampled soil profile classes and extent 43 of analyses performed on each.

b Summary of mean values or ratings of laboratory 44 measured attributes in surface (0-I0 cm) and two subsurface (50-60~ 140-150 cm) segments of soil profile class groupings A to G inclusive.

6.2 Mean laboratory pH values and standard deviations 45 at five depths for seven groups (results expressed on a 40°C air dry basis).

6.3 a Mean values of electrical conductivity (mScm -I ) over 46 five depth intervals for seven soil profile class groupings (results expressed on a 40"C air dry basis). b Linear functions and coefficients of determination 46 (r 2) for relations between chloride (CI; %) and electrical conductivity (EC; mScm -I ) for seven soil profile class groupings where the model has the form EC = a + b CI.

6.4 a Calcium/CEC ratios, magnesium/CEC ratios, sodium/CEC 48 ratios and base saturation for seven soil profile class groupings and two depths (results expressed on a I05°C oven dry basis). b Mean values and standard deviations for exchangeable 49 potassium at four depths for seven soil profile class groupings and the ratio of extractable to exchangeable potassium in the 0-I0 cm profile segment of these soils (results expressed on a I05°C oven dry basis). Table No. Page

6.5 a Mean values and standard deviations for dispersion 52 ratios (R I ) for seven profile class groupings and four depths (results expressed on a I05°C oven dry basis). b Amount of exchangeable Na present when ESP = i, 53 and calculated gypsum requirements to reduce ESP by 1 unit at 50-60 cm for profile class groupings with high subsoil ESP's.

6.6 Average PAWC by two different methods, average 54 rooting depth and days between irrigations for soil groups A to G.

6.7 Clay activity ratios (CEC g-1 of clay) for seven 56 soil profile class groupings and three depths.

• 6.8 Mean total-P levels (%; I05°C oven dry) and 57 standard deviations at five depth intervals for seven soil profile class groupings.

6.9 Mean acid and bicarbonate-extractable phosphorus 59 levels and standard deviations at 0-I0 and 10-20 cm for profile class groups A to G (results expressed on a 40°C air dry basis).

6.10 a Mean values and standard deviations for organic 60 carbon and total-N at two depths for seven profile class groupings and mean C/N ratios for surface horizons of the same soils (results expressed on a I05°C oven dry basis).

b Mean values and standard deviations of total S at 60 two depths and C:N:S ratios in surface (0-I0 cm) samples for seven profile class groupings (results expressed on a I05°C oven dry basis).

6.11 Mean values and standard deviations of DTPA 61 extractable copper, zinc, manganese and iron for surface (O-10 cm) samples of seven soil profile class groupings (results expressed on a 40°C air dry basis).

7.1 Water quality, northern left bank area. 67

7.~ Areas of each land class from i:I00 000 mapping 70 units.

7.3 Estimated sugar cane yields, suitability ranking and 71 limiting factors for l:100 000 mapping units.

LIST OF PLATES

Plate Page

A Light coloured deposits of fine sand on parts of 16 a 6 Umb mapping unit (cleared) at AMG Zone 55K: 512200 E, 7838150 N after flooding in February, 1978.

B Flood water covering Bruce Highway in mapping unit 22 2 Ugd at AMG Zone 55K: 527900 E, 7837200 N in February, 1978.

C. Soil profile class 2 Ddb carrying cabbage gum, 25 carbeen, spear grass and purple top chloris. AMG Zone 55K: 518900 E, 781Z300 N. Pla~e ~age

D Soil profile class 6 Dyg carrying beefwood, popla~ 25 gum, carbeen and spear grass in foreground. Soil profile class 6 Dya carrying popla~ gum, grey bloodwood, cockatoo apple, giant spear grass and spear grass in background. AMG Zone 55K: 520100 E, 781557O N.

E Soil profile class 6 Dyd carrying poplar gum, grey 26 bloodwood, carbeen, giant spear g~ass and spear grass. AMG Zone 55K: 515750 E, 7817800 N.

F Flood damage to Clsme-Giru tram line at AMG Zone 55K: 73 513250 E, 7822900 N in February, 1978. ABSTRACT

A I:I00 000 soil survey was carried out of approximately 80 000 ha between the Burdekin and Haughton rivers in north Queensland. A 3 740 ha reference area, the Burdekin Rural Education Centre, was also surveyed at 1:25 000.

Part A of this report is a compendi~um while Part B sets out full details of soil survey method, physical environment, soil classification and morphology, soil chemical and physical propertiea, agricultural land use and engineering considerations.

The area was divided into the following topographic forms:

1 - Local alluvial - colluvial plains (3 soil profile classes).

• . 2 - Major river flood plains (17 soil profile classes).

4 - Dissected uplands and outwash plains developed from acid intrusives (7 soil profile classes).

5 - Dissected uplands on intermediate intrusives (3 soil profile classes).

. 6 - MiscellaneoUs alluvial deposits (23 soil profile classes).

The majority of the area is occupied by cracking clay and solodic-solodized solonetz soils of topographic forms 2 and 6.

An irrigated land capability classification for crops other than rice has been given for the mapping units. There is no class i land, 12 477 ha of class 2 land, 45 445 ha of class 3 land, 16 114 ha of class 4 land and 1 532 ha of class 5 land. Because paddy ri6e requires different soil characteristics to other crops, a separate land capability classifi- •cation for rice was used giving 15 837 ha of class 1 land, 12 949 ha of class 2 land, 15 145 ha of class 3 land, 12 832 ha of class 4 land, 18 805 ha of class 5 land. PART A

COMPENDIUM

• SUMMARY OF SOIL AND LAND USE CHARACTERISTICS ..

i. INTRODUCTION

This compendium presents material of use to those requiring summaries of the information relevant to land use and development potential of the soils of the survey area.

The information is given in the following Tables:

Table 1.1 Major distinguishing morphological and topographic features of the soils.

Table 1.2 Soil limitations, crop suitability and management problems.

Table 1.3 Soil limitations to engineering works.

Table Io4 Irrigated land capability classification of 1:100 000 mapping units.

Table 1.5 Ratings for chloride, sodicity and nutrients for the sampled soil profile classes.

Tables 1.I and 1.5 refer to all identified soil profile classes and all soil profile classes sampled for detailed analysis respectively, while the remaining Tables refer to the l:lO0 000 mapping units. - 2 -

1 • - TABL~ l.i

#~or ~:~g~4 mo~o~g~:4~ ~d ~apogr-::~h~c ~e~:~.~ o~ ~ ~o~a

$o~i profile ~a)or ~tst~nguLs01n~ features Soil name Topographic form Subdtvls~on class*

I ~ge* L~nearly Btlgaied grey-brown c!ay~, a~kaline soll L~nearlv g~!ga~ed grey- Local a~luvlal- ~-3% ~looe areaa tame=ion trend** brown clays =olluvtal pla~n~

1 Dba ° 5-15 cm clay loam over extremely hard eedium clay Grey-brown and b¢o',¢~ [i) 51lghtly elevated areas w~th solodios-~olodlzed

~ Ugd Mottled bleached grey light or Light ~edlum cracklns 8leached grey :lays Malor river flood Low lylng areas with

2 Ugf Mottled grey medium or heavy :racklng :lays, usually Grey clays (2) strongly alkaline by 120-i50 cm

~ Dye Grey duplex soils with med%,.on textured'" A horizon Gi~galed solodlcs- lO to 25 cm deep, alkaline soll :eactlon trend solodlzed solonetz

2 ~ge Mottled Brey and /ark !zgh~ or i~Kht med~ cracking Grey and dark clays Depression and ~ra~nage clays, strongly alkaline by 50 am i~nes with 0.2-0.5~ slope

2 Ugg Mottled grey medium or heavy crackin s clays, ~troft~iy Grey =lays alkallne by ~0-90 cm

2 Ugh Mottled grey a.d dark m~lum or heavy :racklng clays, Grey and dark c lays $11ghtly elevated cl~y s~rongly alkallne by 30 ¢m pla~ns~ <0.5~ SlOpe

2 Usi -~ole ¢oloured grey medlumor heavy crackln~ clays. Linearly gl!gaied clay- Areas wltO >1% slope iMound) strongly alkaline at the surface solod~c-solodlzed solonetz complex 2 Ddc Dark duplex soils wtth silty clay loam & hor%zon 15 to ". (Depression) 25 ;m deep and alkal£ne soil reec~lon trend

• ~ Dbc Brown duplex soils with medlum textured A horizon ~0 $olodlcs-solodlzed Slightly elevated areas and . to 25 cm deep, strongly alkaline by 90-120 cm solonetz some Levee back slopes, <0.9~ slope 2 Dbd ~rown duplex soils with medium textured A horizon 20 to 35 cm deep, strongly alkaline by 60 ¢m

2 Dbe grown duplex soils with medium textured A horizon 12 to 20 :m deep, strongly alkaline by 90-120 cm

2 Dbf Brown duplex soils wi~h coarse texcured~ a horlzon 12 to 2~ cm deep, strongly alkallne by ~0 cm

2 Dyb Grey and dark duplex so,is w~th medium textured A horizon i~ to ZOcm deep, stron~iy alkaline by 60 am

2 Dda Dark duplex soils with medi,~m textured A horlzon 2.5 :o 12 cm deep, stron~ly alkaline by 60-90 cm

2 9db Dark and ~rey duplex soils with ,~e~ium tex:ured a horizon 2.~ tO 12 om deep, strongly alkaline ':y 30 Cm

2 Ugl Mottled bleached grey and dark ilgnt or light medl~m Grey clays Areas under laln by conttas- cracking clays wiLh alkaline sOil reaction trend, tin S materials) <0.5% slope Under!aln by coarse or medium textured material or cat clay by I00-150 :m

Z Ddd Dack duplex soils with meditu~ textured A horizon from So lodlcs-solodized I0 to 25 cm deep, alkaline soil reaction trend, sotonetz Underlain by :oarse or medlum textured material or cat clay by !00-150 cm

4 Ucb Uniform deep coarse sendl with a pall ^2 horizon Deep sands Dissected uplands Upper slope and ~id slope and acid or neutral soil reaction trend and outwash plains positions, 1-5% slope developed from 4 Uce x gleached uniform :parse ~ends overlying silcrece 8leached sands over- acid tntrusives pans at ~O-lOO cm, acid or neutral soll reaction [ylng • pan (&) trend

& Dyd x Yellow duplex soils with coarse textured A horizon Acld and neutral yellow ~0 to 90 cm deep, acid or neutral soll reaction duplex soils trend

" Gnb Red ltructurad gradatlonal sOiiS with coarse Red podzoll¢ SOilS textured A horizon 70 to 90 cm deep, acid or neutral loll ~elction trend

~ UCC B|eached uniform coarse sands with A horizon 40 CO Deep bleached sands Lower slope po~Itlon, l-&~ 90 cm .deep, acid or neutral soil reaction trend slope

& Dyj x Grey, yellow and brown duplex soils with coarse S~lodics-solodlzed Dralnase lines and mld-slope ~extured A horizon 60 to 80 cm deep, alkaline solonetz positions, i-5% slope soll reaction ~rend

~ Dge Gleyed duplex soils with coarse textured a horizon Gleyed duplex soils 30 tO 70 cm deep) acid Or neutral SOil ~eaotloa trend

~ Dra ° R~d duplex sozls ~ith fine sandy clay loam A horizon Neutral red ~uplex O~ssected uplands Upper slope positions~ i-~% 15 =o 25 =m deep, neutral soll reaction trend soils on tntermedlate slop~ ln~live$ ~ Dye* Grey duplex soils with ~dium textured A horizon 15 Grey solodics-solodize~ Lower slope posltlon~, ~-~ ~0 ~5 cm deep, alkallne soil ~eac~on trend solonetz (~) slope

5 Dye YeLlow duplex soils wl~h ~end7 clay loa~ A horizon 15 Neutral and alkaline No fixed slope poeltio~, to 30 cm deep, neutral or alkaline soll reaction yellow duplex soils i-5% slope trend - 3 -

:ABL~ ~.i ~ .... ~:~nc~c~ ~c~:h~c:~ ::d :~zo~r.~r'.j fec:~re~ ?~ :ce 3C~& ~Dn:.

Soll profile Major d[$t~nguishlfl~ features Soll name Topo~raphlc form Suba~vls~on c~ass

6 ~h~a+ ~ntfor~ f~ne ~andy loam =o fine ~andy c~ay loam ~o~a, Un~or~ai~uvta~ so,is Miscellaneous Soils ¢onflned to pre~ent acid or neutra~ so~[ reaction trenC al~uvcal deposits ~urdek~n ~:ver ~evee ~eoos- L~s, 0-Z% ~Lope 6 Gna* Bro~.~radat~ona! so~Ls w~th ~ed~u~ :exture~ A horizon, Grada~!onal soils (5~ neutral or a~kal~ne soil reaction ~rend

6 Gnd Ye!!ow and brow~ ~radat!onal so,is w~t~ :oar~e textured A horizon, neutral ~oi~ reaction ~:and

6 Dbb + ~vo~ duplex ~olls wltn aedLu~ textured A hOri%on 3~ to Solodic: ~0 cm deap, ~ika/~e ~oil reaction :rend

6 U~ Srown unl~or~ ~d¢~ :extured so~ with A ~or;zon ~0 Un~or~ alluvia! so~l~ Recent Hau~h~on ~lver Co 60 c~ deep, neutra~ or a~ka~e so~L reaction ~ren~ alluvial Oepo~cs, 0-3% siope 6 Dbc Bro~ duplex $o~ls w1~h medium or occasionally :oarse ~rey-bro~ podzo[~c textured A horizon ZO ~o 4O cm deep, neutral sot~ sofia reaction ~rend. Overlies :edl~ or coarse :extured ~erzal ~t 90-150 cm

5 Dbd B~own duplex soils w~h me~ or occas~onally :oarse ~[odi~s-solodized ~extured A horizon 20 to ~0 :m deep, alkaline soll solonetz xx reaction ~rend. Overlies ~edi'am or coarse ~extured ~terial at 90-150 cm

6 Dbe Bro~ duplex so,is w~th medium or occasional[ 7 coarse textured A horizon i0 ~o 2Q cm deeD, alkailse so~i reaction ~r~nd. Overlies medi~ ot ~3arse textured ~erlal a~ 90-150 cm

6 Ufd Dark non-crack~n s clays wi:h acid or neu~ra~ so~l Non-crackln~ clay Minor Batavia Creek al[u- reaction trend. Overi:es sand ac 70-150 cm alluvial soils v%a~ deposits, 0-~% ~iope

5 Dyh Grey ~uplex soils with coarse textured A horizon 20 [o Grey solod~cs-solodlze~ 50 cm deep, a[kallne soll reactlon ~ren~ solonetz

6 Ucb Gre~ or bro~ unlfo~ coarse ~ex~ured soils wl~a D~p sands Miscel~aneous O~her a~luvlal deposits, conspicuously 51eached or occasionally pale A2 hor%zon, alluvial ~epo~i~s 0-~ slope acid or neutral soll reactlon trend <~)

6 Gnb Red and bro~ struccured %reds[tonal SO kis with Coarse Red ~odzo[~c solis textured A horizon 70 to i20 ~m d~a~, a~d or ~eqtral soil reaction ~rend

~ Gnc Yellow ~ructured %cada~ional or occasionally duplex Grada~ional solls so%l~ wlth med~,~ textured A horizon [5 ~o &O cm deep, alkaline soil reaction trend

6 Dra Red duplex soils with coarse ~extured A hor:zon ~0 ~o Red p~zolic Soils 50 cm deep, ~cid or neutral soll reaction trend

~ Orb Red duplex SO~lS w~h medium tex:ured A horizon ~O tO ~5 cm deep, acid or neutral soll reaction trend

6 Dye Yellow duplex soils with coarse textured A horizon 60 Yellow p~zollc soils tO 1~0 Cm deep, acid Or neutral ~otl reaction ~rand

6 Dyb Yellow dup!ex soils w~th coarse textured A horizon 30 to 50 co deep, acid ~o neutrel soi[ reach!on trend

6 Dye Ye~[~ duplex soils wlt~ ~dium textured A horizon &5 ~o ~0 cm deep, ac&d or neutral so~l :eactton trend

6 Dyd Yeliow duplex so,Is w~th ~di'~ textured A horizon 20 to ~0 cm deep, acid or neutral so¢l reactzon trend

6 Ore Red duplex soils with eed%um textured A horizon ~0 :o ~lod~cs-solodized 50 cm dee~, a~kalLn~ so~ reactlon trend solonetz

6 Dye Yellow duplex so,is with coarse textured A nor%zon ~0 ~o ~0 cm deep, alkaline soll reaction trend

6 Dyf Grey, ye~low and brown duplex SOt!S with medi~ textured A horizon 25 :o ~0 zm deed alkaline so~l read,ion trend

~ Dy~ Grey and bro~ dup!lx soils with ~edz~ [extured A horizon i0 tO 20 ¢m dee~. alkailne sO~i reack~on trend

* The soll profile class names are derlved as per the followlnS example. 2 Ugd: 2 ~nd~cate~ the toposraphlc form (In this case, major river flood plain3), US ~ndlcates t~e primary profile ~orm subd~vlslon of North¢o~e (19~), ~a uniform, fln~ textured, se~-unall 7 crackln S soil) and d di~tln~u~shes thls soil profile ~lass from others of the flood plain with uniform, ~ne textured, ~easonaLly ~ack~n~ profiles hut wi:h important differences in some o~ner properties.

Thompson (19~). .. Northcote (1979).

+ ~oll Survey St~f ~1951).

x ~.P. Thompson ~npu0iished ~a~a).

xx ~hese soll ~rouos were :la~a a~ ~olodic~-~olod~zed ~otonecz on t~e 5asi~ of thelr ~oll rea~tlon trend~, bleached ~ horlzons~ ~e~er~L 7 ~brup~ bou~dar~e~ to ~ne uppe~ 'B horizon~ a~d the ~ener~ly prt~matl¢ st=uc~ure o~ ~e uppe~ ~ horizons. Analytical data ~ndi~ate~ that they ~ay be better considered as ted-bco~ e~r ~hs. - 4 -

TABSE 1.2

SCS& ~.S~=~O.S, ~.~op 8u%~abs~sC~ :~d ~m~gem~nt prob~8.

So~l ~ro~p ~ ii~a~on~ Lzke[y speclf~c ~hys~ca~ Ch~ical C~op ~ui~ab~i~y ~na~emen~ problems i ~e Kros~on Low ~enera~ fer:illty Cane. kena~, elephant ~rass, S~ope Poor soll - seed contact Med&~ ~o h~h sal~ levels cereals and oil seeds Wet season harves~zn~ ~erEence i Dba, b &heat erosion L~ ~eseral ferti~zty ~tce Res tricted r~tin~ depth and p~ant Impermeable upper ~ horizon Medium to h~%h sal~ levels Suit~ to anne. kenaf and available water Surface crus~n~ be!ow 3C-70 am elephant ~rass only after $0~I variability deep rippin s and &ypsum . 2 Usd Flo~n~ 5~ general ~ert~[~ty Rice, cane, kenaf, elephant Surface dra ~na~e and water- 2 Dy~ ~ck of sZope and wa~er[ogg[n~ ~rals, soybeans, careers and logSln s G~l%al ~o 70 cm deep oL] ~ee~s ~ec season harves~n~ P~r soil - seen con~a¢~ 5~er~ence Narrow critical ~otstur~ range for cultlva~ion

2 ~. ~ Fioodln~ ~w %~nmra[ fertl!ity ~Ice, cane, kena~, e[ephan~ Surface drainage and wate~- Water~oggzn% grass, soybeans, retells and ~ogglng Giigaz to 50 ¢m deep o%~ seeds Wet season harvest~n~ P~r sol! - seed con~acE K~rgen~e very narrow Critical ~/stu~e range for cultivation

Z U~e FLoodln 8 ~w ~en~ral ferti~i~ 7 Rice. cane, ken~f, elephan: waterlo~s~n8 ~aterlo~in~ Medz~ sa[~ levels below ~rass, ~oybeans, cereals and Wet season herren tt~ G~l~al to 30 cm deep &O-50 cm oil seeds ~r~ence P~r soll - seed contac~ Narrow cr~ca~ ~zsture range for cultivation

~ ~h F~o~[n~ L~ 8enera~ ~ertillty Rice, cane, kenaf~ elephant Nutrten~ ~mba~ances ~7 cause Water~o~n~ Exposurm of alkaline ~er!al ~rass, soybeans, cereals and uneven ~ce ~row~h G&i~al to 30 Cm deep O. mounds a~ levellln~ ~y oll seeds Waterlo~gzn ~ P~r so&! - seed contac~ cause nutrient imbalances Wet season harvestln~ ~r~ence Very narrow crltlca[ ~sture rans~ fo~ cu~vatlon

2 ~C Shee~ erosion tow ~emer/l fer~illt 7 ~e I kenaf, elephant 8rags. Slope P~r ~oli - seed contact H~h salt levels below 30 cm soybeans, cereals and o&[ ~rEence ~il vartabi[zty between ~und on mounds seeds Restricted rootln~ depth and and depress%on ~posure o~ alkai~ne ~terial pian~ available water on ~unds a~ leve[izn~ ~ay Very narr~ cr~tlcal M~sturi cause nu~rlen~ Imbalance~ range fo~ cul~[va~ion

2 Dbc, d F!~dlng Low ~eneral fertlll ty ~e.

2 Dbe Flood%n s Low ~eneral far.flit 7 Rice, c~ne,'kenaf, elephant ~aterloE~ins 2 Dbf Wa~erlogg&ng Medi~ ~o hzgh sm[~ levels ~rass. soybelns, cereals and ~et season harvestln~ 2 Dyb Impermeable upper B horzzon below 30-60 am o&l seeds ~rsence Crus t/n~ Res trlc=~ rootin~ depth and p~ant available water

2 Dda, b Fl~/ng ~w ~enera~ far:linty Rice Wateriogg~n~ Waterlo88~n ~ Medium to h~n ~alt levels Wet season harves~in 8 Cr~l~tn~ below 20-60 cm ~rsence impermeable u~er ~ horizon ~es~icted r~tln~ depth and plant avallabie w.tar D~p r~ppln s and gypsum may be seeded before srowln 8 crops other :hen rice

2 u~ Flo~in~ i~ ~eneral ~er:ili ~y None where profiles overlie Surface drainage and water- Waterlogg~n s cat ¢!ay ~o~g~ng 2 Ddd Wa~er tables o~ their likely H~sh salt levels below %%ere profile overi~es sandy Wet season harvesting deve[op~n~ ZO-60 cm ~ter~a[, cane, ~enaf, soy- ~rsence beans, cereals a Dyd, J Erosion Low ~eneral ~er~lli~? Tree crops only ~Iope & O~a ~w water retention proper t~es ~pray or trlckle Irri~at~on ~ Ucb. z, e Water tables below 50-i00 cm ~nly

& Gnb ~osion i~general fertility Any hor=%cu!turai crops Slope ~deta~e water retention ~d cassava 5pray or tri:kla Irr~atlon only Ciearln s ~nd/or irrigation ~y cause d~ slope seepage problems Nematodes (suscept~bie crops only)

5 9ra £roszon L~ general fert~lity All crops except ~ice SLope Stone and cock outccops Cleartn~ and/or irrigation ~y So*l vartabziLty cause ~o~ slope seepage Surface crusting

5 Dye Erosion ~ general ~ertility All crop~ excep~ r~ce Slope Wacerlog~In8 Positions in landscape ~Ke C~ustin~ ~na~e~n~ with 5 Dra nece~sar 7 ~mper~abie upper 8 horizon but y~elds w~l be Z0-50~ ~ower

5 Dye Ero~tofl ~w genera~ fertility Cane, kena~, elephant ~rass, Slope Stone and rock outcrops soybeans, cereals and oil Clearln 8 and/or irr~a~ion ~y Sozl variability seeds cause d~ slope seepage impermeable upper B horizon Surface crusting - 5 -

TASLE !.2 So~t ivm:ccz~o~s, vroc su~$abtlv~9 ar~ ~anag~menr ircb!zms co~:.

Soll ~roup Soll l!m[ta~ons L~ke~y ~pe¢if~ Physical Chemxcal Crop sut~bxl~ty ~na~ement problems

6 Uma $ozl vartablILty ~some areas Low ~eneral fertt lily ~i~ crops except rice ~r~ence ~ Drb. ~ Dye, d, 6 Gna, ~ only) Preference ~hould probably 6 bbc ) 6 Dra, b Crusttn@ (some ~reas of 5 Drb, be given to small crops on Nematodes ~susceptible crops b Dyb, c. d 6 Dye. d a~d 6 Dbc only) 5 Oyb and 6 Dra only on 6 Dra and ~ Dyb) 6 Dbc

5 Ufd F~oodtn~ Low ~eneral fertt~lty Pastures only Should calry ~ood ~ras$ cover 6 Dyh Water~o~i~ over ~hewet season ~0 prevenz Erosion erosion

~ Umb ~loodtn~ P~obable low to .~oder&~e All ~rops excep~ rice ~rgence Crus~n~ ~where s~r~ce ~enera~ ~e~£~tty ~ex~ure ~s fzne sand~)

6 Dbb Cresttn@ (where surface Moderate Bene{a~ ~e~ttltzy AI~ Crops ex~ep~ ~Lce ~c~eoce ~ Dbd, e textures ~re ~tne sandy) Possible moderate to low salt Possible restricted roottn& leve~ b~!ow 60-120 :m depth and plan~ available wate~

5 Dye Soll varzabxl:~7 Low ~necal fer~itl~y AIL crops excep~ rtc~ Wa~rlo~gtng below ~0-70 cm ~y 6 Ucb Natetlo~g~n& due :o water cause problems wlth some cropa perched on B horizon N~ete surface textures t~ ~tghter than coarse sandy ~oam, spray or ~rtckte irrigation ~ay be needed Ne~odes (suscep~tbte crops only)

6 Gab No ~a~or problem ~w ~enera£ ~er~ttt~ All crops exce~ rice, Nematodes Csuscep~ibie crops only} preference should be ~£ven to s~l~ crops

6 GAC S~nk hole mlcrorel%ef Low general fer~%l[~y Pastures only Dlspers~ve ~or%zon ~y preven~ Soil variability High sa~ ~eve~s below =raffic after [rrxga~xon or ra:.n Dispersive horizon presa~t ~O-gO =~

6 Dec " Soil v~r~ab~l~t 7 Low ~eneral fer:iltty Cane, kenaf, elephant ~rass', ~ergence 6 Dye, ~ ~mpe~eable upper 5 horizon ~w to moderate sai~ ~eve[s soybeans, :ereals and o~i Restrtc ted :oo~In~ de~ and Crus~tn~ (where surface ~ex~ure below 60-120 cm seeds pkant avaxlable wa~er is fi~e sandy)

6 Dy 8 Crustln~ Low ~eneral ferti~ =~e, kenaf, e[eDnanK ~rass, ~er~ence l~ermeable up@at B horizon Moderate sa It levels below soybeans, cereals and oil Waterlo~sln E Wa~erLo~kn~ 60-90 ca seeds Restricted ~ootln~ depth and plan~ available water ._ ~era posed%on dictates ~anaKe- ~ent w£th other sok~s of topo- gra~hxc for~ 6. deep rzppkng and gyps~ may be needed - 6 -

TABLE 1.3

So~ :~gu~C~s ~o ~g:~e~g ~o~s

~%l group Gilgai Presence of expansive D~spersion Likely :orr0s~on of Surface Internal Fiood~nB zLay underBround dra~saBe drainage serv%ces i Cge Weak Throughout Moderate to high Nigh below 90 cm ~ood 51ow ~one below 90 cm i Dba, b None Subsoil may be Moderate to high High below 60 cm Good Very slow None expansive th=oughout

~ Ugd, f Moderate Throughout Moderate to h~gh Possibly hiBh below Very poor Slow Frequent bekow 30 c~ 90 cm

. _ . 2 Dye Moderate Subsoxl expansive Moderate to hiBh Nigh below 90 ~m Very poor Slow Frequent throughout

Z Uge, g Moderate Throughou~ Moderate to h~gh Nigh below 60 cm Poor Slow Occasional ~o stron8 below 30 cm

2 UBh ModeraZe Throughou~ Moderate to hzgh N~gh below 30 Cm, Poor Slow Occas[ona! below 30 c~ gypsum may occur

2 Dd¢ - Weak Subsoil in depression Mc~lerate to high High below 30 Cm Goo~ Slow Rare 2 UBI throughout mound uhrougnout 2 Dbc None Subsoil may be Moderate to high NiBh below 90 cm Moderate Very slow Rare expensive throughout

2 Dbd, f None Subso~l may be Moderate ~o high Nigh below 30 cm, Moderate Very slow Rare Z Dyb expansive Chroughou~ gypsum may occur

2 Dda, b None Subsoil probably Moderate ~o high Nigh below 20 zm, Moderate ~xtre~ly Rare expansive throughout gypstu~ ~y occur

Z UB~ Moderate Throughout ..~Oderate to high N~gh below 30 cm, Root Slow and wa~er F=equenK below ~0 cm gyps~ ,~y occur tables may develop in matertal below

2 Ddd None Subsoil may be Moderate ~o high NIBb below ]0 cm, Moderate Slow and water Frequent expansxve below 30 cm gypsum may occur tables may develop ~n ma~er~al below

4 Ucb, ~ Grab None ~ne Low ~hrouBhout Low Good Very rap:d None

~ Ucc, e None None Low throughout Low Good Very rap%d but wa~er None table~ may develop w Dyd None None Low throughout Low Good Rapid None

& 9y], 4 Dga None None Low throughout Low Good Moderate None

5 Dra None ~.e Low throughout Low Good Rap~d None

5 Dye None None Nigh throughout Nxgh below &~ =m Go~d Slow None

5 Dye None None Moderate ~hroughout Nigh below 90 cm ~d Moderate None

6 Uma, b None .~h~ne L~ throughout ~ Moderate Rapid Frequent

6 One. d, None None Low throughou~ 5o~ Good Rapid Rare 6 Dbc

5 Dbb None Subso&l ,'~ay be Moderate to high Nigh below 60 cm Moderate Moderate O~cas&onal exp~slve throughout

6 Dbd, e None Subsoil may be Low to ~oderate Low Go~d Moderate Rare expansive throughoul

6 Ufd None None Low throughou~ Lo~ Moderate Rapid but water Frequent ~ables may develop

5 Ucb None None Low ~hroughout Low Moderat~ Very rap~d but water Rer~ tables may develop

5 Gab None None ~ ~hroughou~ ~ Good Very rapid Rare

6 Gnc Sink Sub~oll below 90 cm Moderate below i0 cm High below 90 cm Moderate Hoder~te Rare hole~ may be expansive high below 60 cm

6 Dra, b, None None Low to ~oderate Low GOOd Rapid ~are 6 Dyc, d throuBhout

6 Drc, None None Low to moderate Low ,Moderate Moderate Rare 6 Dye, f throughout

6 Dye, b None None ~ow Low Moderate Rap~d Rare

6 DyR None Subsoil may be Moderate to high NIBh below JO cm PWr Moderate Rare expansive ~hroughout - 7 -

TABLE 1.4

!.~'.~a~d ~=r~ :~.;x~:~ =~ss~f~ca:~n :f Z:~ OCO ~'~pp'.ng un~ca

Happxn 8 unit Happed acea Coops ochec than rxce* R~ce* (hec~&re~) L£m~tat~on Land ¢~ L=mi~acion L~nd c~a~ sub-c~a~ ~ub-c~a~s

~...U~ ~ .A"/~ t3, ~Z, ~Z, =~ ~ =~, ~2 ~ ~ Ohm ~2 pb3, pc3, pd~, so~, tl ~ t~, pd3, pi 6 ~ 3bb 105 . pb2, pc3, pd~, so~, ti ~ t~, pd3, p~ ~ 2~ ~ tl, ~3, w3, ~3 ~ :3. ~3 f3, 02 3 2..Q*~f" ,.%'f~J'~ ~i, S3, w3. f3 ~ t3. g3 ~3, p2 3 ~ Oyc ~0 t~. g3. ~3, ~3 ~ :~. g3 f3. ~2 3 2.~I~.'6 ~0~ t~, g2, w2, ~Z 3 ~i. g2 ~Z Z 2 ~ ~ tl, g2, w2. f2 3 t~. g2 f2, p2 2 2~K '~rl~5 so2, tl, g3. f2 3 ~1, g3 ~3. p2 3 2 ~c- llg pd3, so2, ~2, gl 3 6, p2 5 2 Ugt 2 Dbc 365 pb2. pc3, soZ, Cl 3 tl. p3 3 2 Dbd 1 026 pb2, pc3, so3, tl 3 ~I, p3 3 Z Dbf &7 pb3, so2. tl. f2 3 tl. pl 1 2 Dyb 13 570 pb3, pc3. sa3, SO3, ~l, f2 3 ~ tk, pl l 2 Dda 688 pb4, pc], SO2, ~i, f~ 4 tl, pl i 2 Ddb [ 53~ p~, pc3. sa3, s~. tl, f2 5 ti, pl i Z~" 5 pd4, sa3. tl. g2. f3 ~ ~3, ~2. f2, p5 5 2 Ddd 261 pb3, pd4, s~, so2, ti, f] & tl, p5 5 4 Ucb 242 pt4, c4, a3 4 ~, p5 5 4 bee 83 dZ, pt3. t3. e3 4 ~5, p5 5 4 Dyd 153 pt3. t3. e3 4 :5. p5 5 4 Gnb ~ pt2. t3. ~3 3 tS. p5 5 4 Uc: I 319 pC4, C3, e3 4 iS, p5 5 4 Dy3 31 pd4. pt2. so2, t3. e3 4 iS, p5 5 4 O~a 354 ~d~, pc2, t3, e3 4 iS. p5 5 5 Dra 267 pcZ, ~3. r3. e3 3 t5. p5 5 5 Dye 117 ~b2, p¢2. ~o3. ~3. r3. ~3 & tS. p5 5 5 Dy~ 223 pc2. t3. ~3. ~3 3 iS. ~5 5 6 Uma 183 pc2, :Z 2 t5 p5 5 6 Gna 834 pc2, f2, ~2 2 c5 p5 5 b Gnd i 237 pt~, t2 2 t5 p5 5 6 Dbb 803 pb~, pcZ, ~oZ, tl, ~2 3 tl p6 4 6 Umb 1 229 pc2, t2. fZ 2 ~ p5 5 6 Dbc 2 3~ pc2. ~2 2 t5 p5 5 6 Dbd i 926 pb2, pc2, ~2 2 ~5 35 5 6 bbe 1 ~4 pb3, pc2. t2, f2 3 t5 p5 5 6 Ufd 13 p04, t3, f3 4 t5 p5 5 6 Ucd ~9 pd3, p~4. t2 4 ~ p5 5 6 Gnb iii pt2, c2 3 iS, p5 5 6 Gnc 356 p¢2, pd&, ~o2, ~i, f2 A El, ~5 5 S Dra 271 t2 Z iS, p5 5 6 Drb 964 pc2, t2 2 :5. p5 5 6 Drc 2 953 ~, De3, ;1. f2 3 ~3, ~ & 6 ~ya 517 ~c3, tl 3 tl. p5 5 6 Dyb 2 278 pt2, tl 2 tl, p5 5 6 Dye 63 pc2~ ~i 2 ~i, ~5 5 6 Dyd i 152 pc2. =i Z tl. p5 5 6 Dye 134 pd3, so2, ~i 3 tl, p5 5" 5 Dyf 8 470 pb2, pc3, tl, f2 3 tl, p4 & 6 Dyg 459 pb3, pd4, ~o3, =! 4 ~I. pl, pd4 G

* See Appandix 9 for de~azls of ¢laestfzca~los schemes.

*" ~e comb~na~%on of [tm%~a~ion sub-classes for this ~pp~n 8 un%t &nd~cate :ha£ i~ ~hould be ~nd Class &. H~ever, we be[lave tha~ observ~ :top perfomnces on LE justify %is consideration as Land Class 3. - 8 -

TABLE l.S

.~C:~ 'for chloride, $od¢c¢c~ :~ auc~aCs t~ ~he s~p~d so¢i ~fc~e c~cssss

Soil Chloride Sodtct~y Phosphorous ~x~rac~b ~e ~pper Zinc M~ng~nese To~a~ Organic Total profile pc~ass~um n~ro~en carbon sulphur clmss 0-1C cm 80-90 c~ 20-30 cm 80-90 cm Acid Bicarbonate

2 U8d v. i~ ~edi~ non-sodIc sodi¢ v. Low v. low ~di~ medl~ ~dlum hi8h Low low low 2 Dye v. low medi~ son-sodL¢ sodlc v. low v. low med%~ low medi~ high low low low 2 ~e v. low ~di~ non-s~Ic sodlc v. low v. low medi~ medium ~edlum ni%h iOW IOW IOW ~ Ugg v. IOW ~di~ non-s~ic sodic v. low v. low medium ~edl~ medi~ hish [~ low ~ow 2 L'gh v. low medium non-sodic stron~iy v. low v. low medi~ medi~ Low ~di~ low low low sodLc 2 Ugl v. low high non-sodlc s~ronsly v. [~ v. [~ medi~ ~di~ low med!~ low tow low sodlc 2 Ddc v. ~ow high sodlc s~rong~y v. low v. ~ow medi~ v. hi%h ~di~ hish ~ow Low ~ow s~Ic 2 Dbc v. low v. low -

2 Dbd v. ~o~ high s~ic strongly v. low ~di~ ~di~ ~di~ hi%h low low Io~ ~ow sodic 2 Dbe v. i~ i~ - . 2 Oyb v. Low h~h strongly scron~[~ v. low v. low low ~di~ m~ium high Low low low sod%c sodlc 2 Dda v. low h~gh ~ic strongly v. ~ow v. low ~edlum ~di~ [~ ~di~ low low !ow ~od~c 2 Ddb v. low high strongly s~on%ly v. IOW v. low ~di~ medi~ ~di~ hi%h low low low sodic sod~c Z USJ ~d~um v. ~£sh Z ~d v, io~ ~di~ i Ucb v. lo. v. ~ & Ucc v. L~ v. Low ~ Gnb v. Low v. ~ow non-sodic non-s~c v. Low v, !ow medt~ Lo~ m~i~ ~dl~ low Low low .- & Dga v. low v. low

S Dy~ v. low v. ~ow 6 ~mb v. low v. ~ow ~n-~Ic non-sodEc v. hIsh hxsh high mmdx~ m~d[~ hish low medium ~dl~ G Dbc v. i~ v. low non-sodic non-sodic v. high high ~di~ medi~ ~I~ ~edi~ low low low % Dbd v. low v. low non-sodlc non-coder v. high high medi~ ~di~ ~dl~ hish low low iow 6 Dbe v. low v. low non-s~Ic ,on-sodlc ~edlqm ~dl~ medz~ medi~ m~i~m high low low !ow 6 Gnb v. low v. ~ow non-sodlc non-aodlc v. low v. low low low ~i~ ~edi~ v. low i~ low 6 Gnc v. i~ low non-sodic sKron~iy v. iOW v. low low ~di~ low ~di~ v. Low low low ~:c

6 Dra v. low v. low non-sodIc non~sodic low !ow ~d~ ~dl~ ~di~ high v. low ~ow low 6 Drb v. I~ v. low non-sod~c non-sod~c v. low v. low medi~ ~d~ ~di~ h~h low low low 6 Dya v. low v. low son-sodic non-~ic ~di~ ~di~ ~di~ ~di~ ~di~ hIsh v. low i~ low 6 Oyb v. Iow 6 DTC v. ~ow v. i~ ~ Dyd v. [~ v. low non-sodlc non-sodic low low zedi~ ~dl~ ~lum h~h v. !~ low low 6 Drc v. low v. low son-sodlc sodic medi~ ~di~ m~l~ ~di~ medi~ high low . i~ low 6 ~e 9. low medi~ 6 Dyf v. low v. low non-sod~c ~on-sodic v. low v. low medi~ medi~ ~d~ hi&h i~ low low ~ Dyg v. IOW v. iOW s~ronsiy s~ronsiy v. low v. low ~i~ ~di~ m~i~ h~h v. low v. low v. !OW sodic sodlc

Hote: SOdtclI:y ratings 8~'cer No~'=hcote ~,nd $~ene (197~). -- Other ra~zngs based on Bruce and BaymenI: (1982). PART B

DETAILED REPORT

2. INTRODUCTION

2.1 Historical

At the conclusion of World War II, the underdeveloped areas of the Lower Burdekin Valley came under consideration for irrigation development via the soldier settlement scheme. Reconnaissance soil and land surveys of Skerman (1951), Hubble and Thompson (1953) and Christian ~ ~t~. (1953) were undertaken after an inspection by Stephens (1947). Reconnaissance soil and vegetation surveys covering all or part of the region have since been undertaken by Isbell and Murtha (1970), van Wijk (1971) and Isbell and Murtha (1972). Map scales ranged from 1:190 000 to i:i 000 000.

When irrigation of left bank levee areas at Clare, Millaroo and Dalbeg was approved, detailed soil surveys with map scales of i:7 920 were undertaken by Agricultural Chemistry Branch Staff (unpublished data) for farm design purposes. These surveys cover only the levee and adjacent flood plain areas.

As part of the re-evaluation of the development potential of the Burdekin Basin reported by the Burdekin Project Committee (1977), a semi-detailed reconnaissance soil survey off the right bank area from Mr. Louisa to the Elliot River was carried out by Thompson (1977). The map scale of this survey was 1:100 000 with four selected reference areas mapped at 1:25 000.

• 2.2 .Purpose and Extent of Survey

The soils map of Hubble and Thompson (1953) covered only the southern portion off the area commandable for irrigation on the left bank. Because of the small scale of all published soil maps, existing information on the Burdekin left bank was considered to provide inadequate detail to allow a reliable assessment of the area for irrigation. This survey was undertaken at a scale appropriate for irrigated land use assessment. The aims were to provide more detailed information on properties, distribution and irrigation suitability of soils and to assess areas of various soil classes and the degree of soil variability. It also provides information at the same scale and in a similar format to that published for the right bank by Thompson (1977).

This report covers an area of approximately 80 000 hectares on the left bank of the Burdekin River below Gladys Lagoon and extending north-west to the Haughton River. It is generally confined to the river levees, prior streams and their associated levees and flood plains of the Burdekin and Haughton Rivers but excludes the present Burdekin Delta area. It lies entirely within the area given as commandable for irrigation by the Bu~dekin River ~uthority (1951) but extends west of the irrigable area proposed by the Burdekin Project Assessment Committee (1978). - 10 -

SCALE 10 0 10 20 30 40 50 km

,~ t ~'~

, ...... )

FIGURE 2.1 LOCALITY PLAN

3. SOIL SURVEY METHOD

3.1 General

The technique use6 was based on the reference area concept. It appeared from Hubble and Thompson (1953) and. Isbell and Murtha (1970) that the Burdekin Rural Education Centre, occupying 3 ?44 hectares, was representative of a substantial propomtion of the survey area. As detailed soil survey information was also required for planning the development of this Centre, it was mapped first as a reference area.

Within the reference area, controlled traverses were run and 320 si%es were selected fo~ profile description on photopattern, vegetation and topographic position. Soils were augered to 150 cm, described and classified accordin~ to the Factual Key of Northcote (1979). Profile characteristics riot included in this classification were also recorded and used as necessary when formulating soil classes. Soil structural descriptions were made on limited numbers of 15 cm-diameter Proline cores or 5 cm-diameter thin walled tube cores. The profile descriptions obtained were grouped into 28 soil profile classes (see glossary) which were used as a reference to map the reference area at 1:25 000 on I:I0 000 colour air photographs. Mapping was by free survey and a further 1 000 recorded ground obseryations of sufficient detail to identify soil profile classes were made. -

A further 320 detailed profile descriptions were made on controlled traverses throughout the remainder of the 80 000 hectare area. Computer cards for these descriptions are held by Agricultural Chemistry Branch, Meiers Road, Indooroopilly. Computer and hand sorting techniques were used to group these into existing and 14 new s0il profile classes and seven miscellaneous mapping units (hills, swamps, etc.). Using these soil profile classes and mapping units, eight soil profile classes defined by Thompson (1977) on the right bank and three defined by W.P. Thompson • (unpublished data) south of this survey area, I:I00 000 mapping was undertaken by air photo-interpretation with extensive field checking. Checking observations, sufficient to identify soil profile classes, totalled 1 400. - ii -

Soil boundaries within the Clare irrigation 8mea were taken from the maps of Agricultural Chemistry Branch Staff (unpublished data) with limited ground checking to confirm mapping units.

. 3.2 Soil Profile Class and Mapping Unit Derivations

3.2. I Soil ~rofi~ class

The basic soil grouping used is the soil profile class. Soil profile classes were obtained by grouping profiles of similar morphology, so the system is an ascending one commencing from observed soil morphology. Vamiation in characteristic soil morphological properties is less within classes than between classes. In grouping soil profiles into soil profile classes, emphasis has been given to those characteristics considered likely to have greatest significance for irrigated land use.

On the basis .of apparent origin of parent material and position in the landscape, all soil profile classes have been given a symbol (1, 2, 4, 5 or 6; Thompson 1977) to indicate their topographic form (see glossary). Each soil profile class is thus designated by an alpha numeric code: a number for the topographic form, the appropriate symbols for a subdivision within a primary profile form (Northcote 1979), and a letter for each separate soil profile class within that topographic form and primary profile form subdivision. For example, in unit 6 Dya, "6" denotes topographic form 6 (miscellaneous alluvial deposits), "Dy" indicates the overall profile morphology and represents the dominant primary profile form subdivision (Northcote 1979) and "a" denotes a separate soil profile class distinguished on characteristics other than those s~mmarised in the primary profile form subdivision notation (eg: depth and texture of surface horizon and reaction trend). The letters used take account of those already used by Thompson (1977) and W.P. Thompson (unpublished data).

3.2.2 Mapping un~

Two types of mapping units are used. At 1:25 000, the reference area has mostly simple mapping units with one soil profile class occupying greater than 70~ of each mapping unit area. These mapping units are identified by the code for the dominant soil profile class. Where one soil profile class occupies less than 70~ of ~he mapping unit, the compound mapping units formed are identified by the codes for the two most common soil profile classes.

At I:I00 000 scale, most mapping units are compound, but are generalIy identified by the codes for the most common soil profile cIass. However, a mapping unit predominantly occupied by two soil profile classes that only occur as a complex, (eg: 2 Ddc - 2 Ugi) is identified by the codes for both.

4. PHYSICAL ENVIRONMENT

4.1 Climate

4.1.1 G~

Available climatic data for the region have been reviewed by Christian @St ~. (1953), Australian Bureau of Meteorology (1970) and Burdekin Project Committee (1977). Table 4.1 summarises data likely to be important agronomically.

The a~ea is almost frost free with warm sub-humid conditions and a marked seasonal rainfall pattern. The rainfall probability data in Table 4.1 indicate that variability is high.

4. I. 2 Rainfall distribution

Rainfall distribution shows a distinct four month Wet season from December to March when, on average, 70% of the annual rainfall is - 12 -

received. The time of commencement of the wet season is highly variable. Intense storm rains may be received in November or December interrupting land preparation and cane or rice harvesting.

4.2 Geology and Geomorphology

4.2. I G~n~/

The left bank survey area falls within that covered by the geology reports and maps of Christian ~t ~. (1953), Gregory (1969) and Paine (1972). It consists of an alluvial plain surrounding four small outcrops of bedrock.

The geomorphology of part of the area and its surrounds has been commented on by Hubble and Thompson (1953) who suggest that deposition of the alluvia occurred in the late Pleistocene and early Holocene periods. Hopley (1970) has described the geomorphology of most of the area in some detail. He identified a number of abandoned river channels and suggested a relative chronology for some of them.

The survey area abuts saline marine flats to the north. These are generally from 2 to 7 m below the flood plain and levee systems and, as one proceeds north, appear to grade from those no longer inundated by sea water through those occasionally inundated. About a kilometre north of the Barratta rail siding is a sandy ridge that, from the coarse size and poor sorting of the sand, appears to be an alluvial deposit.

Alluvial deposits apparently laid down by local creeks and their prior streams occur to the south and south west of the area. Nine Mile Lagoon and 0aky Creek may have been important in the deposition of much of this area which is generally i to 2 m above the flood plain.

4.2.2 Geology

The bedrock outcrops are Upper Carboniferous in age and form part of the Connors Arch structural framework (Paine 1972). They rise from 5 to 160 m above the alluvial plain with slopes of 2 to 5% except wher~ steep rocky outcrops occur. Ridges with sedentary soils developed on granodiorite occur north-east of Gladys Lagoon and north of the junction of 0aky and Barratta Creeks. The only geology map showing the latter ridges is that of Christian ~ ~. (1953). At Kelly Mountain, granite outcrops occur surrounded by concave pediments overlain by sandy material. The overlying materials have been described as outwash fans by Hopley (1970) but because of their complex and coalescing nature they are here referred to as outwash plains.

4.2.3 Fluvial geomorphology

General

The alluvial deposits of the area include the levees and flood plains Of the Burdekin "and Haughton Rivers and their numerous abandoned channels of widely varying ages. The morphology of abandoned channels varies from those with well defined levees and beds to those with narrow beds (6 Ucb or 6 ~ya) and occasionally narrow levees (usually 6 Dyf). Others may have narrow levees of topographic form 6 soils alongside a depression of topographic form 2 cracking clays. Others occur as flood plain soils underlain by coarse material (2 Ugj or 2 Ddd) and carry vegetation atypical of the flood plain. In some cases, levee or possible alluvial fan deposits can be identified where surface evidence of an abandoned channel is absent. - 13 -

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o o I I I I I 1* "~ • , ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 0 1 ~ ~ .~ .~ ~ ~ ~" ~ ~ $ ~ ~.~ $ ~ g=* ~ ~= 888 ~ ~ 8~ ~ ~ ~~ ~ : ~ ~ ~ ~ ~ ~ ~ ~ ~ X ~ X 7 ~ ~ ~ ~ ~ ~ £ ~ ~ ~ * ~ ~ ~ o o o ~ ~ • ~ o o ~ o ~ ~ ~ ~ ~ ~ ~ ~ "~ 1 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~.~~ ~ ~ ~ ~~ ~ ~ ~ ~ ~ ~ ~ % ~ ~ ~

~ ~ ~~ ~~ ~ ~ N ~0 ~ ~ ~~ ~ ~~. ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~e ~ ~ ~ ~ ~ ~ ~ ~ ~O ~O ~ ~ ~ ~ ~ ~ ~ }gg~~ g ~ g ~ ~ ~ ~ ~ ~ ~ooo ~ ~ ~ : ~ ~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ "~ ~ - 14 -

Hopley (1970) suggests that two separate old deltas occur in the north of the survey area. One lies east of the HaughtOn River near Giru and the extensive areas of topographic form 6 soils (6 Dyf, 6 Drc) mapped here in this survey may represent part of this. Its extent may indicate that it was either a Burdekin or Burdekin plus Haughton delta. A buried meander scroll has been identified in a 2 Ugd mapping unit in the north east of this area (R.H. Gunn, personal communication).

The second delta lies in the present Barrattas area east and north of Barratta rail siding. Hopley (1970) infers that this is the younger, being the Burdekin delta prior to its diversion through The Rocks. He states that this has been buried in parts by apparent marine deposits laid down at the height of the Holocene transgression. This survey found that the swamps mapped between the Bruce Highway and the main northern rail- way in the Barrattas area are frequently underlain by cat clay so it appears that parts of this old delta have been further buried by shallow alluvial deposits. In the west, these probably came from an abandoned Haughton River channel and Barratta Creek but in the east they apparently c~me from the Sheepstation Creek-Burdekin distributory system.

The alluvial deposits also include at least the lower parts of the local alluvial-colluvial plains adjacent to the granodiorite outcrop north-east of Gladys Lagoon and the outwash plains surrounding Kelly Mountain. This survey produced no direct evidence to indicate whether or not the lower parts of these outwash plains encroach on the adjacent flood plain. The presence of water tables in the deep sand profiles at some sites immediately adjacent to the flood plain suggests that flood plain clays with low permeability underly the extremities of the outwash plains.

Burdekin River

Major abandoned Burdekin River channels and levees have been identified by Hopley (1970) in five areas. These are:

west of Sheepstation Creek just east of the survey area.

immediately west of Kelly Mountain.

to the north of Clare.

north-west of Clare through the Burdekin Rural Education Centre.

at Gladys Lagoon.

The latter channel lies along a fault line as shown by Paine (1972).

The channel through the Burdekin Rural Education Centre is the best preserved of the above. Its course, as identified in this survey, has been partly obliterated by the incision of Barratta Creek, but it is again identifiable where it was deflected east by the bedrock outcrop in the centre of the survey a~ea. Some ten kilometres further north towards the coast, this channel is buried by younger flood plain deposits. Hopley (1970) suggests that it was the course of the Burdekin immediately prior to the diversion through The Rocks and that it was joined by an abandoned Haughton River channel above its now buried delta in the Barrattas area. Its upstream end has been filled for over two kilometres by the present Burdekin levee and it serves now only as a collector of overbank flow and local run off.

Some of the abandoned Burdekin channels mapped by Hopley (1970) were not identified in this survey. In these cases, the only evidence of an abandoned channel on the surface and in the upper 150 cm is the stream li~e form of depressions in the flood plain. - 15 -

The course off the Burdekin within the survey area has apparently been unchanged since its diversion through The Rocks.

Hau~hton River

Hopley (1970) mapped two abandoned "Haughton River channel systems to the west of the survey area and one within it. The latter leaves the present channel at about Australian Map Grid Reference (AMG) Zone 55K: 508000 E, 7821000 N and flows to the west of, then along Baratta Creek. Its upstream end has not been completely filled by the present channel levee so it serves as a distributary channel before the river breaks its banks in other localities. The levees of the main abandoned channel are readily identifiable throughout its course to the swamps north of the Bruce Highway. This survey found no evidence that this channel joined the lower part of the abandoned Burdekin River channel through the Burdekin Rur,al Education Centre as was suggested by Hopley (1970). However, the bedrock contours shown by Hopley (1970) suggest that the Haughton has been a tributary of the Burdekin at some stages during the late Pleistocene and early Holocene.

Abandoned channel systems apparently associated with the Haughton River but not mapped by Hopley (1970) were identified at AMG Zone 55K: 512000 E, ?834000 N and 515000 E, 7830000 N. These contain examples of both prior stream and channel infill form and appear to have been distri- butaries of the Haughton. As they generally show little levee development and relate poorly to the soil mapping units, they may have been incised into an existing land sugface.

To the west of Hopley's (1970) map, an abandoned channel system apparently leaves the present Haughton River near AMG Zone 55K: 500000 E, 7815000 N. This leads to a fan-like alluvial deposit at AMG Zone 55K: 507000 E, 7818500 N and may be associated with the complex abandoned channel system centred at AMG Zone 55K: 509500 E, 7817000 N. The latter may alternatively represent prior channels of Oaky Creek but topographic form 6 soils are not generally associated with its present course within the survey area.

Present Drainase Lines

Many of the broad drainage lines throughout the area show evidence of active erosion. Gully tributaries of Oaky and Barratta Creeks are extending along them and gullies from the saline marine flats are lengthening. This may indicate that climatic change has accelerated erosion since the deposits were laid down or that the deposits are relict in nature, being laid down when sea level (base level) was higher than at present.

Two lagoons occur in Woodhouse Creek just to the north of Woodhouse Homestead. These are not associated with any abandoned channel and have apparently been eroded immediately below the decrease in gradient where the creek flows from the pediments and outwash plains onto the flood plain. Woodhouse and Barratta Creeks are depositing a sandy alluvial fan just north of these lagoons.

Relevant Chronology

The postulated chronology of the development of the alluvial ~andscape within the survey area is summarised in Table 4.2 and discussed in detail below.

Hopley (1970) suggests that the three most recent abandoned Burdekin channel systems in the Clare area are, in order of decreasing antiquity, the Gladys Lagoon system, the system to the north of Clare and the system through the Burdekin Rural Education Centre. He suggests that the latter was abandoned prior to the maximum Holocene sea level transgression. This chronology appears correct.

- 17 -

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4-~ 0 ~ ~ ~ ~ ~ ~ ~ ~ ~ 0 0 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~o ~o ~o ~ ~o

o - 18 -

We suggest that the large area of topographic form 6 soils east of the Haughton River south west of Giru represents part of an old delta and Hopley (1970) infers that it is older than a buried delta formed prior to the maximum Holocene sea level transgression further east. From its elevation, it was apparently deposited when sea level was approximately as at present. Though Hopley (1970) conjectures that an interstadial high sea level may have occurred more recently, it appears that the last time prior to the Holocene when sea levels were at or above the present was the late Pleistocene interglacial (Bloom ~ ~. 1974) so these deposits may be of this age. To have remained intact since the material was deposited, this area must have been removed from the zone of incision of the Burdekin and Haughton rivers during the last glacial maximum about 15 000 years ago. Hopley's (1970) map of late Pleistocene surface contours indicates that this zone was in the Barrattas region further east. . The suggested late Pleistocene delta is dominated by soil profile classes 6 Dyf and 6 Drc as is the levee of the abandoned channel at Gladys Lagoon and the Haughton levee above AMG Zone 55K: 500000 E, 7815000 N. This affinity may indicate that these deposits are of similar age. The latter deposits are well above the level of recent record floods (A. Arana, personal communication).

The late Pleistocene interglacial high sea level and the time of maximum Holocene transgression should provide two absolute time points in the relative chronology. It seems generally accepted (Bloom ~t ~. 1974, Hopley and Murtha 1975, Wyrwoll 1977) that the late Pleistocene interglacial sea ~evel was about 6 m above present and was about 125 000 years before present. If the deposits east of the Haughton River represent a late Pleistocene delta, they are therefore of this approximate age.

The time and extent of the maximum Holocene sea level transgression is more open to debate. It is given as three to four metres above present between 5 000 and 4 000 years before present by Hopley (1970). Hopley and Murtha (1975) and Wyrwoll (1977) give it as three metres above present 6 000 years before present, while Clarke ~ ~. (1979) suggest that it was at or very slightly above present 7 000 to 6 000 years before present. When the above are considered together with the rising sea level trend lines of Thom and Chappell (1975), we tentatively conclude that the Burdekin was diverted through The Rocks between 7 000 and 4 500 years before present. This therefore indicates the minimum age of the abandoned Burdekin channel through the Burdekin Rural Education Centre.

4.2.4 Classification and ~escription of ~opograp~ic forms

Thompson (1977) divided the relief characteristics of the Burdekin right bank into six topographic forms on the basis of geomorph- ological type and influence. Five of these topographic forms occur within this survey amea but to suit the different conditions of the left bank, some definitions have been altered slightly.

Local Alluvial-Colluvial Plains (Topographic Form i): Soils: ~ Ug~; I Dba, b.

These are plains of low relief, probably of Pleistocene age. The deposits are most likely associated with the weathering and erosion of nearby hills.

Grit is evident in all soils to varying degrees while low amounts of coarse gravel and stone occur in the soils of more elevated colluvial situations.

In slightly elevated areas, solodic-solodized solonetz soils are dominant (i Dba, b) while in areas of greater relief (i to 3% slope), linearly gilgaied grey-brown clays (1 Uge) are dominant. - 19 -

Major River Flood Plains (Topographic Form 2): So~Is: 2 Ugd, ~,f,g,h,i,j; 2 Dbc, d,~,f,; 2 Dyb, c; 2 Dda, b,c,d.

These plains of low relief ar~ associated with flood plain deposits of the Burdekin and Haughton Rivers. They occupy large areas and are dissected by prior streams and channel infills. These abandoned channels do not occur on the smaller flood plain area of the right bank mapped by Thompson (1977).

These flood plain deposits are generally fine textured and, because of the range in ages of the numerous abandoned river channels, they are probably of varying ages too.

The lower end of the abandoned Burdekin channel through the Burdekin Rural Education Centre has been buried by flood plain material, so a considerable proportion of the flood plain has been deposited since the Burdekinwas diverted through The Rocks. If the diversion-occurred early in the period, proposed in Section 4.2.3, the wetter-than-present climate suggested for northern Australia in the middle ~olocene by Clarke ~t ~. (1979) combined with probable high sea levels may have caused extensive flood plain deposition giving a mid Holocene age to some of the land surface.

The depositional history of the area is complex so it is impossible to accurately differentiate deposits of the Burdekin from those of the Haughton. However, subangular to rounded grit is almost absent from flood plain soils adjacent to the Burdekin or apparent abandoned channels of it while trace to small amounts frequently occur in flood plain soils associated with the Haughton or its apparent abandoned channels.

Bleached grey clays (2 Ugd) are dominant in low lying areas with minimal slope (< 0.02%) but grey clays (2 Ugf) and gilgaied solodic- solodized solonetz (2 Dyc) also occur. Depressions and drainage lines with higher slopes (0.02 - 0.5%) are also dominated by grey clays (2 Uge, g) though less frequently bleached. Grey clays of heavy clay surface texture (2 Ugh) occupy slightly elevated (i - 2 m) almost treeless plains. Slightly elevated areas and some levee backslopes, both of which carry open woodlands or low open woodlands of cabbage gum, are dominated by solodic-solodized solonetz soils (2 Dbc, d,e,f, 2 Dyb, c, 2 Dda, b). Limited areas with slopes > 1% are occupied by a linearly gilgaied complex with a solodic-solodized solonetz (2 Ddc) in the depressions and a grey clay (2 Ugi) on the mounds. Solodic-solodized solonetz soils (2 Ddd) and dark clays (2 Ugj) occur where shallow flood plain deposition has occurred over contrasting material such as sand or cat clay.

The slightly elevated clay plains of soil profile class 2 Ugh generally appear associated with the Gladys Lagoon abandoned channel system which is recognized by Hopley (1970) as the oldest readily identifiable in the area. They may therefore be older than much of the remaining flood plain area and could be of late Pleistocene age.

Dissected Uplands and Outwash Plains Developed from Acid Intrusives (Topographic Form 4): Soil: 4 Ucb, c,~; 4 Gnb; 4 Dyd, j; 4 Dga.

These ahre undulating granitic uplands grading into outwash plains. Except for areas of rock outcrops, slopes are generally 2 to 5%. Upper slope positions are usually dominated by red podzolic soils (4 Gnb) or sands with a pale A2 horizon (4 Ucb). Some acid and neutral yellow duplex soils (4 Dyd) and bleached sands over a silcrete pan (4 Uce) also occur. The lower slopes are characterised by bleached sands (4 Ucc) with gleyed duplex soils (4 Dga) and occasionally solodic-solodized solonetz soils (4 Dyj) along major drainage lines.

This topographic form only occurs in the Kelly Mountain portion of the survey area.

- 21 -

The surface gravel deposit at AMG Zone 55K: 514300 E, 7812200 N apparently represents an inlier, being part of the bed of an abandoned channel from the slightly elevated country to the west surrounded by flood plain material.

The swamps are too wet for cultivation for more than six months in most years. Those north of the Bruce Highway are generally occupied by soil profile classes 2 Ugj and 2 Ddd (over cat clay) while the rest are occupied by 2 Ugd and 2 Ugf. South of the Highway, the swamps include areas behind man made banks (eg: AMG zone 55K: 515000 E, 7834000 N), areas receiving irrigation run off water (eg: AMG Zone 55K: 518000 E, 7813000 N), areas surrounded by abandoned stream channel levees (eg: AMG Zone 55K: 512000 E, 7823300 N) and areas that may be very old abandoned channels with the lower ends blocked by more recent deposition (eg: AMG Zone 55K; 521000 E, 7832100 N; 529200 E, 7830000 N).

4.3 Hydrology 4.3.1 Surface hydrology

While part of the right bank area surveyed by Thompson (1977) is drained by minor tributaries of the Burdekin, none of this left bank survey area is drained by either the Burdekin or the Haughton. The well developed levees of these streams prevent them providing local drainage. Barratta Creek and its major tributaries, rise to the south and south-west of the area. Collinsons Lagoon, Horseshoe Lagoon and several minor creeks eroded 1 to 2 km back into the flood plain from the saline marine flats provide the only other drainage.

The dissected upland areas of topographic forms 4 and 5 within the survey area are drained by gullies and broad drainage lines that end, often in alluvial fans, when they reach the flat areas of the flood plain. The miscellaneous alluvial and flood plain areas of topographic forms 6 and 2 are drained by very broad based drainage lines that are being incised by minor tributaries of the Barratta Creek system or the small creeks to the north of the area. Because the present drainag¢ system over most of the a~a is so poorly developed, an ~x~en~ive drainage n~twork to r~mo~ irrigalion run off wal~r will b~ an ~ssent~ p~ of any f~r~h~r irrigation development.

Much of the area is subject to inundation from local run off by overbank flooding from the Barratta Creek system and from the Burdekin and Haughton Rivers. The broad drainage lines are probably inundated almost annually by local run off. From discussions with local landholders and Queensland Water Resources Commission personnel, it appears that the frequency of significant flooding in the Barratta Creek system is every 3 to 5 years and for the Haughton River, every 5 to 7 years. The Burdekin Project committee (1977) estimates that the Burdekin breaks its bank within the survey area when the discharge at Clare reaches 29 000 cumecs and it appears that the recurrence interval of this flow is 12 years. The record Burdekin floods of 1958 and 1946, when discharge at Clare reached over 36 000 cumecs, have a recurrence interval of 23 to29 years (Burdekin Project Committee 1977).

Significant flooding occurred in the area in February 1978 when the Barratta Creek system flooded and the Haughton River broke its banks at numerous points below Piccaninny Station homestead. "Figure 4.1 shows the approximate extent of flooding estimated from maximum height recor- ders (Queensland Water Resources Commission, unpublished data) and flood debris, the depth of flooding in the area indicated was generally 20 to 150 cm. Though extensive, this flood caused negligible erosion and little damage to fences so flow rates were probably slow (see Plate B).

- 23 -

~ ~_~_C.,~=<~~ ~-. G~RU~ ~ ~T ~'Ly.

~ / // / , /"

(" )//~-",/~" /~" X "~'" KaLLY I X ~ , ~ MT ~" y/#~I ~\\

MT x :~ I~ower i;~e$ ,';O00~OUSE ~ ~ ~oundary of Survey A,'ea

Giacys I~ ~ F~oodea area l L~goo~ i ~ Scale h \k/~ km 5 0 5 10 15 \\\ I I , t I

BURDEKIN BASIN NORTHERN LEFT BANK SURVEY AREA

FIGURE 4.1 APPROXIMATE AREA FLOODED TO GREATER THAN 15cm IN FEBRUARY 1978, =~ = - 24 -

Miscellaneous Alluvial and Flood Plain Areas:

The available data show that most of the area is underlain by aquifers with varying quality waters. Generally, the most saline waters are those from bores adjacent to the saline marine flats towards the coast.

Thompson (1977) found saline ground waters in prior streams and channel infills. Bores for stock water have been sunk in similar situations near Horseshoe Lagoon in this survey area but no data are available on quality as the area is not grazed now and the bores are abandoned.

The Burdekin Project Committee (1977) identify three aquifer systems within the survey area. These are Mona Park, Barrattas and Haughton systems. The first two appear to be interconnected and are recharged slowly from the Burdekin River. The last is a small aquifer and is very dependent on flow in the Haughton River for recharge. Salt water intrusion along the edges of saline marine flats is a potentially severe problem should overuse of the Barrattas aquifer occur.

_ . B~cau~ a number of miscet~ous al~vi~ ar%a~ ~v~ a~~ p~bl~ ~~ in th~ lo~ p~ of ~he so~ pro~, s£epag£ loss~ from op~ ~h ~g~on c~nn~ ~y b£ ~gh. The oc~£nc~ o6 so~c so~ ~h mod~% l£v~ o6 s~y (2 Ddb, 2 D~) in som~ l~v~ bac~lop~ pos~o~ ~ ~ possibly l~ grou~ ~ mov~. from th£ ~gh~ lzv%£ ~ ~ ~£d s~~on in l~ ~nd- •. s~p£ ~os~on. ~~on ~ oc~ ~ong l£ve£ bac~lo~ ~d~ ..~ ~g~on.

Upland Areas:

The D~oblem of lateral watec movement f~om the sloDes of upland aceas on intermediate int~usives has been dealt with by Thompson (197~) who suggests that surface dcaina~e at the foot of slopes will be ne~essac~. Because of the small acezs of these uplands in this sucvey acea, the magnitude of the ~coblem is small.

The D~esence of veFy deed conspicuousl~ bleached soil hocizons, seepage areas and watec tables in downslope positions indicate that latecal ~ound watec movement also occucs in uDland areas on acid int~usives. This ~ound water movement may limit development of some downsloDe aceas and may ~equi~e sucfzce drainage of the foot slopes.

4.4 Natural Vegetation

Vegetation has been systematically recorded on all soil profile classes and Table 5.1 gives the most common structural form and species composition for each. Vegetative pattern has some correlation with topographic form and soil profile class pattern but considerable variation in structural form (Specht 1970) and species dominance can occur on a single soil profile class.

The most common structural form is low open woodland. It occurs on most soil profile classes of topographic forms i, 2 and 5, on duplex soil profile classes of topographic form 4 and on most solodic-solodized solonetz soi~ profile classes of topographic form 6 (see Plates C and D). Woodlands or open woodlands usually occur on other soil profile classes of topographic forms 4 and 6 while clay plains of 2 Ugh soil profile class generally support grasslands (see Plates D and E). It appears that the seasonal nature of rainfall allows denser or taller communities to develop only where profile moisture characteristics are favourable or where water tables last into the dry season.

- 27 -

5. SOILS - CLASSIFICATION AND MORPHOLOGY

5.1 General

A total of 53 soil profile classes were found to occur within the left bank survey area. These represent a wide range of great soil groups.

Table I.i gives major distinguishing features of soil profile classes and the relationships between topographic forms and soil profile classes.

• Appendix 2 lists the soil series of Hubble and Thompson (1953) that are approximately equivalent to soiI profile classes.

5.2 Morphology

Table 5.1 gives detailed descriptions of soil profile class morphology and the range of profile variation within classes. Conventions used in this table are given in Appendix 3.

5.3 Mapping Units

Derivation of the mapping units used is discussed in section 3.2. The mapping units for the i:i00 000 area and their composition are listed in Table 5.2 while Appendix 4 lists similar information for the 1:25 000 sample area mapping units.

In Table 5.2, the soil profile classes listed in the dominant and associate soil profile classes columns occupy 70% of the mapped area. Though all photo-patterns were field checked, air photo interpretation was relied on extensively so it is impossible to accurately predict percentage composition for the I:i00 000 mapping units. In general, the major soil profile class occupies greater than 50% of the mapping unit area. The associate soil profile class composition can vary from area to area (eg: mapping unit 6 Gnc consists predominantly of 6 Gnc and 2 Dyb in the Clare area but is predominantly 6 Gnc and 2 Ddb. where it occurs between Oaky Creek and the Haughton River).

5.4 Soil Variability in i:I00 000 Mapping Units

A comparison of the 1:25 000 reference area map with the i:i00 000 map allows a visual estimate of the variability in the i:i00 000 mapping units to be obtained. The reference area map shows how the detail of the soil profile class distribution within the landscape is amalgamated to give the I:I00 000 soil profile class association mapping units.

The role of the dominant, associate and particularly the minor soil profile classes in determining soil variability at a farm design level within the i:i00 000 mapping units (Table 5.2) can be seen from the reference area map. Appendix 4 shows that even at 1:25 000, variability is such that th~ mapping units consist of:

(a) Simple mapping units where minor soil profile classes may contribute up to 30% of the unit (eg: 6 Dra).

(b) Compound mapping units (associations of soil profile class) where the dominant soil profile class occupies < ?0% oE the mapping unit but where the area occupied by it and an associate soil profile class exceeds 70% (eg: 2 Uge - 2 Ugd).

All soil profile classes do not occur as mapping units in the reference area but the reference area map and Appendix 4 can be u~ed to estimate the variability that is likely in many of the I:I00 000mapping units. While the soil profile classes may not be the same, soil distribution in the various landscape positions within topographic forms 2 and 6 is generally similar to that within the reference area. 28a

28b

29a

29b

30a

30b

31a

31b

32a

32b

33a

33b

34a

34b

35a

35b

36a

36b

37a

37b

38a

38b

39a

Soil Profile P.P.F Soil Profile Description Topographic Dominant Class Form Vegetation 6Dbc Db 2.32 Greybrown podsolic Db 1.32 soilsHardsetting surface Db 1.22 Db 2.22 Miscellaneous Woodland to Db 2.32 Alluvial low woodland Deposits with A1: Dark to Brown 7.5yr,10yr 2/2, 3/1, 3/2, 3/3 fine poplargum sandy loam to light sandy clay loam to sandy fine sandy and grey clay loam to fine sandy clay loam to loam fine sandy. – hardwood Massive to weak medium subangular blocky, dry soft toslightly hard. Recent with canbeen Haughton and cockatoo A2: As above but brown to yellow brown 7.5yr, 10yr Alluvial apple 4/3, 4/4, 5/3 and frequently sporadically bleached Deposits associated

B21t: 7.5yr, 10yr 4/4, 4/5 light medium clay to medium 0-1% slope Strongly clay, strong medium blocky frequently with argillans developed dry hard to very hard. Occasional manganifeous veins grass layer of Rarely found in spear grass, B22t: As above but light clay to light medium clay and orgillans always present alluvial for Giant spear areas to south grass, brown D1: Brown to yellow brown 7.5yr, 10yr 3/3, ¾, 4/4, 4/6, sorghum and 5/4, sandy loam to sandy clay loam sandy, weak coarse kangaroo subangular blocky, dry slightly hard, occasional grass. manganifeous concretions

D2: (Occasionally present) Brown to grey 7.5yr, 10yr 3/3, 4/2, 4/3 light clay to light medium clay, strong medium blocky, dry hard manganiferous concretions and veins

Variants A yellow brown 7.5yr, 10yr 5/4, 5/6 B21 horizons occasionally occur

D Horizons of medium clay of Topographic form 2 origin may occur below 90cm (Db 2.32)

6Dya Dy 3.41 Yellow podsolic soils: Dy 3.42 Hardsetting surface Dy 3.85 Dy 3.32 Miscellaneous Woodland of Alluvial poplar gum Deposits of and grey A1: Dark to brown to grey (7.5yr, 10yr 3/1, 3/2, 4/1, major creeks bloodwood 4/2, 4/3) Loamy sand to sandy loam massive to weak and rivers with carbon coarse subangular blocky dry, slightly hard. and cockatoo Levees and apple A2: Frequently moderately yellow mottled grey alluvial fans to yellow brown 7.5yr, 10yr 5/3, 5/4, 6/2, 6/3. Loamy Strongly sand equivalent to sandy loam, massive, dry soft developed manganiferous concretions and veins. grass layer of spear grass Variant: D horizon of yellow 10yr, 2.5yr, 7/4 to 7/6 or and giant gritty clayer sand may occur below 130cm. speer grass

39b

40a

40b

41a

41b

- 42 -

.. TABLK 5.2 Z:IOO SO0 ~PP~9 un%= co~Os~C~On

Mapp~n s unit and Associate Minor Area dominant $o~I profile so~l profile classes soLl prof~ie classes (hectares) class

i USe i Dba, I Dbb ;l i Dba 5 Dyc I Dbb a2 i Dbb I Dba 5 Dra !05 2 U~d 2 Uge, 2 Dye Z USS, 2 U%f, 2 Dyo, 6 Dyf !l 030 2 USf 2 USd , 2 U~ Z Dye 399 2 Dyc 2 Ugd 2 U~e, 2 Dyb, 6 Pyf &10 2 USe 2 Usd, 2 Dyb 2 Ug s 2 Ddb !0 ~09 2 USg Z UGh , Z Use 2 USf Z Dyb 2 3&O 2 U~h 2 UK8 2 USe, 2 Dyb, 2 Ddh I 915 2 D~c - ~ US~ 2 Dyb Z Ush, 2 Ddb 17& 2 Dbc 2 Dbd, Z Dyb Z Pbe Z U~e, 6 Dyf 365 ~ Dhd 2 Dyb 2 Dbe 2 Dbc, 2 US~ , 2 Dyf i 026 2 Dbf 2 Dyb, 2 ~b 2 Dda 6 Dyf ~7 2 9yb 2 U~e, 2 Ddb 2 Dda 2 U~h, 6 Dyf 13 570 2 Dda 2 ~b 2 Dy5 2 U~e 6~8 2 Ddb Z Dda, 2Dyb 2 USa, 2 Ush , Z ~f, 6 Dyf ! 532 2 U~j Z Ddd 2 u~ 5 2 Ddd 2 U~J 2 Dy5 261 A Ucb 4 Gnb 4 UCc. & Uce, A D~a 2&2 4 Uce 4 U¢C & PSa 83 & Dy~ 4 Uc¢ ~ Uc~ 153 . ~ ~b & Ucb & ~a &~ ~ Ucc ~ DS~ 4 Uce, & Dyd i 319 4 Dy~ 4 Dga 4 Ucc 31 4 Dsa 4 Ucc 4 Dyj, 4 Uca 354 5 Dra 5 Dye 267 5 Dye 5 Dra 2 U~e i17 5 Dye 5 Dra 223 6 L~ 6 Gna 6 Dbb 183 6 C~ 6 U~ 6 Dy 8 834 6 ~d 6 Oyb, 6 Dy8 i ~37 6 Dbb 6 Gna 6 U~, 2 DyD 803 6 ~b ~ Db¢ 6 Dbd i 229 6 Dbc 6 Dbd 6 Dbe, 6 Dy~ 2 3&O 6 Dbd 6 Dbc, 6 Dbe 2 Dyb, 2 Dbd, 6 Dy K i 9~6 6 Dbe 6 Dbd 6 Db=, 2Dyb, 2 Ddb, 6 ~ i &~ 6 Ufd 6 Dyh 2 ~b 13 6 Ucb 5 Dye 6 Dyb, 6 Dyf ~9 6 Gnb 6 Dye 6 Dra Ill 6 Gnc 2 Dyb~ ~ Dyf 2 ~b, 6 Dye, 6 Dye 35A 6 Dra 6 Drb 6 Pyd, 6 Dy 8 271 6 Drb $ Dra, 6 Dyd 6 Dry, 6 Dy s ~4 6 Drc 6 Drb, 6 Dyf 6 Dyd , 2 Dyb. 6 DyE Z 953 6 Dye 6 Ucb, 6 Dyb 6 Dy~ 517 6 Dyb 6 Dye, 6 Gnd 6 Dy s 2 Z78 6 Dye 6 Dyd 6 Dyf, 6 DyS, 6 Drb 63 6 Dyd 6 Dye, 6 Drb 6 Dyb, 6 Dyg i 152 6 Dye 6 Dye, 6 G~c 6 Dy s 114 6 Dyf 6 Drc, 6 Dyd 6 Dyg+ 2 Dyb, 6 Ucb 8 470 6 Dy~ 6 Dyb 6 Dyf, 6 Gn= 459 TOTAL 75 568

Miscellaneous ~pplnE Dom%n~ Minor Area uni~ component soll proflle class (hectares)

R Areas of rock OU~C~p & Ucb, 4 Gnb 196 or sotls with excessive 5 ~e, 5 ~a ~unta of s~ne.

H Hi'Is too st~ep tO ~i~ cultlva~e, incl~din8 local ~un~In ~anS~s.

SP ~eas O~ Sw~ where Z Usd , 2 U8~ ] 740

run-off doe~ no~ occur, . E ~e~ of uns~ble erosion. V~rlou* 349

SF Sabine ~rlne flats.

DL 5urde~In del~i~ ~epo~z~.

G Grave~ deposits sufflclen~ 5 ~o p~even~ cul~iva~ion.

T~AL 4 80~ - 43 -

6. CHEMICAL AND PHYSICAL CHARACTERISTICS OF THE SOILS

6.1 Introduction

Laboratory measurements of soil characteristics provide a quantifiable reference base for many purposes. Within the survey area, 68 soil profiles representing 36 soil profile classes were sampled, as shown on the 1:100 000 soil map appended. Each site chosen had profile morphology close to median for the soil profile class it represented.

Each profile was sampled in i0 cm intervals to a depth of 150 cm. These were analysed in the laboratory according to methods described by Bruce and Rayment (1982). Three characteristics, viz. pH, water soluble chloride and electrical conductivity, were determined for each i0 cm interval. Soil chemical and physical properties known to affect or control soil behaviour were analysed at intervals: 0-10, 20-30, 50-60, 80-90, 110-120 and 140-150 cm. Chemical properties, related to transient soil fertility, were measured only in the 0-i0 and 10-20 segments. These intervals were chosen for agricultural or morphological significance, and involved 48 of the 68 soil profiles sampled. Detailed results are in Appendix 5b.

Within this section, analytical results are presented as eight logical groupings based on similarities of topographic form and profile morphology. Clay groups, A and B, comprise 38% of the total survey area. These groups include most of the gilgai sites. Duplex groups, C, D, E, F and G, comprise 46% of the sampling area, while the remaining group, M, contains the residue of profiles analysed. In group M there are 22 profile classes, which individually range in area from 5 to 2,340 ha and which represent a total of 16% of the sampling area. In terms of data interpretation at the level of a soil survey, this group cannot be meaningfully included, however the laboratory analyses ~re appended for completeness.

Groupings of sampled soil profile classes and the extent of analyses performed on each are given in Table 6.1(a). A summary of mean values or ratings for laboratory attributes for profile class groupings A to G is presented in Table 6.1(b). More detail is in Appendix 5a.

TABLE 6.1(a)

C.~mpw+.g+ o~ ~i ~ ~p~ ~ ~ ~ od ~ ~o~ o. ~

Group Soil profile krem involved Site n~berl ~scrlp~ion ~e~iEn~ion classes . na x ~0 ' S

C~CKING C~YS ~ A 2 Ugd, 2 U~e 21.6 ~2 ~, ~+, 5. 6 + , 7, Cr~ck~o~ cl~m o~ the £Ioo0 plain wz~h Light or 8 ~ , 9, !0, 47 light medi~ =l~y A horizon texture.

8 2 UKE. 2 UE~ ~.2 6 17, 18 + . 29. ~+, ,ZracMlng clays of t~e flood plain wx~ ~edi~ or ]8. 39, ~0, ~i , ~2 heavy clay A horxzon =ex~u~e.

DUPLEX ~IL5 C 2 Dbd+ 2 ~b 1~.6 21 :2 T 16. 21+ 3%. ~5, Solo~ics-soloelzed ~olone~z o£ ¢ne £ioo~ plain w%tn ~6 A norzzon deepe~ tn~ 12 cm ~d pPoflle s~ronKlY ~ikaline ~y 60 cm.

D 2 ~a. 2 Ddb 2.2 ~ 15~ 19. 22. 27. SolodZcs-~olo~ize~ solone~z of the flood plain ~8 , 5~ wi~n A bor%zon sballowe~ ~h~ ~2 cm.

E 6 DbO. 6 Dbe ~.3 5 33. )~. 36. 37. 63 Re~ bro~ e~hm on recen~ HauEbton River alluvial deposits.

p 6 ~a, 6 ~b. 2.~ W 2, ~9, 50, 51 +, Po0zolic soils on o~ne~ alluvial ~epo~t~ w~n A 5 ~d 52. 59 norizon 20 ~o 50 cm deep.

G 6 ~c. ~ Dyf ~.5 12 i. il. ~], ~a, 28 SoloOic8-8olo~ized solonerz on other alluvi~l ~epozi~s wlt~ A ho~izo. 20 to 50 cm ~eep.

~ ~SC~EOUS SOI5~ # ~ Gnb. 6 Gnb. 2 ~c, ~1.2 16 20, 23, 25, Indlvi~ual profile ~elc~ip~ions ~e ~xven in 2 D~c, 6 Dya, 6 Umb, 2W, 26. ~2, Table 5.i. 35~ ~), ~W. 6 Dbc. 2 UEI, 2 D~¢. 5 ~ , 55[, ~ ~b~ 6 Dy%, ~ DyC, 2 DDc, 56*, 57 , 5 Dy K , 6 Gnc, 2 Dbe, ~8¢ 60.+61 + , 62 . 6a , 5 ~e, 2 ~¢, • 6~, 66 +, ~UCb, ~ Ucc, ~ ~a, ~ ~J. 67 +, 68".

Analysed for pH, CI. EC only, all others analysed by =etho4s by Bruce and Ra~ent {1982~ except for methods 2.8) 2.10, 2.!!.1, 2.11.2 and 2.11.~.

~ Gxlgal:- Mound sltes - ~. 5) ?. 9, ~:'. ?g, 29. 98, aG, ~2~ ii~. ~?. l)e~resszon s~tes - ~, 6. S, tO, i~. 25. 30. 39. ~, ~. TABLE 6.1 (b) 5~L~ O~ Wean U~6~S or ~t~ags 0~ ~c~C.~l~O~ ~4~su~ed ~t~-~buczs L~ ~u~/:~e f9-~0 :~2 am~ two sub~ur~:ce z50-93 ~ 2~C-l~O cm~ ~p~As of so:l ~rofsZe c!:ss groupings A :o S s~c~us~ue

Soil Depth 5oi[ pH ~ater Sod lalty Ca/M 8 Exch cations Base Or B Total C;N Bicarb DTPA group (cm) soiuble ratlo saturation C N ratxo extract, trace e~ements Ci Ca Mg K % ~. equiv, i00 g-~ ) Mn Cu Zn

0~iO S[. v. low non sod~c 1.3 8.2 6.5 v. high 68 low low 14 v. iow ni%h reed. ~ed. ac £d A 50-60 M~Idly low sod~c i.I 14.5 12.6 medium 96 alko l&0-150 S=r. med lum strongly 0.9 i0 12 medium 98 alk. sodl¢

0-i0 Neutral v. low non sodlc 2.~ 17.~ 10.1 medium ~3 low low 15 v. low high med. med. B 50-~0 M~ldly low sodic 1.3 16.3 !3.2 medium 96 alk. 140-150 Sir. h~gh strongly 0.9 12.7 !3 medium 97 alk. sodic

0-I0 Sl. v. ~ow non sodlc 0.9 2.7 3.3 medium 51 low low l& v. low high me~. ~d. acid C 50-60 Sir. hlgh s~. sodlc 0.? ~.~ 13 low 99 alk. l&0-150 S~r. h%gh stronKly 0.7 6.& I0 low 99 alk. sod~c

• 0-i0 Neutral v, low sod~c 0.~ 3.0 &.0 medi~ 61 I~ {ow l& v. low high med. med. D 50-60 V. s~r. h~gn sir. 0.8 6.9 9.3 low 99 alk. aod~ l&0-150 V. sir. h~gh strongly 0.7 4.6 7.5 low 98 alk. sod~c

0-i0 $1. v. low non sodlc 2.3 4.I 2.0 medium 69 low low 19 h£~h h~gh mad. med. acid E 50-60 Mlld~y v. low non sodlc 1.7 i0.4 6.3 m~dlu~ 97 alk. 140-150 Hod. v. low sOdlc 1.9 9.G 5.0 low 99 alk.

0-10 SI. v. low non sodic 2.5 2.1 1.0 medium 56 low low !6 low high med. med. acid - neutral F 50-60 Neutra~ v. low ~on sodlc 1.6 6.5 &.l ~dtum 73 1&0-150 Neutral v. ~ow non sodlc 1.6 7.0 &.& med.um 91

0-I0 Med. v. low non sodi¢ 2.0 3.7 1.9 medium 55 ~ow Low 17 low high med. m~. acid G 50-60 Neutral v. low non sodxc 1.5 8.9 6.0 madi~ SO !40-150 Str. !ow sodic 1.4 i0 7.5 medium 99 alk.

6.2 pH

Results are presented as mean values with standard deviations (Table 6.2), because pH values are closely related to many other soil attributes, especially adsorbed ions. Special relationships between pH and other soil properties are highlighted under the relevant sections.

For all soils, mean surface (0-I0 cm) pH is 6.3 ± 0.6 (n = 68) (Table 6.2) and most soils have alkaline reaction trends at depth (Figures 6.2 a, b). The exception is soil group F, which has a neutral reaction trend. High standard deviations in groups A and B are associated with gilgai microrelief in these cracking clay soils (Figure 6.12(a) ). - 45 -

TABLE 6.2

M~an laboratory pH values and stan~d devi~ons a~ five deptks for seven groups (r~s~ expressed on a 40~C air ~ basis)

Soil Profile depth (cm)

group 0-I0 20-30 • 50-60 80-90 140-150 n

A 6.1 ± 0.5 6.7 ± 0.7 7.3 ± 1.2 8.5 ± 0.7 8.6 ± 0.5 9

B 6.9 ± 1.1 7.5 ± 1 0 7.9 ± 1.1 8.3 ± 0.9 8.4 ± 0.5 9 C 6.1 ± 0.1 7.1 ± 0 6 8.8 ± 0.5 8.9 ± 1.1 8.8 ± 0.5 6

D 6.6 ± 0.3 '8.8 ± 0 6 9.2 ± 0.4 9.4 ± 0.4 9.1 ± 0.6 6

E 6.2 ± 0.2 6.6 ± 0 2 7.6 ± 0.4 8.3 ± 0.7 8.3 ± 0.6 5

F 6.1 ± 0.3 6.3 ± 0 3 6.6 ± 0.1 6.7 ± 0.1 7.3 ± 0.2 6

G 6.0 ± 0.2 6.3 ± 0 1 7.0 ± 0.3 7.9 ± 0.4 8.4 ± 0.5 5

t number of observations for each depth interval.

In the laboratory, pH values ranged from 4.3 to i0.0. These were found respectively in an acid sulphate layer underlying a 2 Ugj class at site 68 and in the strongly sodic D horizon material underlying a 2 Dbd class at site 53.

Assuming that field determinations of pH will be made within the survey area, the relationship between field and laboratory values was investigated. A linear relationship (Y = 0.87 + 0.90X, r 2 = 0.86**, n = 408) was found between pH determined in the field (X) by the method of Raupach and Tucker (1959) and pH determined in the laboratory (Y).

F~g~e 6 2 ia~ $~J gH ~'Ohl@S ~Clay$) F,guee ~ 2 (~) SOil ~ ~Of~l ~ (~upl~ sO'l~) ,~es~ is ex~:es~ ~r a ~o C a," ~r. oas:s -e~:s exo~ess~ or. a ~3 C a." c',, oas,s:

;~ ~ ~ 6 ~ ~ '0 ~ 5 ~ : ~ ~ "o .o ..... -__

10 30 ~ ~, So~,c~-3o~o~o~e~:o~ '~ z~ '~ "N. ~*~ ~ 40 '1~ 31an ,C~ '~ ~ ~ ~ ~o:~.:s • so~,:~ '~ "~ ~ •. ~. ~ ~ ,~ C'~c~:nq clav~ ~ ~e,c..,z e' ~ ~ ~ -.~ ~ ..... ,,~ ~...... ~ , ~ "~ ...... :~ ~ ~ ...... " ~ ;:ae~.~ :;a~ ...... : ;, ~. "~" . ~x , ~ ,'o ~ "~e ,~ ~,a,~.~ • ~0 , :~::;,~ ~c, s ~ ~ ~'~ ~ ~ ~ ~o ~ ~ ~:~,~, .,, ~:o~.~ ~: ,~ ,~ ~

~o~,e~ • ~ ~: ~o~o~e,~ "-, ~ I ~ ~ ~---~ ~ ~,~, a i~,~, leoos,~ .al ~ ~. ~ ~ '~ .~ ~ "~ ,.o ~X .o : , '~ : ~ ~ .~, ~i t ,. 7 I' ,~o ~" ' i'P ':" ': i~ ....~50 1:, ,~ i :?.,: •

6.3 Salinity

Estimates of salinity hazard are derived from both electrical - c6nductivity (EC), which indicates the total soluble salt content, and chloride ion content. There was considerable variation between soil profile class groupings for both EC (Table 6.3(a) ) and chloride (Figures 6.3 (a, b) ). The intergroup va~iatlon becomes more marked with increasing depth. - 46 -

Using mean values at all depths, the specific relationship between EC and sodium chloride concentration (EC = 6.64 x %CI) was compared with fitted relationships. The linear model (EC = a + b %CI) is significant at the P <0.01 level within each of the soil groups (Table 6.3(b) ) except E where no chloride accumulations occur in the 150 cm of soil profile sampled. The low intercepts and similarities of slope to 6.64 are of practical importance because they indicate that chloride is the dominant soluble anion in these soils.

TABLE 6.3(a)

M~an values of ~lectrica~ conductivity (mScm-~ ) over five depth intervals for seven soil profile cla~s groupings (r~sulls expressed on a 40°C air ~ry basis)

Soil Depth (cm) group t 0-i0 20-30 50--60 80-90 140-150 n

A 0.044 0.031 0.190 0.411 0.504 9 B 0.070 0.063 0.198 0.386 0.726 9 C 0.031 0.147 0.6T4 0.827 0.602 6

D 0.040 0.361 0.942 0.988 0.707 6 E 0.022 0.024 0.040 0.054 0.040 5 F 0.018 0.010 0.013 0.010 0.021 6

G 0.024 0.020 0.034 0.080 0.164 5

t number of observations for each depth interval.

TABLE 6.3(b)

Lin~ function~ and coefficients of d~ermin~on (r ~ ) for r~lat~ons b~w~n chloride {CI; %) and ~lectrical conductivity (EC; mScm-~ ) for seven soil profile class groupings

wh~re the mod~ ha~ ~he form EC = a + b C1

+ Soil group n a b r2

A 54 0.04 9.22 0.97**

B 54 0.05 8.5 0.91"* C 36 0.04 8.36 0°94** D 36 0.06 8.65 0.96**

E t t t t

F 25 0.02 8.3 0.87** G 25 0.03 7.69 0.90**

+ n =' number of observations using air dry (40°C) soils. ** P <0.01. t no chloride accumulation. - 47 -

Based on criteria of Northcote and Skene (1972) the majority of soils studied can be classified as non-saline but some have a significant build up in soluble chloride at depth (see Figure 6.3 (a, b) ). Specifically, flood plain soils of groups A, B, C and D have appreciable chloride accumulations which may inhibit the growth of sensitive plants. By contrast, only minor accumulations of chloride were found in the profiles of soil groups F and G, so no plant growth problems are expected. Of the miscellaneous soil grouping, most had chloride profiles similar to those of soil groups E, F and G, although three sites (55, 6 Dye; 62, 5 Dye; 60, 6 Gnc) had some chloride build up at depth: at 50-60 cm, levels of 0.009~, 0.005~, and 0.011% CI, respectively were found while corresponding level&

at 140-150 cm were 0 . 051%, 0 . 067"~ and 0.022% C1 •

The shapes of curves in Figure 6.3(a) suggest that chloride concentration is at a maximum at 120-130 cm in group A soils and at 140-150 cm in group B soils, although maxima are not well defined. From Figure 6.3 (b), corresponding maxima for groups C and D are 0.095% at 90-100 cm and 0.1% at 80-90 cm. McCown ¢~t ~. (1976) and Mullins (1981) suggest that chloride levels in clay subsoils approach a maximum at the normal depth of . . wetting.

Gypsum can contribute to soluble salts in some situations but its presence in soils in this area is minimal. Only one profile sampled contained visible gypsum (site 69, 2 Ugj), and, except for two i0 cm segments of this profile, no total sulphur levels exceed 350 ppm S. Moreover., the 2 Ugj soil profile class is of limited importance, being only 5 ha of the total survey area of 80,000 ha.

F,9~e 5 3 (a) Chloe,de pcof,les. Icrack~n~ CIay$) F,g~e 6 3 (b) Chl~,d* 9rohtes (~uDlex SOIls) ,reS~l~S exor~s~ O~ a 40 C a:r ~ry oas S} ~-eSullS exDress~ ~n a 4C ~ a.r Cry bas,s~ ;, CI ~, CI ~ o2 03 3~ o5 ~ 07 O~ ~9 ic ol 02 03 O~ 05 ~ 07 oa o9 1o : I 10 I~V .... I0 ~% ~ ~ ~o ~.~... 30 I 30 ~ ~ ~o:.:" ~~ ~ Crac~,~;...... Clays ~ ~ ~ -~ ~. ~ 2'~Ck,e~ :lays ~

~0 ~ ~x of ~ae flo~ pla=n,BI 50 seionel: ~X~the ~ =~a~a~ ~ ~ ~ 50 50 x~ ~ 'l~ __ 1 C; m ~ & ~ "~ ...... ' { •~ m~ u~ ~am i~1 ~

g al.uv a: ~e~,~ tE~ N ~ ~ '0 ~ *''', ...... X al,~,al ¢e~s ~s ,¢; & ~ c ~0 ~ ~o ~ >___~ ~,c~-~o.~,z~ ~o~e~z ~ i ~ olhet ~l;~v,~ ~e~S;~S ,~) ~ / :~ ~ } ' ,~ ...... ~ ~ , ;, 2 I z7 i ,,o ,,o I , ~ ,~o ,~ ,~/

6.4 Cation Exchange Capacity, Exchangeable Cations and Base Saturation

Soil characteristics are significantly influenced by the exchangeable cations Ca, Mg, Na and K. The survey soils were tested for these and their total proportion of the soil cation exchange capacity (base saturation).

Direct determinations of soil cation exchange capacity (CEC) were made but the laboratory method used may overestimate these values wh.ere soils ame acidic, eg: 0-i0 cm depths from all groups except B. However, at depth most profiles are alkaline (Table 6.2). - 48 -

Mean profile trends for exchangeable ~a, Mg, Na and CEC for the major groups, A-G, are presented in Figures 6.4 (a-g). Because of low values of K (

The important ratios of Ca, Mg, Na and (Ca + Mg + Na +K) to CEC are summarised in Table 6.4(a). All soils, especially subsoils, are strongly base saturated, indicating that plant growth problems associated with A1 toxicity are unlikely.

TABLE 6.4(a)

Calcium/CEC ra~ios, magn~sium/CEC ra~ios, sodium/gEC ralios and base sa~a~ion f for s~v~n soil profil~ class groupings and lwo d~plhs (r~sul~s expressed on a 105°C oven d~y b~sis)

Profile Ca/CEC Mg/CEC Na/CEC Base t class ratio ratio ratio (ESP) saturation group %

0-i0 50-60 0-i0 50-60 0-i0 50-60 0-I0 50-60 cm cm cm cm cm cm cm cm

A 35 48 28 42 2 7 68 96

B 53 48 3O 39 2 9 83 96 C 20 31 25 46 3 28 51 99 D 22 28 29 38 6 39 61 99 E 42 67 21 39 1 3 69 97 F 36 42 14 26 1 2 56 73

G 34 44 17 30 1 3 55 80

i00 (Ca + M S + Na + K) CEC

Exchangeable Ca is the dominant cation throughout the profile in soil. groups A, B, E, F and G. Soil group C is dominated by Mg throughout the profile (Ca/Mg ratios less than l) while group D has Mg dominance in the upper part of the profile and Mg and Na co-dominance below 60 cm (Figure 6.4 (c, d); Table 6.4(a) ). High proportions of Mg and Na in groupings C and D would contribute to their poor physical properties. The Ca, Mg and Na contents of these groups are similar to those of ID, 2D, 3D and 6D solodic- solodized solonetz of the Burdekin right bank (Baker 1977).

Values for exchangeable K at selected depths as well as the ratio between exchangeable K and extractable K for 0-I0 cm depth samples are summarised in Table 6.4(b). Group M soils (Appendix 5) had exchangeable K levels >0.2 m. equiv, i00 g-i in the surface i0 cm except for profiles of 4 Gnb and 6 Gnb (sites 20 and 23 respectively).

Critical levels of potassium for plant growth based on exchangeable K are not well defined, but levels in surface soils below 0.2 m. equiv. 100 g-1 K have been associated with deficiencies (Williams and Lipsett 1950, Piper and De Vries 1960). From Table 6.4(b) it is apparent that all groups have inexcess of 0.2 m. equiv, i00 g-1 K at 0-I0 cm and that exchangeable K generally decreases with depth. This trend with depth is common to most Australian soils (Stace ~t ~. 1968) and was also observed in soils of the Burdekin right bank (Baker 1977). - 49 -

TABLE 6.4(b)

M~an val~s and standard deviations for ~xchang~abl~ potassium ~ fo~ ~pl~ for s~v~ so~ prof~ ~ groupings an~ ~ ~o o~ ~x~ble lo ~xc~ng~bl~ po~i~ in ~h~ 0-10 ~ prof~ segm~ of lh~ so~ (r~ ¢xpr~sed on a ~05~C oven ~ b~)

Profile Exchangeable potassium (m. equiv, i00 g-l) Extr K/E~ch K class ratio group 0-I0 cm 20-30 cm 50-60 cm 140-150 cm 0-I0 cm

A 0.54 ± 0.29 0.33 ± 0.12 0.26 ± 0.09 0.26 +- 0.12 0.76

B 0.49 ± 0.26 0.27 ± 0.16 0 28 ± 0.11 0.31 ± 0.07 0.91

C 0.34 ± 0.15 0.15 ± 0.02 0 16 ± 0.03 0.22 ± 0.05 0.76

D 0.44 ± 0.18 0.13 ± 0.01 0 14 ± 0.03 0.19 ± 0.06 0.79

E 0.40 ± 0.04 0.31 ± 0.06 0 28 z 0.08 0.16 ± 0.04 0.96

F 0.30 ± 0.06 0.19 ± 0.06 0 34 ± 0.ii 0.28 ± 0.04 0.98

G 0.41 ± 0.19 0.27 ± 0.16 0 38 ± 0.12 0.30 ± 0.09 0.78

On available evidence, including specific levels of exchangeable cations and relationships among them as well as with CEC, deficiencies of Ca, Mg or K are not likely to be widespread over the survey area.

Figure 6.4 (a) Calcium. Magnesium. Sodtum and CEC Figure 6.4 (b) Calcium. Magnesium, Sodium and CEC for SO~I group "A'. for soil group 'B'. (results expressea on a 105C oven dry basis) /results exoressed on a 105 C oven dry basis)

meq. ' 1009 meq. / 1009 o lo ~o ~o ,o o ,o ~ ~

20 ~ Ca 20 M9 30 30 ~ .

40 ~ 40 ~

50 50 ~

60 60 ~ Ca

~ ,o ~ ,o ~ ~

~ ,) 120 ] ~

/,/ 140 _ 150 I~ , - 50 -

Figure 6.4 (c) Calcium, Magnesium, Sodium and CEC Figure 6.4 (d) Calcium, Magnesium, Sodium and CEC for soil group 'C'. for sod group 'D'. (results expressed on a 105"C oven dry bas~s). (results expressed on a 105"C oven dry bas~s) meq. / 100g meq..,' 100g 0 10 20 30 40 0 10 20 30 40

10 10 "~~~'k'~\ ~

Ca 20 ~ ,,. Ca 20 ~ ~ ~ Mg ~ ~ ~ Mg ~o ~o ~ ~ ~~~ ",.. ~ ~o ~ ~ ~'~,..

50 ~ 50

~ ~o 6o I ~ ~o / _~ 7o ~ I { Q~ ,o / ~ ~o ~ 90 / 90

~ 1~

110 ~ 110 ,

130 ~~ " 130

140 ~ 140

150 ~ ~50

F~gure 6.4 {e) Calcium, Magnesium, Sodium and CEC Figure 6.4 (f) Calcium. Magnesium, Sodium and CEC for so~ group 'E'. for soil group 'F'. (results expresse~ on a 10S~C oven dry bas~s) (results expressed On a 105"~C oven dry bas~s)

meq / 100g meq. ,'100g 0 10 20 30 40 10 20 30 40

10 t ' ' 10

20 ~ Ca 20 _ Ca

--~ Mg ~ ~ Mg 30 ~ Na 30 , ~ Na / 40 ~ ~ CEC 40 ~,~ '~ 'L CEC

5O 5O \

60 60 ~ -~ ~ to " '~ 70 ~ =

~ 80 . - " ~o, 80 c ~0 90 ;

100 ¢ 100

110. 110

120 ~ 120

130. 130

140 140

"150 - 150 - 51 -

Figure 6.4 (g) Calcium, Magnesium, Sodium and CEC for so~l group 'G'.

- {results expressee on a 105~C oven dry bas=s)

rneq. / I009 10 20 30 ¢0

~o Ii\ c, ~ Mg 30 ~ , Na

40 . ~ ~. CEC

~° /

~ 7o ~8o i = / 9o I

100 ]

110 I

-120 - I I 130 I

140 I

150 [

6.5 Sodicity and Dispersion

Sodicity is an important soil chemical property that has been measured for this survey as exchangeable sodium percentage (ESP). Refer to Table 6.4(a) for mean values at two depths and to Figures 6.5(a, b) for profile trends in cracking clay and duplex soil groups.

Based on ESP standards of Northcote and Skene (1972), the 140-150 cm depths of groups A, B, C and D have the undesirable rating of strongly sodic (ESP >15) while deep subsoils of group G (120 cm) are rated ~ as sodic (ESF range 6-14). Soils of groups E and F were non sodic (ESP <6) throughout. Within the miscellaneous group M, profiles 58 and 60 (6 Dyg and 6 Gnc, respectively) were strongly sodic.

• F~gure 6.5 (a) E~xchangeable sochum g~'centage ;)follies. {clays) Flguce S S {b) Exchangeable S~ ~rcenta~ ~ronl~ (duplex soils) (results ~xo~ess~ ~n a ~05 C oven orv oas~s) ,reS~Hs expres5~ on a 105 C oven 3r~ oas~s; , ES~ ES~ 0 10 20 30 ~ 50 ~0 20 30 ~ ~ ~ ~"~'~ '~'~ i- '~,~on~...... ~' ' ,; .... ~ ,~ ...... ~,, .... ' l~i ~ '~ -~ ', ~: ' ~ ~ ~ ~ ,o'°} Xk' ~, ,o,o ,,. - ~ ~ ~ , ...... , " ., 50 : O 0 Cra~:ng ¢~ay$ ~ HI~ : ~ ~ ~ ~ = ~s ~ ~ ., ...... ,~ ~ ~ ~. ,"~ ;~L', " ~ SOl~tlN ~ ~ ~ X ~ ; ~ ~ fl~...... ~laln (C) X ~ ~ IX ,. ,~, --,-,o,.,,..... ,, ~ :~: /~ ~,~ ~ .... 1 ...... N~ ~r~ ,,~,elrt~ ~ -o '~ d~ts~ o,.., =.~,==t~) / ~i :..~ ot~...... llLuvI&L ~ ~e~sits (F! ~30. 130 T ~--.~ %~CS - S~I~Z~ [ :? 140 ...... Ot~r ~lL~wal ~ ~ de~s=ts (G) ~ ~ - 52 -

The tendency of soils to disperse in water has been quantified in terms of a dispersion ratio index (RI). Baker (~977), using the same dispersion ratio for soils of the Burdekin right bank, suggested R1 values should be interpreted as: R1 >0.8 as a high tendency to disperse (undesirable), 0.6-0.8 as moderate, amd <0.6 as low (desirable). Mean values and standard deviations for R1 values are shown in Table 6.5(a). All surface horizons are rated as having a low to moderate tendency to disperse with dispersion ratios generally increasing with depth. Exceptions are soils of groups E and F, which do not show an increased tendency to disperse with increasing profile depth.

There were high R~ values for groups C and D at or below 30 cm and for A and B at or below 150 cm. This high tendency to disperse should not be overlooked when planning irrigation water supply channels and land levelling operations.

TABLE 6.5(a)

. M£an values and stand~d deviation~ for dL~p~ion raZios (RI) for seven prof~£e cia~s groupings and four deplh~ (results expressed on a I05°C oven dry basis)

Profile " : Depth (cm) class .. .T ~ 0-i0 20-30 80-90 140-150 n group

A 0.58 ± 0°06 0.63 ± 0.07 0.71 z 0.07 0~79 ± 0.09 6

B 0.52 ± 0.13 0o61 -+ 0.13 0.79 ± 0.09 0.89 z 0.07 6

C 0.69 ± 0.05 0.80 ± 0.07 0.90 ± 0.04 0.89 z 0.06 5

D 0.56 ± 0.12 0.79 ± 0.ii 0.86 _+ 0.07 0.86 ± 0.06 5

E 0°64 ± 0°04 0.62 ± 0.09 0.54 ± 0.17 0.63 ± 0.23 5

F 0.58 ± 0.06 0.66 ± 0.05 0.45 ± 0.07 0.64 ± 0.ii 5

G 0°59 ± 0.i0 0.59 ± 0.12 0.65 ± 0.08 0.71 ± 0.03 5

t n = number of observations.

Relationships between sodicity (ESP and dispersion (R 1 ) were investigated using a linear model. For groups A-D, ESF accounted for a high proportion of R1 variance (ie: 49, 75, 86 and 72 ~ respectively). The relationship was less successful when data from all soil groups were combined) with EZF accounting for only 40% of Rt variance. In seeking other factors which may affect dispersion, such as exchangeable Mg, organic matter, clay mineralogy and soluble salts, it was found that Mg explained only a further 6% of the variance. Consequently, dispersion must be significantly affected by some other factor or factors.

Because tests for ESP and RI require significant laboratory resources, a simple means of assessing these interrelated soil properties was sought. The association between laboratory pH (1:5 soil/water) and ESP was examined and strong relationships of the form Y = a X b (where Y = ESP and X = pH) were confirmed (Baker ~t ~. 1983). Goodness of fit varied with soil group and was strongest for groups C, D and C/D combined (r ~ of 0.84, 0.87, 0.85 respectively). From the combined relationship for C and D, these groups would be expected to be non-sodic when laboratory pH was <6.5 and strongly sodic if >7.5. Corresponding field pH values are 6.2 and 7.5 respectively. - 53 -

Sink hole microrelief is frequently associated with soil profile class 6 Gnc (site 60). Highly dispersible material at the boundary of B and D horizons suggests (Appendix 5) that dispersed soil is removed in suspension causing collapse of the overlying material. The fate of the removed material is not known.

Since high sodicity in soils of the survey area is predominantly confined to subsurface horizons, alleviation by use of amendments such as gypsum or elemental S would be extremely difficult to achieve. Assuming quantitative substitution and similar replacement energies of Ca for Na in all soils irrespective of ESP, amounts of gypsum to reduce ESP by 1% at 50-60 cm varies with soil group (Table 6.5(b) ). Smith and McShane (1981) deal with this problem in some Lower Burdekin Valley soils.

TABLE 6.5(b)

Amount of exchangeable Na present when ESP = I, and calculated gypsum requirements to r~duce ESP by I ~ at 50-60 cm for profile class groupings w~th high subsoil ESP's

Profile class Exch. Na for ESP = 1 Gypsum requirement gr~u~. (CaSO~.2Hz0; kg/ha-lO cm) +

. .

•

A 0.31 428

I" B o13~ q69

C 0.28 386

D 0.24 331

Assumptions are that one ha-10 cm weighs 1600 t and that 1.38 tonnes of pure gypsum will exchange 1 m. quiv. Na/ha-10 c~.

6.6 Plant Available Water Capacity

Stored water contents of various soils differ and this affects the amount of soil water available for plant growth, as well as influencing irrigation mangement. The plant available water capacities (PAWC) of soils in this survey have been examined.

Shaw and Yule (1978) used the laboratory measured -15 bar water content to estimate gravimetric water at the upper and lower storage limits. These estimates are converted to volumetric soil water using a calculated bulk density and then sl,mmed over the plant rooting depth. Estimates of plant rooting depth given in Table 6.6 were derived from the chloride profile, corresponding to the depth of maximum rate of change of soil chloride concentration or depth to C horizon (Figures 6.3 a, b).

For comparative purposes, PAWC calculated from -15 bar laboratory measurements and those from the difference between laboratory determined -i/3 bar and -15 bar (available soil water capacity) are given in Table 6.6. Mean values of PAWC from the seven groups are given for the two methods, together with average plant rooting depth and the estimated number of days between irrigation events. Table 6.6 shows that laboratory FAWC values are much higher than predicted PAWC values for all groups with the greatest discrepancy in groups that have highest PAWC. Use of the laboratory method has been severely criticized on the basis that -i/3 bar values seriously overestimate the. upper storage limit in many soils (Gardner 1971, Loveday 1974, Gardner and Coughlan 1982). - 54 -

TABLE 6.6 Av~ag~ PAWC by two. different m~hod~, av~ag~ rooting d~plh and days belw~n irrig~ons for groups A Io G

Average Rooting Predicted Laboratory Depth (R.D.) PAWC I PAWC 2 Days between Soil (cm) to R.D. to R.D. Irrigation 3 group Mean Range (cm) (cm) (N)

A 80 (60 - I00) 12.3 22 14

B 80 (5o - I00) 13.1 29 15 c 50 (40 - 60) 8.9 13 i0

D 40 (30 - 50) 7.4 8.5 8

E i00 'C' Horizon 12.0 26 14

F I00 'C' Horizon 13.7 22 15

G 90 (80 - Ii0) 12.9 23 15

All values reported on I05°C oven dry basis.

1 Method of Shaw and Yule, 1978.

2 -i/3 bar and -15 bar water contents converted to volumetric water via calculated bulk density in I0 cm increments. Differences were then s~mmed over average rooting depth.

0.75 x PAWC ] 3 N = days (see Gardner and Coughlan, 1982 p. 6). 0.95 x 7

The Burdekin left bank cracking clays (Table 6.6) have a PAWC range of 12.3 - 13.1. This compares with cracking clay PAWC ranges of 10.5 - 13.3 (for B and Tb groups) at Emerald (Shaw and Yule 1978) and 9.2 - 15.0 on the Burdekin right bank (Gardner and Coughlan 1982).

The sodic duplex soils, groups C and D, have a PAWC range of 7.4 - 8.9. This compares with sodic duplex soil PAWC value's of 6.0 - 10.5 at Emerald and 7.7 - 8.4 on the Burdekin right bank.

In land management terms, PAWC values are used as an indicator of:

the frequency of irrigation. The values (days between irrigation) shown in Table 6.6 are comparable with those of Gardner and Coughlan (1982) for cracking clays (Groups A and B, 14 - 15; Gardner and Coughlan, 14) and sodic duplex (Groups C and D, 8 - I0; Gardner and Coughlan, 8).

ranking of soils for ease of management. Sigh PAWC requires less management input. Using this, the survey soil groups can be ranked as B>P>G>A>E>C>D.

deep drainage and nutrient leaching potential, when considered in conjunction with profile peaks of chloride. The sodic duplex groups (C, D).have low PAWC values and shallow chloride peaks. The remaining soil groups have higher PAWC values and chloride peaks at considerable depth - suggesting faster infiltration rates, deeper profile wetting and possible deep drainage under irrigation. ,. - 55 -

6.7 Clay and Clay Activity Ratio

Trends in clay percentage for clay and duplex groups are shown in Figures 6.7 (a, b, c).

Flguee 6.7 (a) Clay I)ercenta~ p,or,=es. (clays) F,~]ure 6.7 (b) C~ay ~rcenta~e grohles. (duolex so=Is) tresults express~ on a 105 C oven 3ry 3as,5) ~resu:~s ex~essed oq a "05 C oven 3rv has=s1 Clay % Cma~ ~: 35 ~ ~ 50 55 50 3 10 20 30 ~ ~

io ~ ~ ~o ~ ~ ~ 20 ~ " ~~ ~

' 30~ ~ ~ .::~,.~,.v~ , .o30 jJ~ .... ~,~,cs-som~,ze~ somone(z ~'~X x i,J of ~e =m~ ~ma,n(A) 50 ot ~ne tm~ O,aln ~C) ' - o o C:acKm@ clays . 60 ~ ~ ~ ~,~,3s - so'~z~ solone¢z 60 of (~e fl~ pta,n(8) . of ~e ~1o~ grain (~) / ~,o _ ~ / , ~J / // ~ / ,~ / / / ~o " ,~o ] /

i30 / -~ ~0 ~ / / ~SO ~ 1~ ,, ~

F=g~e 6.7 (¢) Clay ~rcentage ;wohles {~ther duplex) (results ex~resse~ on a ;05 3 oven ~ry D~S.~)

Clay ~= 0 10 20 30 40 ~ 60 ~ ---.:~ ~0 ~ ~ .~ ~ ~-.. ~ x..... x ~ ~o~ ea~thstE% ~% "-.. ~ "'..

~ . .~ ...... ~ / . ~

~---~ Sohd,cs -SOI~,z~ ~ I solonetz ~ // t ~ other x / ~ ~llu~=al i /~~ ~ 4e~os,¢s / ~ ~G) / ~ / ~ / ~ 120 ~ 130 ~ ~ kXk 7 / 140 k 1~ =

Clay contents in all groups relate well to field texture extimates. All soil classes show a tendency for clay contents to increase initially with depth and then to decrease. This decrease is usually related to presence of D horizons. The decrease is irregular in group E soils where evidence of layering is often found, possibly indicating that group E soils are younger than the rest (because profile development has not been sufficient to mask layering in the lower horizons).

The clay activity ratio can provide information on dominant clay minerals in a soil. Table 6.7 gives clay activity ratios in clay or duplex groups at three depths. The 0-i0 cm depth is omitted because CEC and clay values were low and the contribution to CEC by organic matter is likely to be highest in this segment. - 56 -

TABLE 6.7 Clay activity r~ios (CEC g-lof ~lay) for seven soil .profile cla~s groupings and three dep~h~

Profile class Depth (cm) group 20-30 50-60 80-90 •

A 0.56 0.58 0.60 B 0.64 0.64 0.64

C 0.59 0.59 0.61

D 0.62 0.62 0.65 - E 0.68 + 0.58 0.86

F 0.47 + 0.32 0.33 G 0.45 + 0.39 0.46

+ A horizon material may be present in some profiles.

Clay activity ratios range from 0.13 at site 20 (4 Gnb) to 2.01 at site 23 (6 Gnb), thereby covering the whole clay content spectrum, ie: kaolinite (clay activity ratio <0.3), i:i lattice.minerals or illite (0.3 -- 0.4), and 2:1 expanding lattice minerals (>0.6).

Groups A, B and some sites within M have clay activities >0.6. Some confirmation has been provided by Coughlan (1979) who found that A horizon material with a clay activity ratio of 0.62 from a 2 Ugd site (within . our group A) contained: interstratified expanding layer silicate (or poorly crystalline montmorillonite), kaolinite, quartz, illite and interstratified kaolin-montmorillonite.

The B horizons of groups C, D and E also appear to be dominated by expanding lattice minerals while those of groups F and G are probably dominated by i:i lattice minerals or illite.

6.8 Total-P and~K

Measurement of total-P and K in soils can provide information useful to the understanding of processes which have occurred in soil development. They also indicate present 'reserves' of these elements in soils.

Total phosphoru~ values wer~ found to be quite variable between profiles within a single soil group, especially at depths below 80 cm. This is indicated by standard deviation of means in Table 6.8.

SurfaCe horizons of all soil groups (except E, F) had higher total-P levels than subsoils (50-60 cm). This probably relates to contribu- tions to the P pool from soil organic material. Group E soils have highest total phosphorus levels (above 0.04%; Table 6.8) of which acid-extractable phosphorus accounts for 8 to 15%. Total phosphorus in other groups is generally less than 0.03%, acid-extractable phosphorus accounting for only 2 to 4% of this. - 57 -

All groups (except E and F) show an increase in total phosphorus in the deep subsoils (compare 50-60 with 110-150). Similar increases in a cracking clay soil on the Burdekin flood plain (similar to groups A and B) was previously reported by Reid (1978). He found this deep subsoil phosphorus extractable by acid but not bicarbonate solutions and suggested that it was in the form of apatite minerals which have low plant availability. We assume the same situation applies to similar soils of this survey. Figures 6.8 (a, b, c) show depth trends found for total phosphorus.

TABLE 6.8

M~an total-P l~v~ls (%; I05°C oven dry) and standard d~vi~ons al five d~plh intervals for s~v~n soil profile ~£ass groupings

Profile Depth (cm) class group 0-10 20-30 50-60 80-90 140-150

A 0.029±0'.005 0.017z0.003 0.016±0 003 0.019zO.Oll 0.037±0.030 B 0.020±0.005 0.015±0.003 0.014±0 003 0.014±0.003 0.029±0.016

C 0.031±0.018 0.019±0.007 0.016±0 002 0.023±0.007 0.028±0.01~

D 0.028±0.004 0.018±0.003 0.017±0 003 0.023±0.010 0.029±0.013 E 0.047±0.005 0.038±0.011 0.048±0.024 0.044±0.010 0.038±0.012 F 0.025±0.004 0.018±0.002 0.038±0 017 0.033±0.016 0.025±0.010 G 0.040±0.029 0.023±0.005 0.020z0.003 0.025±0.002 0.034±0.005

Figures 6.8 (d, e, f) illustrate the mean total potassium profiles for all groups. Lowest total potassium levels occur in the flood plain clays of group B while the highest levels occur in group E.

Little and Ward (1981) suggest that total potassium in soils formed on alluvium decreases with increasing age of the soil. We suggest (see Section 4.2) that group E soils are amongst the youngest in the survey area. However, their high total K status cannot be used to confirm this because of likely differences in potassium content of alluvium from the Burdekin and Haughton Rivers (Reid, Baker and Cannon; in preparation).

6.9 Extractable Phosphorus

Mean values and standard deviations of extractable phosphorus for all soil groupings at 0-I0 and 10-20 cm (for both methods of analysis employed) are summarised in Table 6.9. Except for group E soils where acid- extractable P levels significantly exceeded those for bicarbonate-extractable P, both methods provided similar estimates of soil P status. - 58 -

Fl~-e ~.8 {a) Total pho~,ph~s ixoflle$. {clays) F~ure ~.8 (b) Total ~.os~or~ ~ohles {duplex soils) ~esu~s ex~esse~ on a '05 C ore, ~r,i bas,s) ~es~l~s exp~esse~ on ~ I0~ C ore. ~v bas~s;

Tota, OnOSDbO~JS % To~al pbOSDbOr~5 % ,01 02 .03 .04 35 0 01 ~ 33 ~ ~

,o ~ ~ ~o ~/~ ~o ] ~- ~ ( Cr~Cklng C~ays ~ "40 Qf ~n~ fl~ ~lal~(A) ~ x~ ~ SOI~ICS-5OI~IZ~Solone~z ~f ~e i ~o~ plain ~C) 50 / / o o C ...... g ..... 5C ~ S...... ~,z, of ~e flq~ piaCn(B) ~ ~ ~ Solone:z Ot :he 50 ~ ( 50 ~ x~ f'~ p,aln (O) ~ ,o t~ ~ ,o ] ~ ~ ao I ~ ~ ~o~ ~k

~ ~ ~ xN =.o ~~ ~ .o J 'Xx ,~o ,~o 1, ~Xx/ , 130 13C ~ ,,o ,~ ~.~ 150 1 150 [

Figur~ 5.~ [¢) Total phosphot~ ~oflles. ~otM~ duplex) Fig~e 6.8 (d) Totai potassium profiles. {clays) K~esul:s exoress~ on a 105 C oven dry bas,s~ {~esults exoresse~ on a '05 C oven ~ry oas~s)

T~lal o~osphoru5 % To~al po:asslum % ~ 01 32 ~ ~ O~ 1 0 1 5 2.~ 2 S I ,o ~ ~~~~-~ / /~ ~0 ~ 20 ~ ~ ~ /~ 20 / 30 ~ x~ 30 ~ , ...... • ..... x ~ ~O~ eart~s~E) / x ~ } X X Ol t~e fl~ pla~) . / ~, ( ' 50 ~ ~ °~z°uc so,,s: ~ j o ~ CracK=ng clays x ol the 11o~ olam So,~,cs -~o,~,z~ , ~,o ~ ...... ~,~ ~ ~ ~o ~ ...... , ~l / xS ~ / ~ "i ,./,. ~ ~

,~o ~ ~ , ~ 120 ~ ~ ~ ~ 110 ~30 ~ 120 ~40 ~ / 130 ~so ~ ~ ~ ~o

150 ~ ~ Figure K.8 (e) Total gotasslum p~Oflles. (duplex soils) F~g~I 6 8 (f) Tolal ~tasslum ~ot~les (ot~¢ duplex) ~resui'.s exoress~ 3n a ~05 C oven Cry basis) :~es~ls express~ On a '05 C cven dry has,s} Total ~/ass,~m % To~al oolass~um =~ 0 I 0 ~ 5 2.0 2 ~ ~ O 1 5 2.¢ 2.5 3£

,o ~i ,o~, ~, ~ ~ ~ X----X S°I~ICS'$OI~IZ~solonetzOf ~ne 40 1 ~..... , n~ brown ear¢~s~E) i ~ ~ ~ tIo~ Olain(C) ~ ' ~ ~ ~ ~ ~l~cs- Soa~,ZK ] / ~' -;', so~onetz...... ot {he 50 ~ ~ ~ ~zohc so~,s{F} ~ ~ 70 J ~m~cs-so~,z~o som~etz ~ ~, x 70 ~ ~ ~-'-~ ~ ot~er ~:~uv,al ~epos,ts ~Q) ~ " ~,o ~, ~ ~ , ~ ~" ~ ~ ~ x '~ k~ -o ~ ~ ',, ,,o.

~20 • ~30 =I 130 { ~ ',0 ; ', ~40 :~ [ 6 / ,,o ;~ - 59 -

TABLE 6.9

Mean a~id and bic~Abonat~_-exlractabl~_ phosphor~ l~_u~2.s and - stand~d derivations a~3 0-10 and 10-20 cm for profile #~£a~s groups A to G (r~_suI~ts ~xpr~sed on a 40°C air dry basis)

Profile class Acid-P ppm Bicarb-P ppm group 0-i0 cm 10-20 cm 0-i0 cm 10-20 cm

A 7 +_ 4 3 ± 2 8 +- 5 4_ + 2

B Ii _+ 15 5 _+ 3 4 ± 2 2 ± 1

C 4 -+ 2 2-+ 1 7-+ 4 3_+ i_

D 5 +_ 4 2_+ 2 7_+ 4 2_+ 1

E i01 ± 85 69 _+ 75 44 ± 21 22 ± 14

F 12 z 6 4 z 4 13 z 5 5 z 3

G 17 -+ 22 4 _+ 3 18 _+ 21 5 _+ 3 j."

Extractable phosphorus is low to very low in all groups except soils on alluvial deposits associated with the Haughton River (E). All group M profiles associated with Haughton River deposits have high extractable phosphorus levels similar to those for group E and reflect the relatively younger age of this alluvium (see section 4.2). All other ungrouped (M) profiles show low to very low values. Mean extractable phosphorus in the 0-i0 cm zone over all soils is 24 ppm by acid extraction and 19 ppm by bicarbonate extraction.

. Apart from the soils on young alluvial deposits, soils on the right bank also have low extractable phosphorus (Baker 1977).

There are limitations of empirical tests in estimating ? availability for specific plants. Consequently, they can only be considered to give a broad overview of P fertility for these soils. Field experiment- ation needs to be undertaken before P fertilizer measurements and management options can be detailed. It is suggested such studies be undertaken before irrigation development takes place.

6.10 Carbon, Nitrogen and Sulphur

Group mean values and standard deviations for organic carbon (unadjusted Walkley and Black) and total-N (both to 20 cm), together with C/N ratios (carbon unadjusted) for 0-i0 cm depths are given in Table 6.10(a). - 60 -

TABLE 6.10(a)

Mzan v~es and standard deviations for organic carbon and ~otal-N ~ two depths for seven profile c~ass groupings and mean C/N ratios for surface horizons of the same soils [r~suI~ts expressed on a I05°C oven dry basis)

Profile Organic C% Total N% C/N Ratio class group 0-I0 cm 10-20 cm 0-I0 cm 10-20 cm O-10 cm

A i.i ± 0.19 0 7 ± 0.Ii 0 08 ± 0 02 0.05 ± 0.01 14

B 0.9 ± 0.22 0 6 ± 0.08 0 07 ± 0 01-. 0.05 ± 0.01 15

C 1.0 ± 0.24 0 8 ± 0.09 0 08 ± 0 02 0.06 ± 0.01 14

D 0.9 ± 0.09 0 8 ± 0.19 0 07 ± 00l 0.06 ± 0.02 14

E 0.9 ± 0.24 0 7 ± 0.13 0 05 ± 0 02 0.04 ± 0.02 19

F 0.7 ± 0.18 0 5 ± 0.17 0 04 ± 0 01 0.02 ± 0.01 16

G 1.0 ± 0.35 0 6 ± 0.13 0 06 ± 0 02 0.04 ± 0.01 17

Organic carbon levels are low in all surface horizons (mean i.I ± 0.19 %C; n = 48), and decline with depth (10-20 cm: mean 0.7 ± 0.11; n = 48). A similar rating in 0-I0 cm horizons applied to total-N but by 10-20 cm, levels in most soils had declined to very low levels. The range at 0-I0 cm was 0.04 to 0.08% N while at 10-20 cm no soil contained >0.06 %N.

When combined as C:N ratios, the mean value for both 0-I0 and 10-20 cm horizons was in the range 14 - 19, indicating limited prospects for significant N mineralization in these soils. In comparison, C:N ratios more commonly associated with arable land fall within the range of I0 to 12. Implications are that significant N fertilizer inputs will be required for non-leguminous crops and pastures at a very early stage of development.

Total-S at two depths as well as C:N:S ratios at 0-i0 cm are given in Table 6.10(b) for groups A to G.

TABLE 6.10 (b)

Mean v~zs and stan~d deviation~ of tolal-S aZ two depths and C:N:S ratios in s~face (0-10 cm) samples for seven profile class groupings (resuIls ~xpressed on a I05°C oven dry basis)

Profile class Total--S% C:N:S group 0-I0 cm 50-60 cm 0-i0 cm

A 0.017 ± 0.004 0.010 ± 0.001 133: I0: 2.1

B 0.013 ± 0.002 0.009 ± 0.005 145: I0: 2.0

C 0.012 ± 0.003 0.015 ± 0.006 135: i0: 1.6

D 0.012 ± 0.004 0.019 ± 0.008 .137: i0: I~8

E 0.010 ± 0.002 0.007 ± 0.001 167: I0: 1o9

F 0.008 ± 0.002 0.007 ± 0.002 189: i0: 2.2

G 0.013 ± 0.004 0.007 ± 0.002 154: I0: 2.0 - 61 -

All groups except C and D had higher S in the surface horizon~ suggesting some association with organic matter. It is generally accepted. that total-S is a poor predictor of soil S deficiency. However, guidelines given by Andrew q~ ~D~. (1974) indicate that responses to S could occur on soils with <0.013% total-S, suggesting that deficiency of this element is a future possibility on soils within groups C, D, E and F. In practice, heavy applications of phosphate fertilizer to these soils can be expected both to displace adsorbed sulphate and reduce the capacity of surface horizons to adsorb additional sulphate ions (Blair 1979). Irrigation development coupled with alkaline pH trends at depth will encourage leaching of sulphate-S and increase the chances of S deficiency.

Mean C:N:S ratios reported (Table 6.10(b) ) are similar to those found on the Burdekin right bank and Proserpine lowland soils (Baker 1977; Thompson, Baker and Cannon 1981). For comparison, levels for other North Queensland soils have been reported by Crack and Isbell (1971) and Probert (1977).

6.11 Trace Elements

Means and standard deviations for DTPA extractable trace elements in surface soils are listed in Table 6.11.

TABLE 6.11

M~an v~lu~s and standard deviations of DTPA ~xlract~ble copper, zinc, manganese and iron for su~fac~ (0-I0 cm) samples of sev~nsoil profile class groupings Ir~su~ expressed on a 40°C air dry b~is)

Profile class Cu Zn Fm Fe group (ppm)

A 2.3 ± 0.24 i.i ± 0.56 81 ± 25 93 ± 26

B 2.2 ± 0.69 0.8 ± 0.55 55 ± 29 88 ± 50

C 1.6 ± 0.53 1.0 ± 0.47 62 ± 27 86 ± 19

D I.i ± 0.32 0.6 ± 0.21 54 ± 24 73 ± 26

E 0.7 -+ 0.19 2.4 ± 0.77 54 ± I0 91 ± 16 F 0.7 ± 0.33 2.4 ± 0.65 63 ± 9 59 ± 19 G 1.0 ± 0.19 2.4 ± 0.55 61 ± 17 66 ± 12

Copper values were commonly medium (Bruce and Rayment 1982) but groups E and F were lower. Based on findings with tropical pastures legumes (Bruce 1978) deficiencies or toxicities of Cu are unlikely to restrict plant growth in these soils. - 62 -

Availability of Zn is influenced by factors such as soil pH, phosphate supply, and soil Eh potential. Ratings vary with soil pH but most fall within the medium range. Nevertheless, mean levels for group A, B, C and D were sufficiently low to be considered marginal, especially in the presence of added phosphorus. Fertilizer trials on a 2 Ugh soil (a gilgai within group B) with 2.0 ppm DTPA Zn,. showed no response to Zn using paddy rice (Maltby, unpublished data). However, it is possible that deficiencies could be induced as a consequence of high fertilizer phosphate dressings needed to sustain high rice productivity.

• Manganese levels were commonly

DTPA Fe levels were reasonably consistent throughout. These data have been included for information purposes only, as interpretation of this test on Queensland soils remains uncertain.

6.12 Properties of Gilgai Soils

Gilgai profiles sampled within cracking clay groups A and B and group M (2 Dyc, 2 Ddc [depression] and the 2 Ugi [mound] site) have been detailed in Table 6.1(a).

Many soil properties such as pH, clay percentage, clay type and nutrient status are known to vary between mound and depression areas of gilgaied soils (Thompson and Beckmann 1982; Beckmann and Thompson 1960; Hallsworth ~ ~. 1955). Variation in these properties were also apparent (Figures 6.12 a, b, c, d) in gilgai soils of this survey.

Beckmann and Thompson (1960) indicated that crop management of a gilgai soil following levelling would be a problem for 4-5 years. Because of differences.in pH (Figure 6.12 a) and to a lesser extent clay activity ratio (Figure 6.12 d) a similar situation is likely to occur in these Burdekin soils. Local experience (J.. Maltby, personal communication) has already shown that variable extractable P status (2.3 and 7.0 ppm bicarbonate- extractable P in mounds and depression, respectively) is a problem when gilgai soils are levelled for rice production. The findings that mounds had both higher pH and much higher clay percentages (figure 6.12 c) throughout the profile support the view that they were former subsoils.

Evidence that a stronger leaching enviz~onment currently exists in the mounds comes from their greater mean depth of wetting (115 cm for mound and 85 cm for corresponding depression; Smith and McShane 1981) and the fact that Figure 6.12 shows the peak EC lower down the profile in the mounds. Lower clay activity ratios (Figures 6.12 d) in the mounds probably indicate the presence of i:i lattice clays and suggest a stronger leaching environment.

With these variations in soil chemical and physical properties, crop management problems following land levelling are likely to remain for at least the time period suggested by Beckmann and Thompson (1960). ~63 ~

i I~ i

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~ o

o ~ ~ ~

• i ~!

c~ ~ • ~ ~ • - 64 -

7. AGRICULTURAL LAND USE

?.I Present Land Use

7. I. ~ Irriga~.~d

Irrigation development in the survey area is generally confined to levees of the Burdekin and Haughton Rivers and adjacent flood plain areas. Sugar cane is the most important crop with minor areas of seed beans and small crops on levee areas. Rice is grown on the flood plain where water is available.

Minor areas adjacent to Horseshoe Lagoon and Barratta Creek and at Lochinvar have been developed for rice and sugar cane using underground water supplies.

The expansion of irrigation in the area is limited by available water supplies.

7.1.2 D~y~d

The greater part of the area is used for cattle grazing with low levels of management inputs.

Small areas have been developed for sorghum, lab lab beans, soybeans and pumpkins. These developments are generally confined to soils of topographic form 6 where irrigation water is not available. Expansion of the area used for dryland agriculture is largely limited by:

Unreliability of rainfall.

Lack of suitable sorghum varieties for the environment.

Fauna problems, particularly brolgas and wild pigs.

7.2 Changes with Increased Availability of Irrigation Water

Increased availability of irrigation water is likely to have the following effects on land use:

Allow development of land currently used for grazing.

Allow crops to be grown over the dry season.

Give stability to wet season crops due to supplementary irrigation.

Increase yield of crops presently grown under dryland conditions.

Allow expansion of the area under crops presently growo with irrigation (rice, sugar cane) '.

Allow the introduction of new crops (cassava).

The suitability o'f the area for irrigation development, is, however, dependent on climate, topography, drainage, flooding, soils and crop suitabi]ity and management. - 65 -

7.3 Environmental Limits to Irrigation

.. 7.3. I C/~mo~

The climatic variables of temperature, day length, sunshine (light intensity) and rainfall all impose limits on irrigated cropping in the area.

As the area is essentially frost free, frost susceptible species can be grown throughout the year with little risk of damage. Low temperatures, however, cause sterility in rice crops which flower during cold weather and they have been blamed for the poor winter production of pangola grass pasture~.

Day length limits the varieties of soybeans suited to the area and limits planting times for suitable varieties to December and January. Day length also limits the performance of sorghum as existing varieties are not adapted to tropical conditions.

It has been asserted (Burdekin Project Committee 1977) that the generally higher yields of winter planted rice as against summer planted rice are the result of lower light intensity when the summer planted crop is maturing. Barnes and Reid (1978) found that a summer planted rice crop yielded 30% less than a winter planted crop receiving similar treatments and management. The summer plan.ted crop received 40~ less bright sunshine than the winter planted crop between panicle initiation and grain filling and it is suggested that this caused the yield difference. Murata (1975) showed that solar radiation or sunshine hours between booting, after panicle initiation, and grain filling was an important climatic factor limiting rice growth.

Rainfall will affect irrigated land use by necessitating storm water drains to remove run off and erosion control measures to prevent land degradation. It will also delay or prevent farm operations such as harvesting or planting. The impact of the latter on rice cropping has been examined by P.G.H. van Beek (unpublished da~a) who mathematically analysed the relationships between five management strategies and rainfall probabilities. Some of his data is presented by Thompson (1977).

7.3.2 Topography

Mapping units surveyed can be allocated to the following five slope categories:

a) Flat, slopes 0 to 0.2%. Mapping units: 2'Ugd, f; 2 Dyc.

b) Flat to gently sloping, slopes 0 to 0.5%. Mapping units: 2 Uge, g, h, j; 2 Dbc, d, f; 2 Dyb; 2 Dda, b, d.

• c) Flat to moderately sloping areas, slopes 0 to 2%. Mapping units: 1Uge; 1Dba, b; 2 Ddc - 2 Ugi; 6 Ucb, 6 Uma, b; 6 Ufd; 6 Gna, b, c, d; 6 Dra, b, c; 6 Dbb, c, d, e; 6 Dya, b, c, d, e, f, g.

d) Sloping areas, slopes 2 to 5%. Mapping units: 4 Ucb, c, e; 4 Gnb; 4 Dyd, 5; 4 Dga; 5 Dra; 5 Dyc, e.

e) Steeply sloping areas, slopes >5%. Mapping unit: H.

The topography of categories a) and b) is well suited to rice cropping. Slopes are generally even and they are such that rice bays can be constructed with acceptable bay widths and within-bay falls. Levelling will be required to remove minor surface irregularities and gilgai microrelief. At slopes above 0.5%, the banks of rice bays occupy an unacceptably high proportion of the area. - 66 -

The higher slopes in category c) areas are generally short so serious rainfall erosion problems are unlikely in category a), b) and c) areas. S~riou~ ~rosion may, however, occur wh~re local or stream over-bank flood waters f~ow at high rates. Pa~ of the banks and beds of st~ active d~tributory chann~ may n~ed to be left under native veg .e.tat~on to prev~nl t~i~ ~osion. An instance of it occurred in February 1978 when over-bank flow from Barratta Creek eroded I0 to 15 cm from about 4 ha of a fallowed block on the bank of a distributory channel at AMG Zone 55K: 517700 E, 7820500 N.

Areas in slope category d) will have significant erosion hazard when developed. Some gullying occurs on the topographic form 4 area and minor areas of tunnel erosion are evident on the area of 5 Dye in the undeveloped state. Erosion control structures such as contour banks and grassed water- ways will be needed to cope with rainfall and irrigation run off. Where soils are suitable for surface irrigation, furrows should be run across, not down, the slope. The feasibility of this has been demonstrated on an area of 5 Dra mapping unit by W.J. McDonald (unpublished data). Areas in this slope category generally have sufficient surface stone to necessitate from one to four stone pickings during development.

The H mapping unit in slope category e) has been separated because its steep slopes make it unsuitable for irrigation development.

7.3.3 Surface drainage ..i

_ A coordinated drainage scheme forms an integral partof any irrigation scheme. Excess surface water must be removed to prevent waterlogging and trafficability problems and excess subsurface water must be removed to prevent the eventual incursion of water tables into the crop root zone.

Surface drainage must remove excess irrigation water, local storm run off and flood waters once overbank flow ceases. ~ d2~ge 0~% most of the a~a is through broad based depr~sions, construction of an extensive d~nage sysZ~m w~ be necessary.

On individual farms, accurate levelling to provide even and adequate slopes and the planting of row crops on substantial hills will be necessary to avoid crop damage from waterlogging.

It will be necessary to provide drainage for excess surface water throughout the area but the problem becomes most acute on flood plain a~eas where slopes are lowest.

7.3.4 Subsurface d~nage

The occurrence of shallow saline ground water tables and the failure to make adequate provision for the control of them has been a major problem of large scale irrigation schemes (Langford-Smith and Rutherford 1966).

Important aspects of ground water hydrology are the depth to water table, water quality and seasonal and long term changes in these para- meters. Table 7.1 summarises water quality and depth data available from some of the Queensland water Resources Commission test bores in the alluvium. Most of the area is underlain by water tables at 1.5 to 15 m and generally deeper than 5 m. Quality of this water is variable but it is generally of at least medium salinity hazard (Richards 1954). The worst quality waters are generally close to the saline marine flats and reflect times of higher sea level when the coastal interface was further inland as discussed in section 4.2.3. - 67 -

TABLE 7.Z ~hcer CUc~CV, ~3rc~¢.~. ~fc ~r~ cr¢c

1.100 000 Australt&n Map LO8 Depth to D~pch :o ;a~er depth Elect. Cond. SA8 *~ N~° R.$.C. + P~¢~n8 ~ ~pCn 8 unlt Cr~d ~eference- ~u~ber sand b~drock ~alow &round ~$ Cm "~ ~eq L "~ ~e9 L -~ ~) ~ ~ E ~

8 ~yf 512820 7~2150 ~:~C00~5 ~.~ 3.~.~ 1530 8.9 L0.53 0 C3-51 b ~yf 515470 ;841~20 ii~0~0~6 a.5 3.~6 12000 22 9~.39 0 C~-Sa ~ U~d 518250 78&~3&O i1900047 ~.! 2.~9 5000 iZ )2.5~ 0 Ca-S& 6 ~mb 510990 18~7280 11900059 ~.21 830 10 33.~ 3 C&-S3 6 byf 5119~ 7837150 11900060 32 3.5Z :0500 29 85.59 0 C&-S& 2 ~b 514230 7S36870 i19C0061 72 ~.12 6~0 3.~ 3.91 !.~ C2-SI 6 ~yf 511100 7835480 11900054 4.34 1850 15 16.96 7.3 C3-53 6 Dbc 510300 7833600 I1900066 Z6 8.31 790 1.7 2.83 0.5 C3-31 5 Drc 514~80 7833600 ~1900068 8.33 670 O.& 0.43 0 CZ-SI 6 Pyf 512200 7829860 I1900069 10.37 ~00 l.i 1.26 0.2 C~-SI 2 U~d 510800 7S25700 11900074 Zl 6.21 490 1.9 2.2~ l.C C2-SI 6 Dya 516300 7836~60 11900088 5.35 500 3.8 3.04 2.2 C2-SL 6 Dyf 511750 783&0~ 11900089 [3 26.5 ~.18 ilCO ii i0.13 5.2 C3-52 6 Oyf 514140" 7829~20 11900095 38 11.7 790 4.~ 5.65 ].8 C3-51 6 9b~ 51C~0 78~75~ [1900099 10.86 S95 6 Dbc 5~6~20 78236~0 i!90010~ 8.86 5~ 6 Um~ 508080 7~21820 ~900105 4.34 ~]0 6 D~ ~O~20 ~8207Z0 [1900110 10.74 545 , 2 ~b ~998~ 7816~00 i19~!16 i&.19 380 , 6 Dbc 4993~ 78148~ i19~i18 i&.62 350 * 6 ~c 4966~ 7814500 11900121 14.5 ~i0 6 Drc 518680 7838500 i19001~5 ~.~ &;O

6 Dbc 5!43~ 782~180 )9813 6.28 ~250 6.~7 4.09 3.38 C2-SI ~ Drb 518730 7814400 11910025 20 36 13.26 ZICO 6 Drb 517050 7S15200 !191002S 17 36 13.17 3~ Z Dyb 515430 7814180 i191~29 14 27 7.0~ [!9 2 Dyb ~27660 7~1880 ~!910051 4.~ 1.67 ~O0 ii 30.54 0 C~-5} SP 531300 7~0~0 11910052 1.5 2.25 l~30 14 13.75 O.~ C3-$3 2 U~d 526500 ;837120 11911057 7.6 4.76 1260 3.5 g.~ 0.2 C3-31 Z ~b 5305ZO ;837900 i19~0058 18.3 3.8 ~5 2.9 ~.35 0.5 C~-Si DL 531940 7~331~ I1910069 ii.0 ~.~ 6.8~ 255 1.7 1.3 0.9 CI-Si DL 531500 78301~ I19100~2 54.9 6.52 ~55 1.7 Z.26 0 C2-51 Z Dyb 526100 7827150 [1910106 7.9 45.7 9.53 i~0 2.5 ~.13 0 C3-SI 2 D~ 5293Z0 7826~G 1191010 ? 7.~ 3300 7.3 17.83 0 C&-53 DL 532060 ?835160 I19101~8 4.96 345 1.3 i.~ 0.4 CI-SI 2 Ush ~18!50 7812~0 1191017~ [9.5 22.5 12.54 70~ 2 Ugh ~18180 7808070 11910176 16.5 Dry Dry 6 DTf 517850 7803750 [1910178 i0 15.2~ 5300 2 Ugd 516300 7319320 [1910179 [3.5 20 10.85 ~90 Z Dye 518~60 781~230 iig!Ol80 11.6 23 i0.62 780 2 ~b 5ZO73U 7819460 i1910!~2 10.6 20.6 11.65 1400 2 U88 518320 7819580 119101~3 11.5 30.5 13.4 200 6 ~f 520750 78&09~ 119101~ 6.0 3.2 9950 Z.Z 78.3 O C&-~ 5P 5239~ 7~0780 !!910185 3.0 1.73 459 6.1 3.91 l.g C2-51 6 Drc 5176;O 7836~ 1191C186 23.8 ~.8 7.]5 ~ 1.7 1.83 0.5 C2-SI 2 Ugd 5203~ 783~250 I1910188 15 .I ~O.5 5.2 320 1.5 1.39 0.& CZ-Sl 6 Dbe 5220~ 7816100 llgiO~fl9(A) 55.5 5.95 290 ~.6 2.31 i.I C2-SI ~ Dbd 524820 78369~0 11910191 5.~ ~I0 0.4 1.74 0.i C2-Sl 2 Ogd 527660 78372~O 11910192 3.00 2800 7.8 17.75 0 ~-$2 SB 530160 7817160 i191019~ 1.71 300 2.5 l.T& 0.3 C2-51 Z Ugd 5172~ 7832340 i191019& 6 24 4.i 350 !.4 1.3 0 C2-S1 Z 3yb 521410 7831920 i19~O195 !7.5 ~7 7.58 225 0.9 0.7 0.5 Ci-Sl 2 Ugd 52~0 7831460 !1910196 17.5 ~ 7.35 300 1.8 1.65 0.5 C2-51 ~ Uge 5286~ 7830980 11910197 8 39.5 5.1~ 1200 Z.0 I.S3 O C2-51 6 Dy~ 515860 78295Z0 [~9~0198 8 31.5 9.61 ~0 1.7 !.65 O.& CZ-Sl ~ Dbc 518100 789250 !1910199 !5.6 ~ 9.69 [55 l.i 0.57 0.3 CI-51 ~ Dyb 520680 ~827760 :1910200 6 35 5.69 81 2.5 0.4 0.2 CI-SI ~ Dyb 517650 7822260 ~1910204 5.3 20 9.7& 98 0.9 0.83 0 C2-SI ~ ~b 520~ 7821~90 11910205 8 25 .B 3.57 ~15 2.2 2.0 0.9 C2-SI 6 Dyf 516220 7833100 i19~02!0 10.2 38 7.91 330 3.4 2.39 Z C2-51 ~ U~d 5192;O 7832130 11910211 5.~9 330 A.5 2.78 1.5 C2-51 ~ U~e 527700 7835!20 11910234 5.13 400 ~.~ ~.61 1.2 CI-SI S~ 5Z7580 7839520 ~1910251 3.37 54700 Z& 3Z7.97" 0 C&-~ 2 Dbd 51~I00 78161~ ~ILL 730 3.i g.~ ~.8 C2-3~

6 ~ 522330 7797&50 ~20000Ag ~9.63 ~30 6 Dbb 526~ 78213~ 120001~ 13.3 ~4.0 Ii.93 2600 2.3 6.~ 0 Cg-Sl 6 O~ 528660 78~!080 120~I01 20 24.5 17.21 510 2,6 2.35 0.85 CI-51 2 Oyb 5233~0 7~17050 ~2000~32 Z& 12.89 ~930 Z U~ 520210 78~2210 120~77 10.5 ZI g0.&6 730 6 ~d 523340 780~ 12000178 18.8 27.5 14.35 1640 2 ~$~ 520560 78089~ i2~OlSl 19.5 16.02 2450 6 ~c 5156~ 7815750 120~195 10.35 1700 6 Dya 519910 7815450 12000196 ii 27.5 12.51 i~0 6 Dya 5234~ 7818010 12000198 12.59 955

+ ~e ~K ~C - Res~du~ S~i~ Ca¢~naEe ~ ~*

Rlt~n~. AS in USDA ~d~ok N~be~ 60. "OtaKnosts ~d ~¢ov~e.~ of Saline and A~k~i Soils," P~e ~0. - 68 -

Behaviour of these aquifers under increased irrigation development is impossible to predict with certainty. However, they probably represent old stream channels and many of them may have outlets to the sea or existing streams. This may prevent water tables rising into the crop root zone under irrigation. T~S ~spec~ requires f~h~r investigation.

Thompson (1977) has summarised observations of ground water movement down slope and salt accession in lower slope positions on areas of topographic form 5. AS W~ as minimizing waler inputs on these slopes, it may be necessary to provide d~ainage for seepage waters at the foot of slopes affected. Shallow water tables and seepages have been observed on topographic form 4 so similar precautions may also be needed there.

7.3.5 Flooding

The frequency and extent of flooding in the survey area.was discussed in section 4.3.1. Flow velocities will not cause erosion or lodging of other than mature crops except in isolated areas. Rice, sugar cane and soybeans are resistant to damage from inundation at most growth stages but other crops may be severely damaged.

Flooding is most likely in December, January, February and March. November flooding could damage mature rice and young plant or ratoon sugar cane, while April flooding (which has been recorded) could damage mature rice, sugar cane, and soybeans, as well as other s1~mmer crops.

It may be necessary to prohibit cropping in some of the natural broad drainage lines and to ensure that roads and channels across them do not restrict flood run off. It may also be desirable Co prohibit dwelling construction in some of the more flood prone parts of the area and recommend that machinery parking areas and sheds be elevated.

7.3.6 Son

Soil Variability

Soil variability was discussed in section 5.4. It causes management problems when the distribution of soils with widely differing management characteristics is such that they cannot be cultivated as separate management units.

While soil variability may make irrigation management difficult in a number of parts of the surveyed area, the areas involved only % exceed about 50 ha in two locations. These two areas are defined by AMG Zone 55K: 514000 E, 7831000 N; 517000-E, 7831000 N; 517000 E, 7828500 N; 514000 E, 7828500 N and 510000 E, 7818000 N; 511000 E, 7815500 N; 506500 E, 7814500 N; 507500 E, 7817000 N. The area involved at each locality is approximately 750 ha and in each case apparent prior stream channels cause soil distributions so complex that irrigation development should not be considered until a more detailed soil survey has been undertaken.

V~riable crop performance is often associated with the locations of old mounds and depressions in levelled gilgaied areas and with sodic duplex soils. These variations appear to be associated with low fertility after removal of the surface soil from the mounds, and with differgnces in water entry characteristics (G.D. Smith, personal communication). In most cases, they disappear after a number of crops particularly if adequate fertilizer is applied.

Crop Water Use

Thompson (1977) gives estimates of the irrigation requirements of various crops on a range of soils in the area. Supplementary irrigation requirements for a number of crops have also been estimated by Burdekin Project Committee ~1977) and Burdekin Project Assessment Committee (1978). - 69 -

Major differences between soil profile classes in supplementary irrigation requirements for any crop may occur because of differences in deep drainage loss6s and run off losses at irrigation. Deep drainage losses will be governed by soil permeability. Soil morphology and chemistry allow the soil profile classes to be placed in loose groups with increasing permeability as follows:

(a) 2 Dda, b.

(b) 1Dba, b; 2 Dbc, d, e, f; 2 Dyb; 2 Ddc.

• (c) 1Uge; 2 Ugd, e, f, g, h, i; 2 Dyc.

(d) 4 Dyj; 4 Dga; 5 Dyc, e; 6 Gnc; 6 Drc; 6 Dbb, d, e; 6 Dye, f, g, h.

(e) 2 Ugj; 2 Ddd; 4 Dyd; 5 Dra; 6 Uma, b; 6 Ufd; 6 Gna, d; 6 Dra, b, 6 Dbc; 6 Dya, b, c, d.

• . (f) 4 Ucb, c, e; 4 Gnb; 6 Ucb; 6 Gnb.

Deep drainage water losses for any crop will be least on group (a) soils and greatest on group (f) soils. The permeability of soils in groups (a), (b) and (c) should be low enough for rice to be grown without excessive water use while that of soils in group (f) may be so high that irrigation by surface flow is impossible.

Irrigation run off losses will be determined by frequency of irrigation and infiltration pattern. Irrigation frequency will be lowest on soils with the highest plant available water (see glossary) and G.D. Smith (unpublished data) has investigated plant available water in a number of the soil profile classes. Plant available water of different soil profile classes is discussed in section 6.6. Infiltration pattern will determine the time for which it is necessary to have free water at the soil surface to obtain full replenishment of the soil water deficit.

7.4 Crop Suitability and Management

Soil-crop suitability and necessamy management practices are determined by the factors discussed in section 7.3 and by soil chemical and physical characteristics.

Table 1.2 summarises crop suitability, environmental limitations and management problems for the soil profile classes. This table was compiled by assumin~ presently available crop varieties and levels of management technology.

7.5 Land Capability Classification

Burdekin Project Committee (1977) presented an irrigated land capability classification of the area based, on the mapping units of Hubble and Thompson (1953). Because this survey has mapped the area in more detail and because the Burdekin Project Committee (1977) classification does not take the special requirements of rice into account, a land capability classification has been undertaken for this survey.

The I:I00 000 mapping units have been allocated to land classes according to their suitability for crops other than rice and according to their suitability for rice and the allocations are shown in Table 1.4. Appendix 9 gives details of the classification schemes used. Table 7.2 shows the areas of the various classes. - 70 -

TABLE 7.2

Ar~as of zach land ~l~ss from ;:100 000 mapping units

Class Crops other than rice Rice

Area (ha) % of total Area (ha) % of total

Class 1 Nil - 15 837 20

Class 2 12 477 15 12 949 16

Class 3 45 445 57 15 145 19 Class 4 16 114 20 12 832 16

Class 5 1 532 2 18 805 23

Miscellaneous 4 804 6 4 804 6 units

7.6 Estimated Sugar Cane Yields

Sugar cane yield estimates have been made for the I:I00 000 mapping units of Thompson's (1977) survey and this survey (Thompson and Reid, unpublished data). These were obtained by grouping mapping units thought to have edaphic similarities and by obtaining cane yields over a number of years from the sugar mills for blocks on as many of the mapping units as possible. Table 7.3 shows these estimates, a suitability ranking and the major limiting factors for sugar cane.

When data were being collected, Cane Inspectors emphasised the importance of attention to management detail in obtaining good yields on soils ranked 3 and 4. They were of the opinion that astute and experien- ced cane growers on these soils could obtain yieZds at or above the dfstrict average of 125 t ha -I with techniques such as frequent and timely irrigations and cultivating more frequently than would be necessary on rank 1 and 2 soils. These factors imply that production costs will be higher on the lower ranked soils. Yields on many soils ranked 3 and 4 are likely to be lower in the first few years as farmers develop the necessary management skills.

8. ENGINEERING CONSIDERATIONS

8.1 General

This section brings together some of the information from field and laboratory work that may be useful to those planning or executing engineering projects within the survey area. Because of the scale of the survey, it cannot be used to make positive predictions about conditions at specific sites. It is intended to be used in conjunction with soils maps to indicate where certain problems may be encountered or where useful materials may be found. Information for each of the i:i00 000 mapping units is summarised in Table 1.3. - 71 -

TABLE 7.3 Estimated sugar cane yislds, ~ui~ability ra~king and li~itin4 factors for I:100 GO0 mapp%ng units

Mapping units Estimated cane yleld, Suitabil~ty Major limiting** and likely range ( ) ranking factors for cane t ha "~

1 Dba Salinity 2 Ugj Low available water 2 Dda, b, d - 5 Drainage problems 6 Ufd Trafficabili=y 6 Gnc Flooding

2 Ugd, f 90 + ~+ 4 f, d, t 2 Dyc (40-140)

2 Ddc - 2 Ugl 90 '~-~ ~ f, d, t, v (60-120)

2 Oge, g, h 95 + ++ 4 f, d, t (40-140)

1 Dbb 95 + ++ ~ f, a 2 Dbf (40-120) 2 Dyb 6 Dyg

4 Uce I00 3 f, v A Dyd, j (60-120)

2 Dbc, d I00 + ++ 3 f, t, a 5 Dyc (80-120) 6 Drc 6 Dbe 6 Dye, f

A Ucb, c ii0 + 3 f, w A Dga (70-150) 6 Ucb 6 Dya

5 Dra 120 + 3 f, w, r, e 5 Dye (80-140)

6 Dra, b 125 + 2 f 6 Dbb, c, d (80-200) 6 Dyb, c, d

4 Gnb 150 + 1 f, e 6 Umb (i00-200) 6 Gna, b, d

i. Well suited to sugar came production. 2. Suitable for sugar cane with minor topographic and/or edaphlc llmztauione. 3. Suitable for sugar cane wlth moderate topographic and/or edaphlc limitations. .4. Marginally suitable for sugar cane with major topographic and/or edaphic limitations. 5. Not considered suitable for sugar cane. ,-~ Ma~or Limi~in~ Factors

f - fertility, soils will require P and K as well as N. d o poor surface drainage. . t - surface texture such that difficulties in working moist or dry so~l m~y be encountered. v - soil variability. a - available water limited through limited roo:ing depth. w - shallow water tables or seepage areas may develop. ~ r - stone pickings required. e - erosion.

+ Yield data obtained for a~ least one sugar cane block on a mappin~ unit in this edaphi¢ group. This may have been for one of the mapping units of Thompson (1977) or for-one from this survey. ++ Production over the first five years of cropping ~%ay be up to 20 per cent lower as management skills develop.

: - 72 -

8.2 Expansive Clays

Murtha and Reid (1976) list the most obvious engineering problem associated with the soils of the Townsville area as that associated with expansive clays. These clays create design problems for building and road foundations and can cause fracture of non-flexible pipes.

Problems are likely on mapping units dominated by gilgaied soils (all 2 Ug plus 2 Ddc - 2 Ugi, 2 Dyc and 1Uge). Of these soil profile classes, those with the heaviest surface textures (2 Ugf, 2 Ugg, 2 Ugh and 2 Ugi) exhibit the strongest cracking and self mulching characteristics. Some other areas of duplex soils of topographic form 2 (2D's), particularly 2 Dda and 2 Ddb, exhibit surface cracking so their subsoils may also contain sufficient montmorillonite to cause soil swelling and shrinkage.

8.3 Highly Dispersive Clays

Highly dispersive clays can cause engineering problems through accelerated erosion /n S~ and through the failure of embankments and road foundations constructed from them (Murtha and Reid 1976). Highly dispersive clays generally have high levels of exchangeable sodium.

Dispersion ratios for sampled profiles are discussed in section 6.5. It appears that clays in soils of topographic forms 4, 5 and 6 are of moderate to low dispersibility with the following exceptions:

the subsoil of soil profile class 5 Dyc (Thompson 1977).

the subsoil of soil profile class 5 Dye which is subject to tunnel erosion.

the deep subsoil of soil profile class 6 Gnc which has a high dispersion ratio and is subject to sink hole microrelief.

the subsoil of soil profile classes 6 Dbb (Thompson 1977) and 6 Dyg which have high dispersion ratios.

Subsoils of all soil profile classes of topographic forms 1 and 2 contain highly or occasionally only moderately dispersible material. Highly dispersible material is closest to the soil surface in the duplex soil profile classes, particularly 1 Dba, 1Dbb and 2 Ddb where it occurs as shallow as 30 cm.

8.4 Corrosion of Underground Services r

According to Murtha and Reid (1976), galvanised steel pipes can corrode very rapidly when they are laid in B horizons of duplex soils that are highly alkaline, have moderate to high exchangeable sodium and moderate salt levels. These conditions occur in the B and D horizons of all topographic form 2 duplex soil profile classes (2D's),~as well as in those of soil profile classes i Dba, i Dbb and 5 Dyc (Thompson 1977), 6 ~yg and in the D horizon of soil profile class 6 Gnc. The likelihood of pipes being laid in material with these characteristics is greatest in soil p~ofile classes with shallow A horizons and strongly alkaline pH close to the surface (2 Dbd, Dba) and is least where A horizons are deeper an~ strongly alkaline material is lower down the profile.

Lindsay, Scheelar and Twardy (1973) using data of the United States Bureau of Reclamation state that some types of concrete may be severely attacked in soils with greater than 0.5% sulphate. Gypsum crystals were observed in some profiles of soil profile classes 2 Ugh, 2 Ugj, 2 Dyb, 2 Ddb and 2 Ddd, so high sulphate l~vels can occur in some parts of the flood plain. Olson (1973), however, states that concrete corrosion is worst in acid soils with high sulphate so it may be important only where soil profile classes 2 Ugj and 2 Ddd overlie cat c~ays.

8.? Potentially Useful Deposits

The beds of both the Burdekin and Haughton Rivers contain deposits of sand (0.0.2 to 2 mm), gravel (2 to 75 mm) and cobble (?5 to 250 mm). Stream bed deposits occur in Barratta and Oaky Creeks as well but these are rarely coarser than sands.

Deposits of gravel were also observed in auger borings, gravel pits or stream beds at the following AMG locations (all Zone 55K): 515400 E, ?835100 N; 522650 E, 7832300 N; 513300 E, 7831800 N; 515000 E, ?831400 N; 514000 E, 7831000 N; 516250 E, ?826350 N; 51460~ E, 7812200 N. These deposits would generally contain less than 25% of material finer than 0.02 mm in diameter.

The subsurface horizons of soil profile classes 4 Ucb, 4 Ucc, 4 Uce and 6 Ucb would generally contain less than 15% of material finer than 0.02 mm so these mapping units may also contain material useful as aggregate.

The topsoil and subsoil of each profile sampled for detailed analysis are classified according to the Unified Soil Classification (P.C.A. 1962) in Appendix 8.

9. ACKNOWLEDGEF[ENTS

The authors wish to thank Mr. R.C. Mcdonald, Department of Primary Industries, Brisbane, for assistance and advice during all stages of the project and Messrs R.C. Bruce and B. Powell for editing the manu- script.

Former Department of Primary Industries officers, Mr. M.G. Cannon gave extensive assistance with the field work and Mr. W.P. Thompson gave much useful advice. Officers of Department of Primary Industries Ayr, Messrs J.E. Barnes, E.A. Gardner, J.E. Maltby, W.J. McDonald and M.C..Finlay provided advice on the Land Use section. Dr. G.D. Smith now of Departmeht of Primary Industries, Toowoomba also provided advice on the ,. project.

We gratefully acknowledge soil analyses carried out by the Soil Chemistry Laboratory Staff.

The Queensland Water Resources Commission, Townsville and Claredale, are thanked for providing data on ground water and flooding.

The management and Cane Inspectors of Invicta and Inkerman Sugar Mills are thanked for providing cane yield data for specific blocks.

Special thanks are due to Leanne Stead who accurately prepared the enclosed maps, the typists who prepared various drafts, particularly Christine Lynch.

I0. GLOSSARY

A2~/u~ ~n: The deposit of sediment laid down by streams as they enter open plains or open valleys. The stream bed ends in fan shaped deposits (Thompson 1977).

C~z~n£~ /n6~: Infilled beds, fan formations and sand splays of past distributary drainage lines (Thompson 1977). - 75 -

Flood ~lain splay: Deposit of sandy or gravelly stream bed material on a flood plain in a fan shaped deposit where excess water leaves the stream through a restricted break in the natural levee. The velocity of escaping water has been sufficient to carry coarse materials further from the channel than would other- wise be the case (Happ ~ a~. 1940).

Lo~ a~l~ui~l-coll~uia~ pla~s: A depositional plain composed of alluvia and less severely weathered sediments (colluvial) derived from

local hills (Thompson 1977). •

Mapping ~: An area or group of areas coherent enough, to be represented to scale on a map, which can be adequately described in a simple statement in terms of its main soil profile classes (Beckett and Webster 1971).

Mi~ror~£izf: A repeating pattern of surface undulations, usually gilgai.

PZant Av~l£ Watcr Ca~acily: The soil water in the active root zone available to the plant (Thompson 1977).

P~a~ prof~ form: The primacy division of soils based on textural changes down the profile (see Northcote 1971).

Prior s~rgams: Infilled beds and associated levees of past stream courses (Thompson 1977).

Soil profi~ c~S: A group or class of soil profiles, not necessarily contiguous, grouped on their similarity of morphological characteristics. (Beckett 1971; Beckett and Burrough 1971; Beckett and Webster 1971; Burrough ZZ a~. 1971). As mapped, they are representative of bodies of soil with similar parent materials, topography, vegetative structure,.and generally vegetation composition.

So~ prof~£ cla~s - dominant: The soil ~rofile class that occupies .>70% of a mapping unit area.

[opog~h~c fo~m: An areal entity representing generalized uniformity of topography and geomorphology (Thompson 1977).

[~n~l £ro~io~: The erosion by water of subsoils while normally leaving the surface material intact over much of the affected area (Thompson 1977).

ii. REFERENCES

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AUSTRALIAN BUREAU OF METEOROLOGY, ~UEENSLAND REGIONAL OFFICE (1970) - Climate, Burdekin, Townsville Region, Queensland. Resources Surveys. Department of National Development, Australia.

BACHS, W. (1976) - The measurement of Cation Exchange Capacity of Soils. lou2u~al of ~hz S~£ncz of Food and Agri~z.

BAKER, D.E. (1977) - Chemical and Physical Properties of the Soils. In "Soils of the Lower Burdekin River - Elliott River Area, North Queensland." Queensland Department of Primary Industries. - 76 -

BAKER, D.E., RAYMENT, G.E. and REID, R.E. (1983) - Predictive relationships between pH and sodicity in soils of tropical Queensland. Commun/- cationS in Soil S~ence and Plant Analysis, Volume 14, Number i0.

BARNES, J.E. and REID, R.E. (1978) - Effect of mid-season draining on paddy rice in the Lower Burdekin Valley. Q~£znSland Journal of Ag~i~12~u2u~l Animal $6i£nc£ 35 : 159-67.

BECKETT, P.H.T. (1971) - The cost-effectiveness of soil survey. 0~00~ in Agricultur£ 6 : 191-8.

BECKETT, P.H.T. and BURROUGH, P.A. (1971) - The ~elation between cost and utility in soil survey. IV. Comparison of the utilities of soil maps produced by different survey procedures, and to different scales. ]ouAy~l of Soil S~cZ 22 : 446-80.

BECKETT, P.H.T. and WEBSTER, R. (1971) - Soil variability: A Review. Soil~ Fert~£iz~t~ 34 : 1-15.

BECLMANN, G.G. and THOMPSON, C.H. (1960) - Soils and land use in the Kurrawa area. Queensland C.S.I.R.O., Soils and Land Use Series No. 37.

BLAIR, G. (1979) - "Sulphur in the Tropics." The Sulphur Institute and International Fertilizer Development Centre: Muscle Shoals, Alabama.

BLOOM, A.L., BROECKER, W.S., CHAPPELL, J.M.A., MATTHEWZ, R.K. and MESOLELLA, K.J. (1974) - Quaternary..sea level fluctuations on a tectonic coast: New 23°TH/23~U dates from the Huon Peninsular, New Guinea. Qu2J~£n~zy R~souA~£s 4 : 185-205.

BRUCE, R.C. and RAYMENT, G.E. (1982) - Analytical methods and interpretations used by the Agricultural Chemistry Branch for soil and land use surveys. Queensland Department of Prima~y Industries, Bulletin QB 82004.

BRUCE, R.C. (1978) - A review of the Trace Element Nutrition of Tropical Pasture Legumes in Northern Australia. Tropical G~sla~d~ Vol. 12, No. 3.

BURDEKIN RIVER AUTHORITY (1951) - The Burdekin River Irrigation, Hydro- Electric and Flood Mitigation Project, 1951.

BURDEKIN PROJECT COMMITTEE (1977) - Resources and Potential of the Burdekin River Basin, Queensland. Australian Government Publishing Service, Canberra.

BURDEKIN PROJECT ASSESSMENT COMMITTEE (1978) - Report on Burdekin River Project. Queensland Government, Brisbane 1978.

BURROUGH, P.A., BECKETT, P.H.T. and JARVIS, M.G. (1971) - The relation between cost and utility in soil survey. I. The design of the experiment. II. Conventional or free survey. III. The cost of soil survey. JouA~ of Soil Sc~Z~6Z 22 : 359-94.

CHRISTIAN, C.S., PATERSON, S.J., PERRY, R.A., SLATYER, R.O., STEWART, G.A. and TRAVES, D.M. (1953) - Survey of the Townsville-Bowen region North Queensland, 1950. C.S.I.R.O. Australia, Land Research Series No. 2.

COUGHLAN, K.J. (1979) - Influence of micro-structure on the physical properties of cracking clay soils. Report to Reserve Bank of Australia.

CLARKE, M.P., WASSON, R.J. and WILLIAMS, M.A.J. (1979) - Point Stuart Chenier and Holocene sea levels in Northern Australia. S~/~tc~ I0 : 90-2. - 77 -

CRACK, B.J. and ISBELL, R.F. (1971) - Studies on some neutral red duplex soils in north-eastern Queensland. I. Morphological and chemical characteristics. AU.S~n JouAna~ of EX~@WL~m£~ Agri~ugt£ Ar~ma~ Husbandry ii : 328-335.

GARDNER, W.R. (1971) - Laboratory measurement of availble soil water, gox~ Science Society of America Proceedings 35 : 852.

GARDNER, E.A. and COUGHLAN, K.J. (1982) - Physical factors determining soil suitability for irrigated crop production in the Burdekin-Elliot River Area. Agricultural Chemistry Branch Technical Report No. 20.

GREGORY, C.M. (1969) - Geology of the Ayr 1:250 000 sheet area. Report Bureau of Mineral Resources, Australia. No. 128.

HALLSWORTH, E.G., ROBERTSON, GWEN. K. and GIBBONS, F.R. (1955) - Studies in Pedo Genesis in N.S.W. VII. The 'Gilgai' Soils. Soi~ gc~zn6£ 6:1-31.

HAPP, S.C., RITTENHOUSE, G. and DOBSON, G.C. (1940) - Some principles of accelerated stream and valley sedimentation. United States Department of Agriculture Technical Bulletin, 695.

HOPLEY, D. (1970) - The geomorphology of the Burdekin delta, North Queensland. James Cook University of North Queensland Department of Geography, Monograph Series. No. i.

HOPLEY, D. (1974) - Investigations of sea level changes along the coast of the Great Barrier Reef. In Procedures Second International Coral Reef Symposium. 2 : 551-62.

HOPLEY, D. and MURTHA, G.G. (1975) - The quaternary deposits of the Townsville coastal plain. James Cook University of North Queensland Department of Geography, Monograph Series. No. 8.

HUBBLE, G.D. and THOMPSON, C.H. (1953) - The soils and land use potential of the Lower Burdekin Valley, North Queensland. C.S.I.R.O. Australian Soils and Land Use Series. No. i0.

ISBELL, R.F. and MURTHA, G.G. (1972) - Vegetation, Burdekin-Townsville Region Queensland. Resources Surveys. Department of National Development, Australia.

LANGFORD-SMITH, T. and RUTHERFORD, J. 1966) - "Water and Land." (A.N.U. Press, Canberra).

LINDSAY, F.D., SCHEELAR, M.D. and TWARDY, A.G. (1973) - Soil survey for urban development. Ggoderma IO : 34-45.

LITTLE, I.D. and WARD, W.T. (1981) - Chemical and mineralogical trend in a chronosequence developed on alluvium in eastern Victoria, Australia. Geodg2ma 25 : 173-188.

LOVEDAY, J. (1974) - Aggregate Stability Chapter 9. I~ "Methods for Analysis of Irrigated Soils" ed. $. Loveday, C.A.B. Technical Communication, Number 54.

McCOWN, R.L., MURTHA, G.G. and SMITH, G.D. (1976) - Assessment of available water storage capacity of soils with restricted subsoil permeability. WaFd@~r R~ouwt£~ R~tch 12 : 1255-9.

MULLINS, J.A. (1981) - Estimation of the plant available water capacity of a soil profile. A~an ]o~ of $o~ Rg~g~L%c.h 19 : 197-207.. - 78 -

MURATA, U. (1975) - Estimation and simulation of rice" yields from climatic factors. Ag~cll2_FZ~tc~2.M~t£orology 15 : 117-31.

MURTHA, G.G. and REID, R. (1976) - Soils of the Townsville area in relation to.urban land use. C.S.I.R.O. Australian Division of Soils Di?isional Report No. II.

NORTHCOTE, K.A. and SKENE, D.J.M. (1972) - Australian soils with saline and sodic properties. C.S.I.R.O. Division of Soils, Soil Publication No. 27.

NORTHCOTE, K.H. (1971) - "A Factual Key for the Recognition of Australian Soils." 3rd edition (Rellim Technical Publications: Glenside, S.A.).

OLSON, G.W. (1973) - Soil Survey interpretation for engineering purposes. Food and Agriculture Organisation of the United Nations, Soils Bulletin No. 19.

PAINE, A.G.L. (1972) - Geology: Burdekin-Townsville region, Queensland. Resources Surveys Department of National Development, Australia.

P.C.A. (1962) - PCA Soil Primer. Portland Cement Association, Old Orchard Rd., Skokie, Illinois, USA. 52p.

PROBERT, M.E. (1977) - The Distribution of Sulphur and Carb0n-Nitrogen- Sulphur Relationships in some North Queensl~nd Soils. C.S.I.R.O. Australia, Division of Soils Technical Paper No. 31.

RAUPACH~ M. and TUCKER, B.M. (1959) - The field determination of soil reaction. 3OU2~u~ Of Zh~ A~~n I,~t~tuZz of Ag~/~ Sc~£n££ 25 : 129.

REID, R.E. (1978) - Phosphorus status of a Barratta soil of the Burdekin flood plain~ Agricultural Chemistry Branch Technical Memorandum 1/78.

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THOM, B.G. and CHAPPELL, $. (1975) - Holocene sea levels relative to Australia. S~Yt~ 6 : 90-3.

THOMSON, C.H. and BEC~MANN, G.G. (1982) - Gilgai in Australian Black Earths and some of its effects on plants. Tropical Agric~ure (Trinidad) 59 : 149-156.

THOMPSON, W.P. (1977) - Soils of the Lower Burdekin River - Elliot River area, North Queensland. Technical Report Agricultural Chemistry

Branch Queensland, Department of Primary Industries, No. I0. • .

THOMPSON, W.P., BAKER, D.E. and CANNON, M.G. (1981) - Soils of the Proserpine lowlands, North Queensland. Technical Report Agricultural ChemistrF Branch Queensland, Department of Primary Industries, No. 18. z

VAN WIJK, C. (1971) - Farm production and ?eturns - Soils. ~ "Report on extensi6n of Burdekin River irrigaZion project." Queensland Department of Primary Indhstries and Queensland Irrigation and Water Supply Commission,• Brisbane.

WALKER, P.H. (1963) - A reconnaissance of soils in the Kempsey district, N.S.W. C.S.I.R.O. Australian Soils and Land Use Series No. 44.

WYRWOLL, K.H. (1977) - Late Quaternary events in Western Australia. S£s#tcJ% 8 : 32-4.

YULE, D.F. and RITCHIE, J.T. (1980) - Soil shrinkage relationships of Texas vertisols. I. Small cores. Soil. Science Society of Amz~uican Iou2~ 44 : 1285-1291. - 80 -

APPENDIX 1

Vegetation - Common and Botanical Names

Species Referred to in Table 5.1:

Trz~ :

Beef wood " Grav//~ sZ~ Burdekin plum PIziogynium timorens£ Cabbage gum or Ghost gum E~ypZ~ pap~ Carbeen E. ~~ Cockatoo apple P~o~ ~£ya

Grey bloodwood or Long-fruited bloodwood ~y~Z~ ~o~a Grey ironbark 6. ~epanophy~ Pandanus P~~ Sp. Poplar g~ ~pZ~ ~ba Red-topped bloodwood E~ ~omop~o~ Tea-t~ee M~~ sp.

S~bs :

Broad leaf tea-t=ee M~~ v~flo~ ~alse sa~4alwood Er~op~ ~ch~ Grass t~ee X~ho~o~ joh~o~ Quinine bus~ P~os~g~ pub~c~

G~s~ :

Blue grasses Bo~o~oa and Dic~}~ spp. Brown so~gh~ Sorg~ ~~ Button ~rass ~ylo~~ ~~ Cane grass Op~oS megaphy~ ~linders ~rass Is~a S~. Giant spear grass H~opogon ~c~ Kang~oo grass Th~e~ ~~ Purple top chloris C~o~ b~b~ Spear ~rass H~opogon co~o~

Species of Sparse Occurrence:

Trzzs and Shrubs:

Bauhinia Lysip~4flam ca2Ao.ii Chinese apple Zizip~ m~a~u~t~o~% Batswing coral tree E~/]Z~n~I ug~pg2~O Corkwood AC~C~% bidmilfii Leichhardt tree ~C~1 0~£n~

Mimosa Ac~tc/~t f agUr~/~u~a Native ebony Ly~i~Im hookZzui - 81 -

Parkinsonia Pa2J~n~o~ aC/L~Z~Z~ Red siris Albizi~ loon Reid River box or Browns box ~CIL~J~Z~ b~ouf/~i~. Rubber vine C~pZo4Zag~ g~n~6£o~ W~itewood A~a h~g~ Willow wattle A~ S~~

G~S~:

~olden beard ~=ass C~sopogon f~x ~=ale= ~=ass Th~e~ q~v~v~ Love ~=asses E~gros~ spp. ~Mossman Rive~ ~ss Cen~ ec~~ Wild ~ice O~za spp. wi=e ~=ass A~~ spp.

Exotic grasses also occur, including guinea grass (Pan/cam m~x/m~m), buffel (Czn~ c~), sabi grass (U~o~oa mosambic~i~), para grass (E~t~c~ m~t~c~) and various species of couch grasses (Cynodon S~p. and Dig~ S~. ).

Although not grasses, sedges (Cyp£Au~ Spp.) are common in the wetter areas on a seasonal basis. - 82 -

APPENDIX 2

Relationships between Soil Profile Classes and Soil Series (Hubble and Thompson 1953)

Soil Hubble and Series qualifiers profile Thompson class ser~es ~

1 Use Lingilor i Dba Gaynor Clay loam (see Thompson 1977). i Dbb Gaynor Sandy loam to sandy clay loam, deep A horizon (see Thompson 1977). 2 Ugd Barratta Bleached light clay.

2 Use Barratta Light clay.

2 Ugf Barratta Medium heavy clay. 2 Ugg Barrafita Medium heavy clay. 2 Ugh Barratta and Medium heavy clay Yalinga L 2 Ugi - .. 2 Ugj -

• 2 Dbc Oakey Clay loam, deep A horizon.

2 Dbd Oakey Clay loam, deep A horizon. 2 Dbe Oakey Clay loam.

2 Dbf Oakey Sandy loam.

2 Dyb Oakey Clay loam.

2 Dyc Oakey Clay loam, gilgaied.

2 Dda Dowie Clay loam.

2 Ddb Dowie Clay loam. 2 Ddc - 2 Ddd - 4 Ucb Penwood Sand, pale A2 horizon. 4 Ucc Kinwood Sand, bleached A2 horizon. 4 Uce Mellawood Sand.

4 Gnb -

4 Dyd - 4 Dyj Mulgrave Sandy loam, colluvial not alluvial.

4 Dga Grendal Sandy loam, deep A horizon. 5 Dra Dalrymple Fine sandy clay loam (see Thompson 1977). 5 Dyc Ranly Sandy clay loam, A horizon often deep. 5 Dye Kyanoota Sandy clay loam. 6 Ucb Hylo Sand. 6 Uma Burdekin Fine sandy loam to fine sandy clay loam.

6 Umb -

6 Ufd - - 83 -

Soil Hubble and Series qualifiers profile Thompson class series*

6 Gna Farencer Fine sandy clay loam, here associated with Burdekin River, not local streams. 6 Gnb Clare Sandy loam, brown (and red-brown) subsoil

• variant. 6 Gnc Tootra Sandy clay loam, alkaline variant.

6 Gnd Burdekin and Fine sandy loam.

Elkin

6 Dra Lancer Sandy loam.

6 Drb Lancer Sandy clay loam. 6 Drc Lanona Sandy clay loam. 6 Dbb Glenalder Fine sandy clay loam, alkaline variant. 6 Dbc Glenalder Sandy clay loam, neutral variant. 6 Dbd Glenalder Sandy clay loam, alkaline variant. 6 Dbe Glenalder Sandy clay loam, alkaline variant with shallow A horizon. 6 Dya Tootra Sandy loam, deep A horizon.

6 Dyb Clare Sandy loam.

6 Dyc Tootra Sandy clay loam. 6 Dyd Tootra Sandy clay loam, shallow A horizon.

6 Dye Kelona Sandy loam. 6 Dyf Lanona Sandy clay loam, yellow subsoil variant. 6 Dyg Kelona Sandy clay loam, shallow A horizon.

6 Dyh -

* Includes those of Crack, B.J. and Clarke, R. (unpublished data).

The following sources were used to compile this table:

CRACK, B.J. and CLARKE, R. (unpublished data).

HUBBLE, G.D. and THOMPSON, C.H. (1953) - The soils and land use potential of the lower Burdekin Valley, North Queensland. C.S.I.R.O. Australia Soils and Land Use Series, No. i0.

HUBBLE, G.D. and THOMPSON, C.H. (unpublished data).

REEVE, R., HUBBLE, G.D. and THOMPSON, C.H. (1960) - The laboratory examin- ation of soils from the lower Burdekin Valley, North Queensland. C.S.I.R.O. Australia Division of Soils, Divisional Report No. 7/59.

~ THOMPSON, W.P. (1977) - Soils of the lower Burdekin River - Elliott River area, North Queensland. Queensland Department of Primary Industries, Agricultural Chemistry Branch, Technical Report No. i0. - 84 -

APPENDIX 3

Conventions used in the Description of the Morphology of Soil Profile Classe~ (Table 5.1)

(a) Horizon nomenclature is as per McDonald (1977).

(b The pH profiles are based on field determinations made at 5, 30, 60, 90, 120 and 150 cm depths.

(c Principal profile forms are listed in order of decreasing frequency of occurrence.

(d) Moist colours are those of Oyama and Takehara (1967) while colour nomenclature is that of R.C. McDonald (personal communication) based on the Value/Chroma rating system of Northcote (1979) and utilizing the following table:

Value/Chroma 2a = 4/1 - 4/2 to 6/1 - 6/2

Value/Chroma 2b = 5/3 - 5/4 to 6/3 - 6/4

Value/Chroma -.I 2a 2b 4 5 . Rating .

Hue

1OR dark red-grey red-brown red red

2.5YR dark grey-brown red-brown red red

5YR dark grey-brown brown red-brown red-brown

7.SYR dark grey-brown brown yellow-brown brown

10YR dark grey yellow-brown yellow brown 2.5Y dark grey yellow-grey yellow olive-brown

5Y dark grey yellow-grey yellow olive

(e) Self mulch:

Weak < 1 cm of poorly developed self mulch.

Moderate = 1-2 cm of discrete aggregates breaking to granular peds.

Strong > I-2 cm of discrete aggregates breaking to granular peds.

(f) Mottling:

Weak < 10%.

Moderate = 10-25.

Strong > 25%.

(g) Boundaries:

indicates clear or abrupt boundary.

indicates diffuse o~ gradual boundary. - 85 -

h) Gilgai:

Incipient < 5 cm vertical interval.

• Weak : 5-10 cm vertical interval.

Moderate = 10-30 cm vertical interval.

Strong > 30 cm vertical interval.

i) Structure:

As per Soil Survey Staff (1951).

Lenticular size categories defined as for prismatic.

j) Frequency of occurrence:

Frequently = on 30-90% of occasions.

Occasionally = on 10-30% of occasions.

(k) Vegetation:

Structural forms as per Specht (1970).

References

McDONALD, R.C. (1977) - Soil horizon nomenclature. Queensland Department of Primary Industries, Agricultural Chemistry Branch, Technical Memorandum 1/77.

NORTHCOTE, K.H. (1979) - "A Factual Key for the Recognition of Australian Soils." 4th ed. (Rellim Technical Publications : Glenside S.A.).

OYA~V~A, M. and TAKEHARA, H. (1967) - "Revised Standard Soil Colour Charts." (Fujihara Industry Co. Ltd. : Tokyo).

SOIL SURVEY STAFF (1951) - "Soil Survey Manual." United States Department of Agriculture Handbook 18. (U.S. Government Printing Office, Washington, D.C.).

SPECHT, R.L. (1970) - Vegetation. ~ "The Australian Environment." (Ed. G.W. Leeper) pp. 44-67 (C.S.I.R.O. in association with Melbourne University Press : Melbourne).

:. - 86 -

APPENDIX 4

1:25 000 Reference Area Mapping Unit Composition

~ ,, Map unit Dominant Associate Minor profile Area profile class profile class classes (ha)

2 Ugd 2 Ugd (90%) 2 Uge, 2 Dyc 64.6 2 Uge 2 Uge (80%) 2 Dyb, 2 Ugd 369.0 2 Ugf 2 Ugf (80%) 2 Ugg, 2 Ugd 93.0 2 Ugg 2 Ugg (80%) 2 Ugh, 2 Uge 2 Ugf 135.4 2 Ugh 2 Ugh (90%) 2 Ugg, 2 Uge 2 Ddb 282.9 2 Dbc 2 Dbc (75%) 2 Dbd, 2 Dyb 2 Dbe 12.7 2 Dbd 2 Dbd (75%) 2 Dbc 2 Dyb 2 Dbe 75.3 2 Dbe ~. 2 Dbe (70%) 2 Dyb 2 Dbc 2 Dda 14.6 2 Dyb 2 Dyb (80%) 2 Dbd, 2 Ddb 2 Uge, 2 Dda 402 5 2 Dda 2 Dda (75%) 2 Ddb 2 Dyb 2 uge 39 2 2 Ddb 2 Ddb (80%) 2 Dyb 2 Dda, 2 Uge 170 9 2 Dyc 2 Dyc (90%) .2 Ugd 2 Dyb 54 4 2 Ddc-2 Ugi 2 Ddc (60%) 2 Ugi (30%) 2 Ugh 2 Dyb 28 5 2 Uge-2 Ugd 2 Uge (50%) 2 Ugd (40%) 2 Dyb 2 Ugg 28.5 2 Uge-2 Ugh 2 Uge (60%) 2 Ugh (30%) 2 Ugg 55.7 2 Dbd-2 Uge 2 Dbd (50%) 2 Uge (30%) 2 Dyb 2 Dbc, 2 Ddb 8.2 2 Dyb-2 Uge 2 Dyb (55%) 2 Uge (30%) 2 Ddb 2 Ugd 41.1 2 Ddb-2 Uge 2 Ddb (60%) 2 Uge (30%) 2 Dda 2 Ugh 35.4 2 Ddb-2 Dyb 2 Ddb (50%) 2 Dyb (40%) 2 Dda 2 Uge 77.2 6 Dra 6 Dra (85%) 6 Drb 6 Dyb, 6 Dyg 113.3 6 Drb 6 Drb (80%) 6 Dyd 6 Dra, 6 Dyg 234.8 6 Drc 6 Drc (70%) 6 Dyf 6 Drb, 6 Dyg 113.9 6 Dya 6 Dya (85%) 6 Dyb 6 Dyg 134.2 6 Dyb 6 Dyb (80%) 6 Dya 6 Dyg 163.9 6 Dyc 6 Dyc (80%) 6 Dyb 6 Dyd, 6 Dyg 95.6 6 Dyd 6 Dyd (85%) 6 Drb 6 Dyc, 6 Dyg 146.8 6 Dye 6 Dye (70%) 6 Dya 6 Gnc, 6 Dyg 57.6 6 Dyf 6 Dyf (70%) 6 Drc 6 Dyd, 6 Dyg 179.1 6 Dyg 6 Dyg (80%) 6 Dyf 6 Dye, 6 Gnc 34.2 6 Dyh 6 Dyh (90%) 6 Ufd 8.2 6 Gnb 6 Gnb (80%) 6 Dya, 6 Dra 25.3 6 Gnc 6"Gnc (70%) 6 Dyf, 6 Dya, 2 Dyb 23.4 6 Ufd 6 Ufd (90%) 6 Dyh 4.4 6 Gnc-6 Dyd 6 Gnc (50%) 6 Dyd (35%) 6 Dyf, 2 Dyb 10.1 6 Gnc-6 Dyf 6 Gnc (50%) 6 Dyf (30%) 2 Dyb 14.6 6 Gnc-2 Dbd 6 Gnc (50%) 2 Dbd (25%) 6 Dyf, 2 Dyb 21.5 6 Gnc-2 Dyb 6 Gnc (50%) 2 Dyb (35%) 6 Dyf, 2 Ddb 94.9 6 Gnc-2 Ddb 6 Gnc (50%) 2 Ddb (30%) 2 Dyb, 6 Dyf 80.4 E E 82.3 : SP SP 116.5 - 87 -

APPENDIX 5

Morphological and Analytical Data for Representative Soil Profiles

Selected chemical and physical properties are summarised in Appendix 5(a). These are presented for 5 depths within each of the interpretive groups discussed in Section 6.

Appendix 5(b) gives detailed morphological and analytical data for representative soil profiles. These are presented in the same order as Table i.i (page 2). Notes relating to soil profile morphology correspond to those of Appendix 3 for (a), (d, except for names), (e), (i) and (k). All chemical data are presented on an (I05°C) oven dry basis except for pH and EC, acid extractable and bicarbonate extractable phosphorus, replaceable potassium and DTPA trace elements which are (40"C) air dry values. - 88 -

APPENDIX 5 (a) Summ~r~ by groups for ~ d~p~hs o/ ~or c~em6c~ ~nd phy86ca~ proper~68s

pH E.G, C1 Exchangeable % Clay R~ PAWC Total Total Total mS cm -~ % P K S Ca Mg Na K CEC % % % m. equiv, i00 g'~

Group A 0-i0 6.1 0.044 0.002 8.2 6.5 O.& 0.54 57.0 42.3 0.58 22.4 0.0~9 1.47 0.017 20-30 6.7 0.031 0.003 18.0 10.2 1.2 0.33 56.7 57.8 0.63 17.4 O.017 1.41 0.011 50-60 7.3 0,190 0.012 14.5 12.6 2.3 0.26 57.6 57.0 0.69 12.0 O.016 1.40 O.010 80-90 8.4 0.411 0.039 14.2 14.5 3.5 0.24 59.2 55.5 0.71 i0.i 0.019 1.44 0.012 140-150 8.6 0.504 0.051 9.8 11.5 3.8 0.26 63.0 41.7 0.79 0,037 1.79 0.011

Group B 0-i0 6.9 0.070 0,005 17.8 i0.I 0.6 0.49 65.2 54.7 0.52 22.4 0.020 1.34 0.013 20-30 7.5 0.063 0.002 18.7 11.3 1.4 0.27 63.7 57.2 0,61 17.5 0.015 1.30 0.008 50-60 7.9 0.198 0~016 16.3 13.2 3.1 0.28 63.8 56.0 0.70 12.1 0.014 1.31 0.008 80-90 8.3 0.386 0.038 15.1 13.8 4.5 0.28 63.5 56.3 0.79 10,3 0.01A 1.36 0.013 140-150 8.4 0.726 0.080 12.7 13.2 5.8 0.31 66.2 52.3 0.89 0.029 1.59 0.014

Group C 0-i0 6.1 0.031 0.002 2.7 3.3 0.4 0.34 79.0 17.4 0.69 22.5 0.031 1.53 0.012 20-30 7.1 0.147 0.017 7.1 i0.0 3.9 0.15 59.2 42.4 0.80 17.0 0.019 1.45 0,013 50-60 8.8 0.674 0.077 8.8 13.0 7.8 0.16 59.6 50.2 0.91 11.6 0.016 1.53 0.015 80-90 8.9 0.827 0.091 7.7 11.8 8.8 0.21 61.2 42~.6 0.90 9.0 0.023 1.71 0.007 140-150 8.8 0.602 0.064 6.4 10.0 8.4 0.22 68.0 38.4 0.89 0.028 1.90 0.007

Group D 0-i0 6.6 0.040 0.002 3.0 4.0 0.8 O.&4 63.0 22.8 0.56 22.5 0.028 1.38 0,012 20-30 8~8 0,361 0°034 8.2 9.8 5.9 0.13 61.8 41.0 0.79 17.1 0.O18 1.37 0.016 50-60 9.2 0.942 0,102 6.9 9.3 9.4 0.14 62.0 42.8 0.85 11.5 0.017 1.47 0,019 80-90 9.4 0.988 0.106 6.2 9.1 9.4 0.18 64.8 38.2 0.86 9.9 0.023 1.66 0.009 140-150 9.1 0.707 0.075 4.6 7.3 8.4 0.19 66.6 30.8 0.86 0.029 2.02 0.008

Group E 0-10 6.2 0.022 0.001 4.1 2.0 0.i 0.40 85.6 11.8 0.64 22.6 0.047 2.39 0.010 20-30 6.6 0.024 0.001 7.6 4.7 0.3 0.31 67.6 26.0 0.62 16.7 0.038 2.25 0.007 50-60 7.6 0.040 0,001 10.4 6.3 0.6 0.28 58.0 28.8 0.62 i0.4 0.048 2.33 0.007 80-90 8.3 0.054 0.001 7.7 4.6 0.5 0.29 86.2 15.2 0.54 6.7 0.044 2.48 0°003 140-150 8.3 0°040 0.002 9.4 5.0 0.9 0.16 93.2 16.8 0.63 0.038 2.35 0.002

Group F 0-10 6.1 0.018 0.001 2.1 0.8 0.i 0.30 87.2 7.6 0.58 22.6 0.025 1.74 0.008 " 20-30 6.3 0.010 0.O01 2.0 1.0 0.i 0.19 47.0 12.0 0.66 16.0 0.018 1.89 0.006 50-60 6.6 0.013 0.003 6.5 4.1 0.3 0.34 32.4 50.8 0.38 11o8 0.038 1.84 0.007 80-90 6.7 0.010 0.008 5.9 3.8 0.4 0.29 32.6 44.2 0,45 9.3 0.033 1.40 0.004 140-150 7.3 0.021 0.001 7.0 4.4 0.6 0.28 45.6 30.0 0.64 0.025 2.04 0,004

Group G 0-10 6.0 0.024 0,002 3~7 1.9 0.i 0,41 67.8 16,2 0.59 22.6 0.040 1.98 0.013 20-30 6.3 0.020 0.001 5.0 3.0 0.2 0,27 44.8 31.6 0.59 16.6 0.023 2.07 0.009 50-60 7.0 0.034 0.002 8.9 6.0 0.6 0.38 39.3 52.8 0.55 ll.5 0.020 2.03 0.007 80-90 7.9 0.080 0.002 10.8 7.4 1.0 0.40 46.0 50.8 0.65 9.5 0.025 2.10 0.007 140-150 8.4 0.164 0.016 I0.i 7.5 1.3 0.30 61o8 31.6 0.71 0.034 2.24 0.006

B£carb O~g Total C/N C:N:S Cu Zn Mn Fe P C N ratio ppm ppm ppm ppm ppm ~ ~

Group A 0-i0 8 i.i 0.08 14 133:10:2.1 2.3 i.I 81 93

Group B 0-i0 A 0.9 0.07 15 145:10:2.0 2.2 0.8 55 88

Group C 0-i0 7 1.0 0.08 14 135:10:i.6 1.6 1.0 62 86

Group D 0-i0 7 0.9 0,07 14 137:10:1.8 i.l 0.6 54 73

Group E 0-I0 44 0.9 0.05 19 167:10:1.9 0.7 2.4 54 91

Group F 0-i0 13 0.7 0.04 16 189:10:2.2 0.7 Z.4 64 59

Group G 0-i0 18 1.0 0.06 17 154:10:2.0 1.0 2.4 61 66 - 89 -

APPENDIX 5(b)

Morphological and Analytical Data for Representative Soil Profiles 90a

90b

91a

91b

92a

92b

93a

93b

94a

94b

95a

95b

96a

96b

97a

97b

98a

98b

99a

99b

100a

100b

101a

101b

102

103a

103b

104

105a

105b

106a

106b

107a

107b

108a

108b

109a

109b 110a

110b

111a

111b

112a

112b

113

- 114 -

APPENDIX 6

Classification of Profiles Sampled for Detailed Analysis

t Soil Site P.P.F. Great Soil Soil Taxonomy Unified Soil profile No. (North- Group subgroup (Soil Classification class cote (Stace Survey Staff (PCA 1962) 1979) £Z ~ 1968) 1975) A Horizon B Horizon

2 Ugd a* 3 Ug3.2 Grey clay Entic Chromustert CH CH

2 Ugd a 7 Ug3.3 Brown clay Entic Chromustert CH CH

2 Dyc a 24 Dy3.33 Solodized Udic Paleustalf CL CH solonetz

2 Dyc b 25 Dy3.33 Solodized Aquic Haplustalf CL CH solonetz or solodic 2 Uge a 5 Ug5.29 Grey clay Entic Chromustert CH CH 2 Uge a 9 Ug5.29 Grey clay Entic Chromustert CH CH 2 Uge b* I~ Ug3.1 None Entic Chromustert CH CH appropriate 2 Uge a 47 Ug3.2 Grey clay Entic Chromustert CH CH

2 Ugg a 17 Ug3.2 Grey clay Entlc Chromustert CH CH

2 Ugg a 29 Ug5.29 Grey clay Entic Chromustert CH CH

2 Ugh a 38 Ug5.29 Grey clay Entic Chromustert CH CH

2 Ugh b 39 UgS.16 Black earth Typic Chromustert CH CH

2 Ugh a 40 Ug5.29 Grey clay Entic Chromustert CH CH 2 Ugh a 42 Ug5.34 Brown clay Entic Chro~ustert CH CH 2 Ddc b 44 Dd2.33 Solodized Mollic Natrustalf CL CH or MH solonetz or solodic 2 Ugi a 43 Ug5.34 Brown clay Entic Chromustert CH CH

2 Dbd 12 Dbl.43 Solodic Typic Natrustalf CL CH or MH 2 Dyb 16 Dy3.43 Solodized Typic Natrustalf CL CH or MH solonetz 2 Dyb 21 Ddl.33 Solodized Typic Natrustalf CL CH or MH solonetz 2 Dyb 31 Dy2.33 Solodic Typic Natrustalf ML-CL CH or MH 2 Dyb 45 Dbl.33 Solodic Mollic Natrustalf CL CH or MH ~ Dda 15 Ddl.43 Solodized Typic Natrustalf CL CH or MH solonetz 2 Ddb 19 Dd2.33 Solodic Typic Natrustalf CL MH 2 Ddb 22 Ddl.33 Solodized Typic Natrustalf CL CH or MH solonetz 2 Ddb 27 Db2.33 Solodized Typic Natrustalf CL CH or MH solonetz

• , 2 Ddb 53 Dbl.43 $olodized Typic Natrustalf CL CH or MH solonetz

4 Gnb 20 Gn3.41 Red Oxic Paleustalf SM SC podzolic - 115 -

Soil Site P.P.F. t Great Soil Soil Taxonomy Unified Soil profile No. (North- Group subgrou p (Soil Classification class cote (Stace Survey Staff "(PCA 1962) 1979) g~ ~ 1968) 1975) A Horizon B Horizon

6 Umb 32 Um6.31 Prairie Udic Argiustoll ML CL soil

6 Dbc 35 Db2.32 Grey-brown Udic Paleustalf ML CL podzolic soil

6 Dbd 33 Db2.43 Red-brown Udic Haplustalf ML MH earth

6 Dbd 34 Db2.33 Red-brown Udic Haplustalf ML MH earth 6 Dbd 36 Db2.43 Red-brown Udic Paleustalf ML MH earth 6 Dbe 37 Dbl.33 Red-brown Typic Paleustalf ML-CL MH earth

6 Dbe 63 Dbl.33 Red-brown Udic Paleustalf ML MH earth

6 Gnb 23 Gn3.15 Red Arenic Paleustalf SM SC podzolic

6 Gnc 60 Gn3.83 None Udic Haplustalf ML MH appropriate

6 Dra 50 Dr3.32 Red Udic Paleustalf SM MH podzolic 6 Drb 2 Dr3.42 Red Udic Paleustalf ML-CL MH podzolic

6 Drb 52 Dr3.32 Red Udic Paleustalf CL MH podzolic 6 Dyd 49 Dy3.42 Yellow Udic Paleustalf SM MH podzolic

6 Dyd 59 Dy3.42 Yellow Udic Paleustalf SM MH podzolic

6 Drc 1 Dr3.43 Solodic Udic Paleustalf CL MH 6 Drc 28 Dr3.33 Solodic Udic Paleustalf CL MH 6 Dya 26 Dy3.42 Yellow Udic Haplustalf SM SC or MH podzolic 6 Dyf II Dy3.43 Solodic Udic Paleustalf CL MH 6 Dyf 13 Dy3.43 Solodic Udic Paleustalf CL MH 6 Dyf 14 Dy3.43 Solodic Udic Paleustalf CL MH 6 Dyg 58 Dy3.42 Solodized Aquic Natrustalf SC MH solonetz

* a - Mound.profile of gilgaied area.

• b - Depression profile of gilgaied 8mea. t Principal Profile Form. - 116 -

References

NORTHCOTE, K.H. (1979) - "A Factual Key for the Recognition of Australian Soils." 3rd ed. (Rellim Technical Publications : Glenside, S.A.).

P.C.A. (1962) - PCA soil primer. Portland Cement Association, Old Orchard Rd., Skokie, Illinois, USA. 52p.

SSIL SURVEY STAFF (1975) - "Soil Taxonomy: A basic system of soil classification for making and interpreting soil surveys." United States Department of Agriculture Handbook No. 436.

STACE, H.C.T., HUBBLE~ G.D., BREWER, R., NORTHCOTE, K.H., SLEEMAN, J.R., M]/LCAHY, M.J. and HALLSWORTH, E.G. (1968) - "A Handbook of Australian Soils." (Rellim Technical Publications : Glenside, S.A.). - 117 -

APPENDIX 7

Land Capability Classification Schemes

LAND CLASSES

The limiting factors set out in Table 1 have been integrated to allocate mapping units to a modified version of the land classes £efined by the United States Bureau of Reclamation (1953). Because paddy rice has different requirements from those of other irrigated crops, a set of crop specific land classes has been developed for it and Table 2 sets out the limiting factors used.

Land Classes For Crops Other Than Ric~

CLASS 1 - ARABLE

Lands that are highly suitable for irrigation farming, being capable of producing sustained and relatively high yields of a wide range of climatically adapted crops at reasonable cost. They are smooth lying with gentle slopes. The soils are deep and of medium to fairly fine texture with mellow, open structure allowing easy penetration of roots, air and water and having free drainage yet good availble moisture capacity. These soils are free from harmful accumulations of soluble salts or can be readily reclaimed. Both soil and topographic conditions are such that no specific farm drainage requirements are anticipated, minimum erosion will result from irrigation and land development can be accomplished at relatively low cost.

CLASS 2 - ARABLE

Lands of moderate suitability for irrigation, being lower than Class 1 in productive capacity. They are not as desirable nor of such high value as lands of Class 1 because of certain limitations. They may have a lower available moisture capacity as indicated by coarse texture or limited soil depth; they may be only slowly permeable to water because of clay layers in the subsoil; or they also may be moderately saline which may limit productivity or involve moderate costs of leaching. Topographic limitations include uneven surface requiring moderate costs for levelling, short slopes requiring shorter length of runs, or steeper slopes necessitating special care and greater costs to irrigate and prevent erosion. Farm drainage may be required at a moderate cost or loose rock or woody vegetation may have to be removed from the surface. Any one of the limitations may be sufficient to reduce lands from Class 1 to Class 2 but frequently a combination of two or more of them is operating.

CLASS 3 - ARABLE

Lands that are suitable for irrigation development but are of restricted suitability because of greater limitations in soil, topographic, or drainage characteristics than described for Class 2 lands. They may have good topography, but because inferior soils have restricted adaptability, require larger amounts of irrigation water or special irrigation practices and demand greater fertilization or more intensive soil improvement practices. They may have uneven topography, moderate to high concentration of salts or restricted drainage. These lands are susceptible to correction but only at relatively high costs. .Generally, greater risk may be involved in farming Class 3 lands than better classes of land, but under proper management they are expected to have adequate payment capacity. - 118 -

CLASS 4 - LIMITED ARABLE OR S~ECIAL USE

These are lands that have an excessive specific limitation (or limitations) which is able to be corrected at high cost or lands that. have limitations which ape not able to be corrected and are thus restricted to pasture, orchard or other relatively permanent crops. The limitation may be inadequate drainage, excessive salt content requiring extensive leaching, unfavourable position allowing periodic flooding or making water distribution and removal very difficult, rough topography, excessive quant- ities of loose rock on the surface or in the plough zone. On these lands special economic and agronomic and/or engineering studies are required to show they are capable of sustained production and capable of supporting a farm family and meeting water charges if operated in units of adequate size or in association with better lands.

CLASS 5 - NON-ARABLE

Lands in this class are non-arable under existing conditions. They have specific soil limitations such as being excessively steep, shallow, rocky, rough or badly eroded or have very high salinity.

Land Classes For Ric~

CLASS I

Lands that are highly suitable for rice production being capable of producing sustained high yields even under double cropping. Slopes allow bay widths of 50 m or more but are sufficient to provide within- bay drainage. Microrelief is negligible. Soils are impermeable and uniform. The risk of flooding is low.

CLASS 2

Lands that are moderately suitable for production being capable of producing high yields. They are less attractive for rice production than Class ~ lands for one (or a combination) of the following reasons: microrelief may be present, increasing levelling costs and soil variability; slopes may be more variable; soils may be more permeable and variable; or the risk of flooding may be higher.

CLASS 3

Lands that are suitable for rice production but are of restricted suitability. They are not as productive as Class 2 lands because they require large applications of nutrients other than nitrogen; and/or because slopes are above or below optimum; and/or because soils may be more permeable; and/or because microrelief is more intense; and/or because the risk of flooding may be high.

CLASS 4

Lands where rice production is restricted because soil variability is such that bay design is extremely difficult or soil permeability is apparently high, increasing crop water use and raising the possibility that water tables could rise into the crop root zone under sustained cropping.

CLASS 5

Lands in this class are not suitable for rice production under existing conditions. Slopes are too high to allow adequate bay widths and/or soil permeability is apparently such that water use would be unacceptably high. - 119 -

SABLE 1 ,L~zv~ c:~=b~:~:y 2~ass:f~cav~ fgr J~uem 9uz'dgk~n S~:~ ~cnk

L~m~t~n 8 De~ree of [~m~tat~on Oapab~ll~y class Subclass fac~o¢ (~ ~ole ~m~n6 ~ymbo~ ~actor)

Effective ~ot! >i00 cm i dl depth 60-[00 2 d2 45-60 3 d3 25-~5 4 d4 <25 5 d5

So~l physical 'i. B hortzon or sub-so~l depth. Depth to B hotlzon wtth dry factors affectzng extremely hard conststence. plant growth and >45 c~ 1 pDl manaBem~nt 20-A5 2 pb2 iO-~0 3 pb3

2. Surface :rust. Surface sozls likely to set hard ~f overworked. 2 pc2 Surface soils set hard. 3 pc3

]. Distribution of so~l profile classes. Soil d£str£button ts such that 2 or more different soil proflie classes occur within a 300 m traverse. So~l profile classes are dtfferen~ such that markedly different inputs are required: For specific crops 3 pd] For any crop 4 pd4

4. reKturs of surface so,is. Sands to sandy [oams to:

&5-60 cm 2 pt2 60-90 3 pt3 >go 4 pt~

Soll salinzty or Electrical conduc~iv[ty of 1.5 suspension at 25°C ~s greater than sod~city I mS =m "~ a~:

30-90 cm 3 ss3 <30 4 sa~

Exchangeable sodium percentaBe greater than 15

40-90 :m 2 so2 20-40 3 ~o3 <20 ~ so4

Toposraphy Slopes 0.i-0.5% i tl 0.5-1.0 2 t2 1.0-3.0 3 t3 3.0-6.0 ~ ~4 6.0-8.0 5 t5

Rockiness and Tillage restrlc~ed - stone plcklng required. 3 r3 stoniness Tilla~e d~fftcult - stone pickzng requzred. A r4 T~lla~e tmposslble. 5 r5

Microrelief Vertical Interval of g~lgai: 60 ~ g~

Wetness Requires accura=e levellin 8 and storm drains. 2 w2 Requires permanen~ drainage. 3 w3

Susceptiblizty to TO reduce erosion to an acceptable level, requzres: water erosion Simple prac t~ces. 2 e2 Intensive practices. 3 e3 Pasture phase. A e4

Floodin s Areas subject to major r%ver overbank flood~n~ less often than 1 tn i0 years. 2 f2

A:eas subject to iota[ ftoodin~ ~"~ore often than i in i0 years. 3 f3 - 120 -

TABLE 2 Lm~d c~b~Z~C~ c~ass~f~caccon for r~ce o~ :A~ ,Co~ Burdek~n Ce/c ~nk

Lim~tzng Degree of !£m~atzon Capability class Subclass ~actor (i~ sole l~m~tlng symbol ~actor)

Topography 0.I to 0.3% slope - uniform I tl 0.1 to 0.3% slope - variable 2 t2 <0.1 oF 0.3 to 0.5% slope - varlable 3 t3 0.5 to 0.75%-slope - uniform ~ t4 >0.75% slope or 0.5 to 0.75% slope - variable 5 t5

Microrelief Vertical interval of S~Igai 60 cm ~ S~

Floodin S Areas sub3ect to r~ver overbank floodln S less often than i in lO years. 1 fl Areas sub~eit to local floodin S more often than 1 in I0 years but less 2 f2 often ~han I in 5 years. Areas subject to local floodins more often than I in 5 years. 3 fe

Soll fertility Areas requi~Ing n~zrosen plus less ~han 20 k S P ha -~ per crop. 1 nl Areas requzrln~ nitrogen ~lus more ~han 20 k S P ha -~ per crop or 3 n3 other nutrients.

Proflle Duplex soils with A horlzons <20 cm deep, extremely hard upper B ~orizons per~eabllit 7 and field textures in the clay range from the base of the A horizon to >150 cm. Profile s~ron$1y alkaline and/or ESP >15 by 60 cm. 1 pl Crackln 8 clay so~!s with alkaline soil teactlon trend and/or ~SP at 2 p2 some point in tlle profile > 15 and textures in the clay fanes extendin~ to >i50 im. Duplex soils with A horizons >20 :m deep, extremely hard upper B horizons and textures in the clay tense from the base of the A horizon to >!50 cm. Alkaline soll reaction ~rend asd/or ESP at some point in the profile >15. 3 p3 AS for p3 but upper B horizons not extremely hard. 4 p~ All gradatlonal, uniform and duplex soils wi~h aczd and neutral soll 5 p5 trends with ~SP <15 throushout profile and/or with some material wi~h texture coarser than sandy clay between AO and 150 cm.

Soil salinity Electrical conductivzty of 1:5 Extract at 25°C is Stealer them 1 ~S im "~ a~; i0 ~o 30 cm 4 sa4

Distribution of Distribution of soll proflle classes is such ~ha~ when 2 or more soil soll profile profile classes occur w~thln a 300 m traverse: Classes Soil profile classes are of slml[ar suitability for r~ce. 2 pd2 Soil profile classes are all suitable for rice but are O~ d ~fferent 3 pd3 sultabili=ies. One or more ~oli profile classes is not su~=able for r~ce. 4 pdA

Reference :

United States Deparrm~n¢ of the Interior, Sureau of Reclamation (1953) - Manual. Volume 5, part 2. LaJ~d classlf%cation handbook,