SOILS OF DENIBOOTA

IRRIGATION DISTRICT, N.S.W.

SOILS AND LAND USE SERIES No. 5

DIVISION OF SOILS

COMMONWEALTH SCIENTIFIC AND

INDUSTRIAL RESEARCH ORGANIZATION

MELBOURNE 1952

Soils of Deniboota Irrigation District and their Classification for Irrigation

By E. J. Johnston

Soils and Land Use Series No. 5

DIVISION OF SOILS

Commonwealth Scientific and Industrial Research Organization, Australia

Melbourne 1952 . CONTENTS

Page Summary 5 I. Introduction 5 II. Agricultural and Pastoral History 6 III. Climate 7 IV. Physiography 7

v. The Soils 8 VI. Acknowledgments 37 VII. References 38 VIII. Appendix I. Glossary of Botanical Names of Flora in the Deniboota Irrigation District 39

SOILS OF DENIBOOTA IRRIGATION DISTRICT

AND THEIR CLASSIFICATION FOR IRRIGATION

SUMMARY

A detailed soil survey of the Deniboota Irrigation District revealed that the area was composed of 50 per cent. heavy plain soils of doubtful suitability for the growing of pas­ tures and crops under irrigation and 8.8 per cent. of soils considered definitely unsuitable due to their being too high to be watered from the channels or too broken by gullies and creeks to allow for economic watering. There is 23.4 pE,r cent. of the area considered good irrigation soil for ucerne, summer and winter pastures, and irrigated s~r fodder crops. The remaining 17.8 i:er cent. is considered suitable for pas­ tures and crops but not economically suitabl3 for the growing of lucerne for hay. Most of the good irrigation soils are confined to the southern portion of the district, the moderate soils to the northern part, while the doubtful irrigation soils comprise the central half of the district. These latter soils are, at present, considered to be of doubtful suitability for irrigated crops (except rice) and pastures owing to the hard~setting surface soil, the stiff, imperm­ eable, and intractable clay subsoil, and the high salt content of .the soil.

It is hoped that further research into irrigation techniques and cultural practices may reveal a method by which these soils can be converted into an economic asset in the irrigation s~ere.

I. INTRODUCTION

The Deniboota Provisional Domestic and Stock Water Supply and Irrigation District was constituted on November 16, 1938 and proclaimed in the New South Wales Government Gazette No. 181, December 16, 1938.

The district comprises an area of 303,064 acres of land situated in the counties of Townsend and Cadell. It is bounded on the north by the Wakool River and Colligen and 6

Yallakool Creeks, and on the north-west by the Porthole and Thule Creeks. The boundaries of the irrigation district taper from Deniliquin in the east and Thule Creek in the west to a point approximately five miles west of the village of Womboota.

The district is to be served with water by the Mulwala Canal, which is being extended across the Edward River and Aljoe's Creek by the construction of the Lawson syphon two miles south-east of Deniliquin.

The irrigation district is made up of 147 properties to which have been allocated 23,935 water rights.* The size of the holdings is variable, ranging from 50 to 16,460 acres with an average area of 2,062 acres. The larger holdings are in the northern portion. These figures give a false impression of the actual land use tenure of the area as many properties are run as a family syndicate built up of two or more holdings. Other very small holdings are leased to the owner of a larger adjoining holding and some are used to agist stock awaiting sale in Deniliquin. Other small holdings represent only that portion of a much larger holding, the greater portion of which is outside the boundaries of the irrigation district and can­ not be irrigated.

A reconnaissance soil survey of the funiboota Irrigation District was carried out by the Division of Soils, Council for Scientific and Industrial Research, in 1942 (Smith and John­ ston 1942). The detailed soil survey here reported was commenced in October 1946 and completed in November 1948. II. AGRICULTURAL AND PASTORAL HISTORY

Before 1925 the majority of the area was used for the grazing of sheep for wool and for the fattening of beef cattla. The size of holdings varied from 4,000 to 15,000 acres when used for these purposes. In the south of the area a consider­ able area was sown to wheat each year on smaller properties around Bunnaloo and Womboota. With the construction of the Echuca-Balranald railway by the Victorian Railways, in 1925, the district was provided with the transport facilities nec­ essary for closer settlement.

The ruling high prices for agricult':ll'al products led to a * A water right is one acre-foot of water :p3r annum. 7 migration of wheat farmers from Victoria, who bought land along the railway, but the uncertain climate coupled with rather unsuitable soils caused only mediocre success to be obtained from wheat growing. The economic depression of 1929 forced some farmers to surrender their holdings and the remainder returned to sheep grazing. The small size of the holdings lead to overstocking in some cases, followed by wind removal of top soil and loss of native grasses. The effects of this treatrrent are still very evident in some holdings in the district. Population trends over this period can be gauged from the census records for Murray Shire, which embraces most of the Deniboota Irrigation District. These records show that the population was 3,130 in 1933 and 1,937 in 1947.

At the present time wheat growing is mainly confined to the soils about Womboota and Bunnaloo proven suitable for it and receiving a 15-inch annual rainfall. The chief industry is still wool production, one sheep being grazed on approxim­ ately three acres of natural pasture. Some cattle are grazed, mainly along the creek frontages where swamps and rough scrub make the land unsuitable for sheep.*

III. CLIMATE

The climate of the Deniboota Irrigation District has been fully covered by Smith (1943, 1945) and will be only briefly dealt with here. The climate is warm temperate with hot, dry s1.lll1Irers and only few winter frosts. The average annual rain­ fall at Deniliquin is 15.85 inches and 15.55 inches at Wom­ boota. There is a decrease in rainfall in the western portion of the area, only 13 .07 inches being recorded at Wakool. Approximately 60 ·per cent. of the annual rainfall falls during the winter months (April-September) and 40 per cent. occurs, mainly as summer thunderstorms, during the p:!riod October to March. This rainfall is unreliable and the use of irrigation water is essential for the reliable growth of crops and pastures.

IV. PHYSIOGRAPHY

The area is an even plain with a gentle fall from east to west. The northern and north-western portion is either * Departrrent of Lands, Sydney, kindly supplied details on land settlenent. 8 bounded or dissected by several semi-permanent watercourses such as the Colligen, Yallakool, Thule, and Porthole Creeks and the Wakool River. There are also several seasonal gullies or creeks, the chief of which is the Cochran-Yarrein Creek. The plains adjoining these watercourses have been subjected to periodical flooding and are naturally densely timbered. The central area consists of almost treeless plains with no perm­ anent watercourses. Certain low areas in the plain are liable to inundation by surface run-off and form timbered semi­ swamps. There are, however, many non-functional or dry stream-­ lines traversing the plains in a general east-to-west direc­ tion. These old streams belong to a previous era and have no relation to .the present permanent or seasonal watercourses. They are flanked by levees that form low ridges across the plains. The soils of these ridges are lighter than those of the surrounding plains and are usually lightly timbered. In the southern area these-non-functional streamlines form a net­ work and only small treeless areas of plain occur. The largest of these streamlines is Green Gully, which is located between Womboota and Thule Creek. Most of the others are well defined, but some remain as scarcely distinguishable shallow, linear depressions in the plain.

It will be shown that the soils of the area follow a pattern that is closely related to these non-functional streamlines and to the permanent watercourses. The outstanding topograph­ ical feature of the area is the presence of occasional sand­ hills, which may reach a height of 50 feet above the plain. They are usually found close to Green Gully.

V. THE SOILS (a) Soil Classification The soils of the Deniboota Irrigation District can be placed in six broad groups:

(i) Red-brown Earths.- Brown loam or sandy loam soils carrying timber. They occur in the plains in the north as low timbered ridges associated with non-functional stream­ lines and comprise most of the southern portion of the area.

(ii) Grey Soils Subject to Inundation.- Heavy clay soils which have been periodically inundated either by flood waters or rainfall run-off. They are usually heavily timbered and 9 display varying degrees of surrace distortion. This is lmown as gilgai formation or crabholiness. * (iii) Grey and Brown Soils of the Treeless Plains.- These_ are heavy clay soils of the open, level, almost treeless plains. Varying degrees of crabholiness are displayed by the different soil types.

(iv) Soils of the Sandhills.- Brown or dull brown deep sands~

(v) Soil Complexes.- These a~e mixed groups of varied miscellaneous soils that cannot be mapped as individual types. They are associated with defunct or seasonal streams .

. (vi) Soils of the Dry Stream Beds.- These soils occupy the beds of streams that have been non-functional for a great many years. They are variable, but usually sandy. Surface· colour ranges from brown -to grey. (b) Characteristics of Soil Types

(i) Red-brown Earths.- Thi.s group of soils embraces the following soil series in which there are one or more soil types:

(1) Purdanima series (Purdanima sand, Purdanima sandy loam). (2) Deniboota series (Deniboota ·sandy loam, Deniboota loam). (3) Bunnaloo series (Bunnaloo loam). (4) Womboota series (Womboota loam). (5) Wongal series (Wongal clay-loam).

The Purdanima and Deniboota soil series are found in close association with each other and occur as bands or strips across the area from east .to west in the central and northern *Gilgai formation refers to a contortion of the land sur- f ace into a series of "bumps II and "hollows 11 • The top of the mound is usually cracked and crumbly and so is termed the "puff". The depression or hollow is termed the "crabhole" due to the frequent presence of a small hole in the bottom of the depression. The smooth surface between the "puff" and· 11 crabhole II is termed the II shelf". 10 area. The Bunnaloo, Womboota, and Wongal soil series occur in association and cover most of the southern area.

(1) Purdanima soil series consists of light, sandy soils with a usually strongly cemented hardpan at a depth of 18 inches to 2 feet. This hardpan may extend to a depth of several feet and is of a hardness varying from slightly cemented to that of rock. In the latter case it is absolut­ ely impenetrable by the soil auger and even turned the point of the pick when pit examinations were being made. Beneath this hardpan are found coarse sandy materials. Purdanima sand has a surfacel consisting of 18 to 24 inches of brown sand, whilst Purdanima sandy loam has 15 to 18 inches of brown sandy loam, above the hardpan. There is usually very little clay in these soil types and, where present, it occurs as a thin layer of sandy clay ~diately above the .cemmted hardpan.

(2) The Deniboota soil series also consists of light soils though not as sandy as the Purdanima series and there is a complete absence of hardpan. Deniboota sandy loam has 10 or 12 inches of sandy loam · surfai e. Approximately half this surface soil (from Oto 6 inches) is brown in colour, whilst the remainder (from 6 to 12 inches) is a light brown colour. The subsoil 2 is a reddish brown crumbly clay 3 going to a dark brown clay which contains some limestone rubble. Below 24 inches the deep subsoil4 becomes progressively lighter and mottled in colour, the chief colours being grey, yellow­ brown, and black, decreasing in that order. The texture of the deep subsoil is usually a fine sandy loam by 48 inches and goes to a -sandy loam· or sand at some greater depth.

1 "Surface soil" refers to that portion of the soil above the clay pan. 2 "Subsoil" here refers to the clay pan, which is usually the layer or horizon in the soil that is darkest in col~ur, and contains the majority of the lime present. 3 A soil may be referred to as "crumbly" if it breaks up easily into lumps of one half inch or less when dug with a pick. 4 11 Deep subsoil" is an arbitrary term referring to the soil below 24 inches to a depth of 7 to 10 feet; i.e. maximum depth of examination. 11

Deniboota loam has a shallow surface of three or four inches of brown loam. The subsoil is a r~ddish brown nutty clay. Limestone rubble occurs at depths of approximately 15 to 18 inches. There is frequently present, at depths of 21 inches or more, a trace of very fine crystalline gypsum in mycel ial form. This gives a thread-like appearance through the soil as viewed on the side of a pit. The deep subsoil is yellow, grey, and brown mottled and becorres progressively lighter with depth. It is usually a fine sandy clay by 36 inches, becoming more sandy. At depths of 54 inches and below there is frequently a grey mottled silty clay in which l arge crystals of gypsum are found. The light profile phase of Deniboota loam has a slightly deeper surface (7 to 8 inches), a somewhat more crumbly clay in the subsoil,and a l ighter deep subsoil. This latter is usual ly a fine sandy clay by 24 inches. The Deniboota series is confined to the central and northern area.

(3) Bunnaloo loam is a soil occurring on low rises alongside the old streamlines in the southern area (Plate 3, Fig.2). This soil type has 6 inches of surface consisting of 3 inches of brown loam over 3 inches of light brown l oam. Beneath this the subsoil is a dark red-brown crumbl y clay which becomes a dark brown by 12 to 15 inches, where limestone rubble occurs.

Below 21 inches the colour becomes yellow-grey with brown mottling and the texture lightens to a fine sandy clay by 30 inches, becoming lighter with depth. As in the Deniboota loam, there is frequently a grey mottled clay in the deep subsoil. This has been termed the "heavy subsoil phase" of Bunnaloo loam. This clay occurs at any depth from 33 inches downwards and be comes heavier with depth. Neither 1~ nor gypsum occurs in this layer of soil.

(4) Womboota loam occurs in the same areas as Bunnaloo loam, as brown plains further back from the old streamlines (Plate 4). This soil type is somewhat similar to the Finley loam of the adjacent Berriquin Irrigation District (Johnston 1949) and to the light profile phase of Moira loam of the Murray Valley Irrigation Area (Butler 1942). There are 4 to 5 inches of brown loam surface soil, ·the bottom inch of which is usually light brown in colour. The clay subsoil is a reddish brown colour and not so crumbly as is the subsoil of Bunnaloo loam, the clay fragnEnts being larger and harder. 12

Limestone rubble apJ:Bars at 12 to 18 inches and below 24 inches the subsoil becomes grey and mottled in colour and is usually a light clay by 48 inches. There is a heavy profile phase of Womboota loam, which remains a heavy clay to depth.

( 5) Wong al clay loam is a brown plain soil marginal between the Womboota loam and the soils of the creek frontages. It is typically afforested with dense black box and the surf~ce shows some tendency to gilgai formation. The puff is fairly well developed, but the crabhole is only slightly develope·d into scarcely detectable depressions. The surface is a brown clay-loam, usually not more than 2 inches thick. The subsoil is a crumbly clay, which is dark reddish-brown mottled with grey, yellow, and black. Lime ap}:Bars early as limestone rubble at 6 to 8 inches. On the surface and in the upper layers of the soil are found small round black and brown iron concretions, known as "buckshot". At 24 inches the deep sub­ soil becomes a grey mottled clay.

(ii) Grey Soils Subject to Inundation.- These soils have all been influenced by varying degrees of flooding in the past. Levee banks along the creeks now protect much country previously flooded and the control of the river systems by a series of locks and weirs also has reduced the risk of inundation at the present time. The following soils belong to this group: (1) Niemur series (Niemur clay - various phases). (2) Tulia series (Tulla lo8Ill, Tulla clay-loam). (3) Yarraman series (Yarraman clay-loam, Yarraman clay) o (4) ·Thyra series (Thyra clay-loam, Thyra clay). (1) Niemur clay is a variable soil and there are several mases of this tyi:;e. The normal phase is an uneven gilgai formation heavily timbered with black box. There is little .or no actual surface soil although a depth of 2 inches of grey light clay may occur on the shelf between the puff and the crabhole. The subsoil is a dark grey heavy clay, which is usually very lumpy and subject to considerable cracking in dry seasons. Small nodules of lime and limestone rubble are frequently present on the surface and in the soil itself to a considerable depth. ·The deep subsoil is a lighter grey cdlour and is a stiff and intractable heavy clay. Gypsum is usually absent, but there is a gypseous phase of Niemur clay which occurs near th:! creeks. The puffs are larger and the 13 crabholes smoother than in the normal type. Gypsum occurs as large crystals below 24 inches. Nearer the creeks and in the swampy depressions there is less-pronounc~d gilgai form­ ation. The plain phase of Niemur clay occurs as depressions in the treeless plains. These depressions receive much water as run-off from the surrounding plain and display typical gilgai formation. Gypsum is more frequently present in this phase than in those nearer the creeks (Plate 1, Fig.1).

(2) The Tulla soil series occurs in close association with the Niemur clay, on the, creek frontages in the northern area. It would appear that the Tulla soils, owing to their some­ what higher topographical position, have been less influenced by flooding. Tulla loam ·is a silty soil, which occurs along the banks of gullies that have a seasonal flow of water. This type has 6 inches of light grey silty loam or silty clay-loam surface over a mottled yellow and grey silty medium clay subsoil. The ·texture is a silty clay by 30 inches and may go to silty clay-loam or fine sandy clay-loam by 48 inches. The deep subsoil is characterized by much rusty brown and black mottling. There may be a trace of lime or rubble about 30 inches. Tulla loam is very restricted in occurrence and is of minor importan~e. Tulla clay-loam occurs in larger areas. The surface is only slightly con­ torted by gilgai, if at all. There is 2 to 4 inches of grey clay-loam surface and the subsoil is a dark yellowish grey heavy-clay, which is not so lumpy as Niemur clay. There is usually lime and rubble pre sent at 12 to 15 inches and the clay of the deep subsoil usually becomes lighter in texture. There may be soJM fine crystalline gypsum present in the deep subsoil. Tulla clay-loam is frequently the marginal soil between Niemur clay and the heavy clay soils of the plains.

(3) The Yarraman series in the south replaces the Tulla series in association with Niemur clay and occurs also in association with Womboota loam as depressions in the plains. Yarraman clay-loam displays only slight gilgai formation. The surface is a light grey clay-loam characterized by the presence of small round ironstone concretions or buckshot about the size of a pea, both on the surface and in the soil itself. The surface depth is usually 4 or 5 inches, the lower inch or two being a very light grey in colour. The subsoil is a dark yellowish grey colour going to yellow-grey somewhat lumpy clay. Lime and rubble are usually pre sent at 15 to 18 inches but absent from the deep subsoil, which is 14 usually lighter in texture. Yarraman clay shows various degrees of gilgai developmmt and, in soJIE cases, is vecy dist~rted; the depression being up to 30 feet in diameter, and a depth of 3 feet from top of puff to bottom of depress­ ion is not unusual. The surface is liberally scattered with buckshot which also occurs throughout the soil to a depth of 3 or 4 feet. The re is only about 1 inch of grey light clay surface soil over a darkish yellow-grey, vecy lumpy clay sub­ soil. Liioo occurs between 6 and 12 inches and. the deep sub­ soil is a grey mottled heavy clay • . Gypsum may occur at 36 ~o 42 inches. (4) Thyra series is the grey-brown counterpart of the Yarraman series. Thyra clay displays the greater gilgai dis­ tortion of Yarraman clay and has similar quantities of buck­ shot on the surface and through the soil (Plate 3, Fig.l). The surfac~ soil consists of about 2 inches of grey-brown clay-loam or light clay mottled with black and yellow. Some lime is noticeable at 6 to 8 inches and the deep subsoil is a grey lumpy heavy clay mottled with yellow, brown, and black. The surface of Thyra clay-loam displays some puff and crabhole developIIEnt, but buckshot is rarely present. About 2 inches of grey-brown clay-loam surface is usual. The general characteristics of the subsoil are similar to those of Thyra clay, but gypsum is frequently present as coarse ccystals in the deep subsoil.

(iii) Grey and Brown Soils of the Treeless Plains.- The group comprises heavy clay soils with shallow surfaces which frequently manifest various degrees of gilgai formation. The following soil ty~ s have been included in this group:

(1) Marah loam. (2) Mundiwa loam. (3) Tomara loam. (4) Billabong clay. (5) Colimo clay. (6) Riverina clay. (7) Noorong clay-loam. (8) Yallakool clay-loam. (9) Moulamein clay.

(1) Marah loam is a soil intermediate between the Deni­ boota loam and the heavier plain soils. It is confined to the northern and central areas. There is usually less than 3 inches of brown· loam or clay-loam surface. The subsoil is a dark brown or dark reddish brown clay going to a brown clay with some slight lime and lillEstone rubble accumulations at 12 to 15 inches. Below 21 inches the deep subsoil becomes 15 yellow-grey in colour and lighter in texture, frequently going to fine sandy clay by 48 inches, but usually becoming a clay once again with depth. Characteristic of Marah loam is the occurrence of fine, crystalline gypsum in considerable concentrations at 21 to 27 inches and persisting to some extent to depth, but becoming more coarsely crystalline. There is a phase of Marah loam that is incipiently crabholed. This phenomenon is apparent as small areas of 2 or 3 feet diameter, which show surface cracking and appear to be slightly depressed. These areas have very little surface soil and usually are apparent by the darker brown colour displayed. In this phase there is less lime and more gypsum present than in the normal phase. Marah loam Ilr3rges somewhat into Mundiwa loam in the south central area.

(2) Mundiwa loam is in many respects similar to the Marah loam, but the textures are heavier throughout, there being no lightening off in the deep subsoil. Also, the surface depth is greater, there being 4 inches of brown loam over a warm brown subsoil. The re is usually no lillr3 pre sent, but crystalline gypsum always occurs about 27 inches. The gypsum may persist in coarse, crystalline form to 7 feet or more. The deep subsoil is a grey clay mottled with brown, yellow, and black.

(3) Tomara loam is found often associated with Mundiwa loam as small, almost treeless, plains in areas of Womboota loam (Plate 2, Figo2). Soil characteristics such as colour and texture are similar to Mundiwa loam, but gypsum is absent except for rare cases where small amounts of coarse, crystal­ line gypsum may occur below 39 inches. Lillr3 in slight con­ centrations usually appears at 15 inches and is absent again by 24 inches. There were case·s noted where no lime occurred in this soil type.

(4) Billabong clay is the brown or grey-brown soil of the treeless plains. The surface is usually one-half to an inch in depth and is a light clay. The dark grey-brown subsoil is a very stiff heavy clay, which becomes very sticky and intractable when wet. The re is a tendency to gilgai f onn­ ation, the crabhole being fairly well developed, but the puff only slightly so. The re may be a trace of lillr3 and fine rubble in the grey-brown clay at 15 to 18 inches. The deep subsoil is grey with some brown, yellow, and black mottling and is a heavy clay. Gypsum occurs in the coarsely crystal- 16

line form in nedium concentrations between 30 and 33 inches. The incipiently crabholey phase of Billabong clay has a brown or dull brown surface which displays incipient crabhole formation. The subsoil is dark brown, and fine, crystalline gypsum occurs in zmdium to heavy concentrations at 21 to 27 inches. The gypsum becozms less concentrated but more coarsely, crystalline with depth.

(5) Colimo clay is intermediate between Billabong clay and the grey Riverina clay. The surface is brownish grey in colour with more pronounced gi.lgai development than Billabong clay. One half to three inches of clay-loam or light clay surface overlies the dark brownish grey, rather crumbly sub­ soil. A trace of 1~ frequently occurs at 10 to 15 inches, where there is usually some crystalline gypsum. This in­ creases in quantity and becomes more coarsely crystalline to a depth of 30 inches in the grey mottled deep subsoilo Gypsum persists to greater depths in pockets. The dense phase of Colimo clay is distinguished by the cloddy* nature of the subsoil.

(6) Riverina clay is the most commonly oceurring soil type in the area (Plate 1, Fig.2). It is the grey, heavy soil of the treeless plains, and the surface manifests varying degrees of gilgai developm:int, though never to the extent of qistortion found in Niemur clay. Surface colour is grey or light grey. Surface depth varies from practically nil oq the puff and in the crabhole to depths of up to 6 inches on the intervening shelf. The subsoil is a darkish grey, lumpy, heavy clay, which is very stiff and sticky when wet. The deep subsoil is grey, heavy clay with yellow, brown, and black mottles. Gypsum usually ·does not appear before 30 inches and is coarsely crystalline and in smaller concen­ trations than in Billabong or Colimo clayo Pockets of coarsely crystalline gypsum persist in the deep subsoil. The crabholey phaseof Riverina clay displays marked crabhole and puff development whereas the normal type is much more level with only slight gilgai formation.

(7) Noorong clay-loam and Yallakool clay-loam are similar soils to Riverina clay and Billabong clay or Colimo clay and _ occur on the plains of the Wakool Irrigation District adjac- *A "cloddy" soil is one whose lumps are 4 or 8 inches in diameter, or even larger. 17 ent to tre Deniboota Irrigation District. Vecy small areas of these soil types occur with Riverina clay in the extreme western portion of the Deniboota Irrigation District. Noorong clay-loam is similar in surface characteristics to Riverina clay, but the clay subsoil below 24 inches is much lighter in texture.

(8) Yallakool clay-loam resembles the grey-brown Billabong clay or the brown-grey Colimo clay, but also has a lighter­ textured clay in the deep subsoil. Both these soil types are characterized by the growth of dillon bush, which is found only rarely on Riverina or Billabong clays. (9) Moulamein clay is somewhat similar to the plain phase of Niemur clay. It also occurs in the adjoining Wakool Irrigation District and vecy small areas are found, together with Noorong and Yallakool clay-loams, in the west of the area. The surface is considerably contorted by puffs and crabholes, is a dark grey colour, and supports dillon bush. The puffs have "self-mulching"* surfaces.

(iv) The Soils of the Sandhills.- These are represented by Sandmount sand and the shallow phase of the same soil type. Sandmount sand is a brown sand to depth, but the shallow phase of Sandmount sand has a sandy clay occurring between 24 and 30 inches, changing to a sand again at lower depths.

(v) Soil Complexes.- These complexes are associated with streamlines. The first is the Cochran-Yarrein Creek complex, which was first encountered and named in the adjoining Wakool Irrigation District (Smith, Herriot, and Johnston 1943). It consists of a miscellaneous collection of variable soils along the seasonal Cochran's Creek. These soils are too mixed to be mapped, as they vary from heavy clays to sand­ hills. The second complex comprises the soils in and along­ side Green Gully in the south and is named the Green Gully complex. The soils in the gully bed are variable, heavy, grey soils that become grey-brown and lighter towards the sides of the gully. The slopes to the gully banks and the banks themselves are brown, light soils resembling Bunnaloo loam. At various spots along Gree~ Gully are elongated low *Certain surface soils have physical characteristics which enable them on dcying to crumbll? or powder, whereas others set hard. This crumbling on dcying is termed "self-mulching". 18 rises, which are old gypsum dunes with deposits of kopi just beneath the brown clay surface extending to a depth of 18 inches to 3 feet. (vi) The Soils of the Dry Stream Beds.- The streams referred to are non-functional streams of various kinds that carry water only for an hour or two after very heavy rains. The soils are characterized by permeable, sandy bottoms and are dealt with in three broad groups:

(1) Brown soils = Type !• (2) Grey, sandy soils= Type ~- (3) Grey, heavy soils W'¼th sandy, deep subsoil= Type Q.

TABLE 1

AREAS OF SOIL ASSOCIATIONS PRESENT IN THE DENIBOOTA IRRIGATION DISTRICT (ACRE S)

Deniboota - Purdanima association 18,000 Bunnaloo loam 9,000 Womboota loam 25,000 Wongal clay-loam 2,000 Tulla-Niemur association 50,000 Yarraman series 7,000 Thyra series 1,000 Mara.h loam 21,000 Mundiwa loam 8,000 Tamara loam 5,000 Billabong - Riverina association 100,000 Sana.mount sand 1,000 Soil complexes 10,000 Total 257,000

(1) The brown stream beds in the northern and central area are usually sandy, but solffi resemble Deniboot a sandy loam in some aspects. The southern stream beds belonging to this group usually show similar characteristics to Bunnaloo loam, which is the soil of the levees, but are more sandy in the deep subsoil.

(2) The grey, sandy stream beds occur in the north and central area in association with Riverina and Billabong clays. 19

(3) The grey, heavy soils occur in larger stream beds and closely resemble Niemur clay. The surface is contorted by gilgai formation and the subsoil is a dark grey, heavy clay, but the deep subsoil at 3 to 4 feet suddenly changes to a fine, sandy clay. (c) Relation of Native Vegetation to Soil Types Table 2 summarizes the relationship between individual soil types and native vegetation as observed during the sur­ vey. It should be emphasized that while this relationship commonly holds, it is not perfect and soil types should not, therefore, be guessed from the vegetation alone. The topo­ graphic occurrence of the soils as given under type descrip­ tions earlier is a useful additional guide.

(d) Salt There is a rather high concentration (0.3 per cent.) of common salt (sodium chloride) in the deep subsoil of the majority of the soils of the area. The presence of this salt at depths of 3 to 4 feet does not irean that the soil is unsuit­ able for irrigation, but that care must be taken not to allow water-tables to develop. The salt becomes dissolved in the ground water and, as the water-table rises, so the salts are carried upwards through the soil. Should the water-table recede much of this salt crystallizes out and remains , at the higher level. In this way high concentrations of salt are built up close to the surface of the soil. If these salt concentrations are in the zone of root growth they have a toxic effect on the plant, either depressing its growth or killing it altogether. Once this stage has been reached, reclamation is a long and costly process. As the chief cause of water-tables developing is overwatering, their formation can be largely averted by careful irrigation practices, which include great care in irrigation layout to ensure an even water distribution over the surface.

The accompanying Table 3 gives average salt content for the fourth foot of the soil. It will be seen that the grey soils subject to inundation and Purdanima sandy loam have relativ­ ely low figures. The remaining red-brown earths have a much higher salt figure, whilst the grey and brown soils of the treeless plains are higher still. It is not, however, the amount of salt pre sent, but rather the freedom with which ·rABLE 2 VEJETATIOO IN RELATION TO SOIL TYPE I\) 0 Trees and Shrubs Grasses Herbage Soil Type Dominant Associated Dominant Associated Dominant Associated

Purdanima sand Murray pine Tea-tree Spear grass Wallaby grass Blue crowfoot Burr medic Bull oak Berrigan Tussock grass Prickly saltwort Purdanima sandy Needlewood Quandong loam (

Murray pine Needlewood Spear grass Creeping salt Burr medic Bull oak Berrigan Wallaby grass bush Prickly saltwort Deniboota sandy Rosewood Salt weed loam T~a-tree Blue crowfoot Ironwood Tussock grass Deniboota loam Cooba Boree

Murray pine Bull oak Spear grass Rat's-tail Blue crowfoot Bunnaloo loam Grey box Needlewood Wallaby grass fescue

Grey box Murray pine Wallaby grass Rat's-tail Blue crowfoot Creeping saltbush Womboota loam Bull oak Black box Spear grass fescue Saltweed (rare)

Wongal clay-loam .Black box Wallaby grass

Bull oak Wallaby grass Rat's-tail Lichen Common crowfoot Tamara loam (rare) fescue Spear grass Fairy grass

Bull oak Boree Wallaby grass Mundiwa loam (rare) (rare) Rat's-tail Lichen Conman crowfoot fe~cue Creeping saltbush Spear grass Slender-fruited Fairy grass saltl:lush Saltl1eed TABLE 2 (Continued) Trees and Shrubs ·Grasses Herbage Soil Type ,-----A- Dominant Associated Dominant Associated Dominant Associated Marah loam Boree Cooba Wallaby grass Spear grass Salt-weed Slender-fruited Fairy grass Creeping salt- saltbush bush

Billabong cla;y Boree (rare) Lignum Wallaby grass Windmill grass Saltweed Roly poly (M.coccolo- Fairy grass ~) Cotton bush

Boree (rare) Cotton bush Wallaby grass Fairy grass Roly poly Poverty weed Ri verina clay Black box Dillon bush Windmill grass Rat's-tail Sal tweed Burr medic Colimo clay (rare) (rare) fescue Everlasting daisies Lignum ( rare )

Tulla clay-loam Black box Ironwood Wallaby grass Spear grass Burr medic Lignum Bull oak Roly poly

Black box Red gum Wallaby grass Swamp wallaby Roly poly Reeds ~ Lignum Ironwood grass Burr medic Rushes Niemur clay Boree Cane grass Poverty weed Nardoo Cooba Windmill grass Saltweed Indigo bush

Yarrama:n cla;y- Black box Lignum Wallaby grass loam Yarraman clay

Thyra clay-loam Black box Bull 011k Spear grass Spear grass Thyra cla;y Wallaby grass Rat's-tail - N fescue -->.

/ I'\) I'\) TABLE 2 (Continued)

Trees and Shrubs Grasses Herbage Soil Type Dominant Associated Dominant Associated Dominant Associated Cochran-Yarrein Murray pine Bull oak Spear grass Wallaby grass Blue crowfoot Prickly saltwort Creek complex (on sandhills) Black box Red gum

Gre,m Gully Black box Wallaby grass Complex

Sandmount sand Murray pine Bull oak Spear grass Blue crowfoot (northern area) Hop bush

Sandmount sand Murray pine Grey box Spear grass Blue crowfoot ( southern are a) Yellow box

Stream bed soil Murray pine Spear grass Rat's-tail Blue crowfoot Burr medic A Needlewood Wallaby grass fescue Prickly saltwort Yellow box Tussock grass Black box \·/indmill grass (All rare)

Stream bed soil Black box Murray pine Spear grass Rat's-tail Blue crowfoot Burr medic ~ Wallaby grass fescue Prickly saltwort Tussock grass Windmill grass Stream bed soil Black box Lignum Wallaby grass Swamp wallaby Roly poly f Indigo bush grass Poverty weed 23 water can move through the soil that is of greatest import­ ance. The Deniboota, Bunnaloo, and Marah series have light, deep subsoils, and, especially where a heavy layer occurs as a deeper horizon, there is a distinct possibility of perched

TABLE 3

SALT (NaCl) CONTENT OF DENIBOOTA SOILS AT A DEPTH OF FOUR FEET

Soil Type Average Salt Content (%)

Purdanima sandy loam 0.12 Deniboota sandy loam 0.30 Deniboota loam 0.32 Deniboota loam - light profile phase 0.29 Bunnaloo loam 0.21 Bunnaloo loam - heavy subsoil phase 0.34 Womboota loam 0.24 Womboota loam - heavy profile phase 0.25 Tulla clay-loam 0.22 Niemur clay 0.19 Niemur clay - plain piase 0.20 Niemur clay - gypseous phase 0.15 Yarraman clay-loam 0.10 Yarraman clay 0.10 Thyra clay-loam 0.18 Marah loam 0.37 Marah loam - incipiently crabholey piase 0.39 Mundiwa loam 0.37 Tomara loam 0.36 Billabong clay 0.50 Colimo clay 0.41 Colimo clay - Yaloke piase 0.37 Rive rina clay 0.36 Riverina clay - Warbreccan piase 0.42 Stream bed soil type A 0.05 Stream bed soil type B 0.01 Stream bed soil type Q 0.17 24

TABLE 4

PROPCSED ( OR TENTATIVE) RELATIONSHIP OF THE SOII.S TO IRRIGATED PASTURES AND CROPS

@ @ ,-.:i ,-.:i @ @ ,...; ,rj I >, ,rj ~ ,...; @ @ ~ ~ § al ~ al i al @ @ I ,...; ~ ~ ,...; ,...; ~ al CIJ CIJ CIJ ,-.:i I ,...; I @ 0 ,...; CIJ ,-.:i ,-.:i ~ ~ /8 0 0 al al al ,...; ~ ,...; ~ ~ ,-.:i ~ ~ +' 0 al 0 ,...; 0 ~ ,...; ,...; ~ ,-.:i 0 .i -~ b b 0 +' 0 0 0 ,-.:i § ~ § ~ ~ 0 0 ,...; 0 ,...; ~ al .0 0 ·rl 0 .0 .0 al 0 al al ~ ! al al ·rl 1-, al 1-, •rl •rl bO ,...; 1-, i1-, 1-, 1-, ,rj ,...; ~ ~ s ~ al ,i3 Q) -~ ~ ~ 1-, 1-, >, 1-, ,...; ,...; ~ ~ ~ ~ Q) Q) § § •rl § 0 Crop p... p... ~ 'd al al .& ..c: a •rl •rl al A A ~ 13:: 13:: E-l z I>< I>< E-l E-l ~ ::.1 E-l ~ 0 p:; CIJ

Rice p p p p p p p p G p p p p p F F G G G p

Citrus G G F F F p p p p p p p p p p p p p . p G

Pane fruits p p p F F G p p p p p p p p p p p p p p

Stone fruits p p p F G F p p p p p p p p p p p p p p

Lucerne (hay) G G G G G F p p p p p p p p p p p p p p

Lucerne (grazing) G G G G G G G G G F F F p p p p p p p p

Winter pasture F F F G G G G G G G G G p F F F p p p p

Summer pasture F F F G G G G G G G G G p F F F p p p p

Winter-summer pasture F F F G G G G .G G G G G p F F F p p p p

Irrigated cereals F F G G G G G G G G G p F F F F F F p ( summer) F Irrigated cereals G G G G G G G G G G G G p F F F F F F p (winter)

Key: G = good, F = fair, P = poor.

Winter pasture, e.g. Wimmera rye grass and subterranean clover. Summer pasture, e.g. paspalum, Rhodes grass, ki kuyu, strawberry clover, and white dutch clover. Winter-summer pasture, e . g. paspalum or kikuyu - white clover or strawberry clover and Wimmera rye grass, subterranean clover. Irrigated cereals (summer), e . g. maize, sorghum, mil~et, Sudan grass . Irrigated cereals (winter), e . g . wheat, oats, barley. 25 water-tables developing. Billabong clay is a heavy, imperm­ eable soil and, despite the higher salt concentrations, is unlikely to suffer from water-table troubles.

The majority of the Deniboota soils are much more salty than re_lated soil types in surrounding district,s.

(e) Soils in relation to Irrigated Pastures and Crops No direct data is available as to the actual response of these soils under irrigation as the district has not yet been supplied with water. This discussion is based on the . correlation between the soil types represented in the Deni­ boota Irrigation District and the known potentials of related soil types in adjacent established irrigation areas. All the soils of the area are conspicuously phosphate­ deficient and need heavy dressings of superphosphate to achieve results frcm irrigation(See Tabl e 4). (i) Red-brown Earths This soil group canprises the majority of the lighter, bett·er-drained soil members and it is in this group that we find the most attractive soils for irrigation in the area. (1) Purdanima Soil Series.- Much of this series will not be commandable by the channel system owing to its elevation above the surrounding plain. Spray irrigation should be practised where home orchards are planted on these soils, especially on Purdanima sand, which would be unsuited to flood irrigation. Where gravity irrigation can be carried out these soils should be well suited to lucerne growing" Sumner and winter past ures will give good results, but there is a distinct likelihood of seepage problems occurring in adjacent soils. The hardpan has yet to be proved a barrier to root and water i:enetration, as has been demonstrated on t he Falkiner Memorial Field Station, Deniliquin (personal communication). There is, however, a tendency for a com­ pacted Of slightly ceirented layer of soil to be formed near t he surface (i.e. at approximately 6 inches). This layer is very impermeable and greatly impedes both root and water penetration. Where this layer is found to be present irrigation is not recommended. There is a distinct possib­ ility that water-tables may form in these soils should excess water be applied, but under safe irrigation practices the well-drained deep subsoil should be an advantage only. 26

The greatest difficu.lty to be encountered with the Purdanima series will be the layout for irrigation. Should the gradient be too great or too little there will be difficulty in obtaining satisfactory results from irrigation.

(2) Deniboota Soil Series.- This also occ~rs in rather elevated areas, but except for an occasional patch of Deni­ boota sandy loam this should all be commandable by the channel system. These soils will probably develop the great­ est problems in irrigation of any in the area. The Deniboota sandy loam should behave very much as the Purdanima soils, but the Deniboota loam has some features undesirable in a soil for irrigation. The surface is a compacted soil that does not readily absorb water and sets hard after wetting. Should the slope be too_steep very little water would enter the soil during irrigation. This will tend to prevent germ­ inating seedlings emerging through the soil.* The subsoil is crumbly and should allow good water penetration once the surface barrier has been passed, and the deep subsoil is light and should allow for satisfactory internal drainage. However, in some cases a clay horizon occurs at depths of about 5 feet, which may lead to the fonnation of water­ tables at an early date. These soils are salty in the deep subsoil and the formation of water-tables would cause the salt to rise to the surface. This will eventually ki+.l all plants as the concentration of salt increases. With approp­ riate tillage and drainage practices Deniboota soil series should prove excellent for winter and sUIIJIOOr pasture crops and summer fodder crops, and, in mos~ cases, give very reasonable stands of lucerne.

(3) Bunnaloo Loam has similar characteristics to the Deni­ boota loam but not to such a marked degree. However, there is a likelihood of water-tables building up under unsuitable irrigation techniques, owing to the frequent presence of the clay horizon in the deep subsoil. The salt content of this clay layer is rather high and great care should be taken when irrigating this phase of Bunnaloo loam as there is a likeli­ hood of salt rising. Pasture and forage crops should be somewhat better than with Deniboota loam. The Cobram and Finley loams (Berriquin Irrigation District) are related *The actual emergence of the pJ_.ant through the soil crust is known as "brairding" and will be referred to hereafter as such. 27 soils where lucerne, Wimmera rye, subterranean clover, and SUIIllmr pastures and fodders have done well. The Cob ram soil series in County Moira, Victoria, has proved to be well suited to stone fruit growing and the Bunnaloo loam may have distinct possibilities in this direction.

(4) Womboota Loam.- This is a heavier soil than those mentioned above. Surface characteristics are similar to Bunnaloo loam, but the clay subsoil, although quite satis­ factory for irrigation, is less permeable to water. The deep subsoil does not become very light and it may be inferred_ that lucerne would be a good grazing proposition, but less desirable as a hay crop. Winter and summer pastures should give very good results, as should wheat and the summer fod~er crops such as maize, sorghum, millet, etc. Should the southern portion of the area be converted to dairying these soils should give excellent results under paspalum, Rhodes, and Sudan grass. Womboota loam is similar to Moira loam in County Moira, Victoria, which has proved a reliable and satisfactory soil for pasture and fodder crops and is also used extensively for pome fruit growing.

(5) Wongal Clay-loam is marginal between the Womboota loam and the heavier gilgai complexes of the creek frontages • . It resembles the heavy profile phase of Moira loam (-Murray Valley Irrigation District) and should be a satisfactory medium for pastures and cereals.

The red-brown earths have s everal advantages in irrigation layout:

(a) The slope, except in Purdanima series, is usually moderate, and irrigation layout in small bays should be simple with no great amount of grading to be done. (b) There is usually only a thin stand of trees, which would minimize clearing expenses. (c) These soils are associated with old, well-drained non-functional streams, which in many instances will provide natural drainage. channels for excess water.

The disadvantages are:

(a) The hard-setting surface soil. 28

(b) The likelihood of water-tables forming. (c) The high salt content of the deep subsoil.

(ii) Grey Soils Subject to Inundation

(1) Niemur Clay.- The most important and most extensively occurring member of this group of soils is Niemur clay. This soil has a high natural fertility and is used in the Wakool Irrigation District for winter pastures. Where the surface of the soil is somewhat ·self-mulching (crumbles when dry) no great brairding difficulties should be encountered. Although these soils are heavy and lacking internal drain­ age, waterings will not be ·sufficiently heavy to give rise to water-tables . The natural salt content is genArally low in this soil. There are rather serious disadvantages to the use of Niemur clay for irrigated pastures and crops. These are:

(a) Niemur clay is a pronounced gilgai complex and grading into bays is. an expensive processo (b) Most of the Niemur clay is heavily timbered with b'iack box and red gum, and costs of clearing are heavy. (c) Much is liable to flooding from the adjoinin~ streams. The construction of levees would make these areas suitable for irrigation. However, such levees inter­ fere with the natural surface drainage and can cause further problems to arise. · (d) Should an irrigated pasture become flooded, due for instance to heavy rain after irrigation, there is _a distinct risk that the graded soil will again form uneven· gilgai ccmplex.

These disadvantages by no In3ans precluds the use of this soil for irrigated crops. In many cases areas may be located with a minimum of gilgai _and timber and, therefore, could be used with less expense. The phase of Niemur clay found on the plains is considered to be less fertile than its equivalent along the creek frontages and possibly somewhat salty. Such crops as wheat, oats, rice, barley, maize, sor­ ghum, and millet ryave all given good results on Niemur clay in the adjacent Wakool Irrigation District and even lucerne has made good progress as a grazing proposition. Paspalum, kikuyu, and Rhodes grass all do well on Niemur clay. 29 (2) Tulla Series.- This is in much the same category as Niemur clay. It is t9pographically higher, not so crabholey, and is usually less heavily timbered than· Niemur clay and hence would be less expensive to lay out for irrigation. Its occurrence is only a small fraction of that of Niemur clay, but it should prove a satisfactory irrigation soil for all winter pastures and s~r fodder crops.

(3) Yarraman Clay-loam and Yarraman Clay.- Both are new soil types in the region and little is known of their behav- -iour under irrigation. · It might fairly safely be assumed that many of the remarks regarding Niemur clay and Tulla clay­ loam could quite well be applied to Yarraman clay and Yarra­ man clay-loam respectively. As with Niemur clay, Yarraman clay is strongly gilgaied. Some of this would be virtually impossible to grade into a flat bay. It is heavily timbered with black box though somewhat less liable to flooding· than Niemur clay. The Yarraman clay of the plains is probably less salty than the equivalent ph_ase of Niemur clay. The fact that Yarraman clay-loam becomes light in the deep sub­ soil leads to the impression that this soil type may be suit­ able for irrigation. Pastures and fodder crops should respond on these soils as for Niemur clay and Tulla clay-loam respectively. There is the likelihood that much of .the Yarraman series may be unsuitable for irrigation owing to its topographical position. There may be a serious drainage problem as the Yarraman series usually occurs in the lowest and most poorly drained positions. (4) Thyra Series.- This is also newly na:rmd and little is known of its potentialities. Thyra clay is an unsuitable soil as the gilgai complex is so pronounced as to preclude grading. Thyra clay-loam is a distant relative of Naring loam in County Moira, Victoria, and should be a reasonable pasture and cereal soil. (iii) The Grey and ?rown Soils .of the Treeless Plains These make up the greatest percentage (almost 50 per cent.) of soils of the area and are the least attractive. They are all high in salt, and have undesirable surface conditions (cake on drying). They are more or less imperiooable clays.

(1) Marah Loam has a shallow surface and a reasonably perm­ eable subsoil. The deep subsoil is light-textured, but high in salt. A naturally infertile soil, it will probably give 30 rise to serious problems under irrigation, especially where found in conjunction with irrigated red-brown earths. In such cases lateral movement of irrigation water within the soil may develop water-tables in the Marah loam. This will result in the salt being brought up into the root zone. It is not expected that pastures will give satisfa~tory results on this soil type, but probably fair results would be obtained with such crops as wheat, millet, sorghum, etc.

(2) Mundiwa Loam and (3) Tomara Loam.~ Both are similar in characteristics to the Marah loam, but have a deeper surface of more friable loam and ·are heavier in the subsoil. The sub­ soil is probably less permeable than in Marah loam and there is less likelihood of water-tables developing. Both Mundiwa and Tomara loams will conform to the remarks on Mara.h loam regarding crops, but slightly better results may be expected. These three soil types mentioned above have very level sur­ faces and can be la.id out to irrigation with the minimum of labour and expense. It will be seen from the foregoing remarks, however, that the results expected may be small (Plate 2,Fig.l).

(4) Billabong Clay, (5) Colimo Clay, and (6) Riverina Clay.­ These may be dealt with collectively. They all have shallow surfaces that tend to cake very badly and depress brairding. The subsoil is lumpy clay, which becomes stiff and intractable when wet and the deep subsoil is heavy and of high salt content. Although various degrees of gilgai are present, most of the areas of these soils are flat and easy to lay out. All are naturally infertile, with Billabong clay the least fertile. Little success has been achieved with pastures under irrigation on this type of soil. On the similar Noorong clay-loam in the Wakool Irrigation District, pastures have deteriorated rather than improved with age. At the present time these soils cannot be recommended for any use except irrigated cereals, particularly rice.

(7) The Soils of the Sandhills.- Being too high to be corrrrnanded by water from the channel system, Sandmount sand is an uneconomical pasture and fodder crop proposition owing to the expense of pumping water from the channels. There are several fairly large areas (up to 250 acres) of sandhills to the north and west of Bunnaloo Siding that might be converted to citrus groves by lifting the water to heights of up _to 50 feet. 31

(8) Soil Complexes.- The Cochran-Yarrein Creek complex is a maze of creeks, gullies, and sandhills, and could not be used for irrigation. Much of · the Green Gully complex is steepl y sloping and dissected by gullies, but there are fre­ quent areas of gully bed which are composed of heavy grey soil similar to Niemur clay. These could be used for annual crops such as wheat, oats, maize, etc., but would probably be unsuitable for permanent pasture, except paspalum, owing to the risk of flooding from seasonal rains.

( 9) The Soils of the Dry Stream Beds occur only in narrow old streamlines and can thus be excluded from any irrigation possibilities~ Some indication of the irrigation potential of the Deniboota soils may be obtained by reference to similar soils in adjacent irrigation areas. The results obtained under irrigation in these related soils may be applied to the Deniboota soils, depending on the closeness of relatioR­ ship. Table 5 shows the related soils and indicates degree of relationship between these and the Deniboota soils.

(f) Classification of the Area as to Suitability for Irrigation Development

Limitations of water rights exclude the production of such crops as rice and horticultural crops so only pastures and fodder crops will be dealt with here.

Four categories of soils are here proposed in relation to their expected irrigation potential. The basis of these categories is founded on the internal drainage of the soils, their permeability to water, _and their natural fertility. The group! irrigation soils are those suitable for the growing of lucerne and pastures, the group~ soils are those suitable for pasture and sUIIJIIer fodder crops, doubtful soils are those not expected to be sufficiently productive to form an economic irrigation unit and unsuitable soils are those incapable of being irrigated owing to topographical features, e.g. sandhills, heavy gilgai formations, or country with many gullies. In the "unsuitable soils" of Table 6, Sand.mount sand and the two soil complexes are topographically unirrigable, whilst the Niemur, Thyra, and Yarram clays, which are too uneven or dissected by gullies, and the red-brown earths, which are not comrnandable by the channel system, are included as "other" types. \

TABLE 5 RELATIONSHIP BETWEEN THE OOILS OF THE DEN:BOOTA IRRIGATION DISTRICT AND THOSE OF SURROUNDING DISTRICTS vJ r'0 Soil Type Soil Type to­ Area of Degree of Remarks (Deniboota Irrigation Which Related Occurrence Relationship District)

Purdanima sandy loam Katunga sandy Pine Lodge Estate, Close The cemented hardpan is not so loam Tocumwal. Murray coarse in Purdanima series Valley Irrigation Close District

Deniboota sandy loam Waaia sandy Murray Valley Close Subsoil more dense and higher salt loam Irrigation District figures for Deniboota sandy loam

Deniboota loam Waaia loam - Murray Valley Moderate Surface soil more compact and sandy subsoil Irrigation District gypsum present in subsoil of phase Deniboota loam. Also higher salt figures

Deniboota loam - light Wakool loam Wakool Irrigation Close Surface soil more compact and profile phase District frequent presence of gypsum in subsoil of Deniboota loam - light profile phase Bunnaloo loam Cobram loam County Moira, Close Higher salt content of Bunnaloo Victoria loam and frequent presence of heavy layer in deep subsoil

Womboota loam Finley loam Pine Lodge Estate, Moderate Less salt in deep subsoil of Finley Tocumwal · loam. Subsoil more crumbly in Finley loam Wongal clay-loam Moira loam - Murray Valley Close heavy profile Irrigation District phase

Tulla clay-loam Tulla clay­ Wakool Irrigation Close loam District

Niemur clay Niemur clay · Wakool Irrigation Close District TABLE 5 (Continued) Soil Type Soil Type to Area of Degree of Remarks (Deniboota Irrigation Which Related Occurrence Relationship District)

Yarraman clay-loam Boosey clay­ Murray Valley Close Boosey clay-loam somewhat darker loam Irrigation District colour throughout, and gypsum ma;y be present in deep subsoil. Both occur as grey depressions in red­ brown earths Yarraman clay Muckatah Cl8il"­ County Moira, Distant More buckshot on surface of Yarraman loam Victoria clay and colour predominantly yellow in subsoil as against dark grey in Muckatah cley-loam

Thyra cley-loam Naring loam County Moira, Distant Surface soil heavier and tendency Victoria to puff formation. Deep subsoil of Thyra clay-loam more salty and may contain gypsum Marah loam Mundiwa loam Berriquin Irrigation Distant Surface soil more dense, more red District colour in subsoil as against dark brown in Mundiwa loam. Deep sub­ soil lighter and more salt present

Mundiwa loam Mundiwa loam Berriquin Irrigation Close Somewhat more salty in deep subsoil District

Mundiwa loam Picola loam Murray Valley Close Much more salt in deep subsoil of Irrigation District Mundiwa loam

Tomara loam Picola loam Murray Valley Moderate More salt in deep subsoil and Irrigation District gypsum usually absent in Tomara loam

Billabong Clay Billabong clay Berriqu.in Irrigation Close District vJ \.N '

\.>I TABLE 5 (Continued) -i::-

Soil Type Soil Type to Area of Degree of Remarks (Deniboota Irrigation Which Related Occurren ce Relationship District)

Billabong clay Yallakool clay­ Wakool Irrigation · Distant Heavier surface and deep subsoil , loam District and browner colour throu.ghout Billabong clay. No dillon bush

Colimo clay Yallakool clay­ Wakool Irrigation Distant Heavier surface and deep subsoil. loam District No dillon bush. Subsoil much more crumbly in Colimo clay

Colimo clay - dense Yallakool clay­ Wakool Irrigation Moderate Heavier surface and deep subsoil. phase loam District No dillon bush

Ri verina clay Riverina clay Berriquin Irri­ Close gation District

Riverina clay Noorong clay­ Wakool Irrigation Distant Heavier surface and deep subsoil. loam District No dillon bush

Riverina clay Mywee clay County Moira, Distant Mywee clay has darker grey colour and Victoria gypsum frequently absent

Sandmount sand Sandmount sand County Moira, Close Victoria Wakool Irrigation Close District Berriquin Irri­ Close gation District 35

TABLE 6

CLASSIFICATION OF SOIL TYPES INTO CATEGORIES ON SUITABILITY FOR IRRIGATION AND ACTUAL ACREAGE OF EACH CATEGORY

Category Soil Type Area Total Area Area (acres) (acres) (%)

Suitable Bunnaloo loam 17,700 Group! Womboota loam 30,150 Deniboota sandy loam} 70,850 23.4 Deniboota loam 23,000 Purdanima sand Purdanima sandy loam

Suitable Niemur clay } Group~ Tulla clay-loam 43 ,ooo Thyra clay-loam } Thyra clay 1,500 Yarraman clay-loam} 54,000 17.8 Yarraman clay 7 ,ooo. Wongal clay-loam 2,500

Doubtful Marah loam 23,180 Mundiwa loam 16,410 Tamara loam 6,000 Riverina clay } Colimo clay 105,934 151,524 50.0 Billabong clay

Unsuitable Sandmount sand 1,750 Cochran-Yarrein Ck. complex 8,420 26,690 8.8 Green Gully complex 3,660 Other 12,860 36

A reference to the soil map will show that over two-thirds of the red-brown earths are located in the southern third of the district. The remaining one-third of the red-brown earths occur as attenuated areas across the plain soils. The plain soils, which comprise 50 per cent. of the total area of soils present and are of doubtful irrigation value, occur as one large block covering most of the central and north-eastern portion of the district. The group~ suitable soils, the main members of which are Niemur clay and Tulla clay-loam, occur as a block along the creeks and rivers in the northern portion of the dlstrict. The scatter of soils is thus very restricted. Therefore the actual acreages of the different soils do not give a true picture of the area. From a crop point of view this means that there is very little soil suitable for lucerne in the northern and central areas, it being concentrated in the southern section. Much of the central portion is considered to be doubtful for irrigation development and large holdings are necessary to include a small area of irr:j.gated pastures and lucerne. The southern portion has an abundance of good irrigation soils. (g) Soil Erosion

The problem of soil erosion is not a serious one over most of the district. However, the disaggregated nature of the surfaces of most of the soils, coupled with the insidious effects of wind erosion, indicates that the problem could become acute with cultivation or overstocking. The areas previously sown to wheat in the northern areas have very little surface remaining and the cover of native grasses has been greatly diminished. Certain properties have been rather seriously overstocked and much surface soil has been lost as a result.

It seems certain that an inch or more of the surface soil of such types as Deniboota loam and Marah loam has been removed by wind quite recently. This seems to have occurred during the dry seasons of 1943 to 1945- as indicated by the records of surface depth during the reconnaissance soil survey carried out in 1942 and those showing shallower surface, during the detailed survey commenced in 1946.

The most spectacular effect of wind erosion is enccuntered on the Deniboota and Marah loams and takes the form of 11 scalds". These scalds are patches swept bare of vegetation, 37 ranging in diameter from a few yards to several chains. Almost all surface soil has been denuded and the clay subsoil is frequently exposed. Once e stablished these scalds will continue to enlarge until some approved method' of soil conservation is applied. The only plant able to establish itself, however sparsely, on these scalds is the hardy saltweed.

Other serious cases of wind erosion are to be found on certain sandhills in the southern area. The removal of the natural pine forests and cultivation for wheat growing has exposed these loosely coherent sands to the f.orces of wind erosion. This erosion (still actively proceeding) has already removed several feet of sand from some areas. There is little water erosion except along the banks of Green Gully. The rather light soils comprising the banks and the steepness of these slopes·render them very liable to the wa shing effects of surface run-off water from rain­ fall. At certain points along Green Gully this form of soil erosion is rapidly reaching serious proportions. Some system of contour furrowing would quickly halt erosion and repair the damage already caused. At least one landholder has recognized the need for such control and the results of his efforts are very satisfactory.

The problem of soil erosion in the Deniboota Irrigation District is, therefore, a matter which can be tackled personally by the individual concerned. If necessary action is taken at an early date there is no reason to expect the problem to become serious.

VI. ACKNOWLEDGMENTS

The author wishes to acknowledge with thanks the. assist­ ance given him by various persons and departments during the course of the survey.

The officers of the W.C.& I.e., Deniliquin, were cooper­ ative and helpful. The Postmaster, Deniliquin, Mr. F. Grant, supplied rainfall and temperature data as did the editor of the "Pastoral Times" newspaper, Miss A. Wyse. The Murray Shire Clerk, Mr. W.J. Dyer, supplied vital statistics on population trends in that Shire and the Commonwealth Meteorological Bureau supplied detailed meteorological data. for centres in an~ around the Deniboota Irrigation District. 38 The landholders of the area were always very helpful in supplying data on the pastoral and agricultural history of their properties. Mr. B. E. Butler, Regional Soils Officer, C.S.I.R.O., Deniliquin, supplied much constructive criticism and Mr. E.W. Boehm and Mr. C.H. Thompson, Soils Officers, C. S.I.R.O., ably assisted in the field work. A special acknowledgment i s due to the late M_r. P. E. Swaffer and Mr. A. J. F. Scott, who carriP. d the brunt of the manual labour involved, for their willing interest in the survey beyond the call of duty, which greatly assisted the author by relieving him of minor responsibilities. The salt analyses were carried out under the direction of Mr. J. T. Hutton, chemist, and the maps compiled by Mr. P. D. Hooper, Cartographer, both of the Division of Soils, C.S.I.R.O., Adelaide. Mr. O. B. Williams, Agrostologist, Division of Plant Industry, C.S.I.R.O., Deniliquin, identified botanical specimens collected during the survey.

VII. REFERENCES

BUTIER, B. E. (l950).- A theory of prior streams as a causal factor of soil occurrence in the riverine plain of south-eastern Australia. Aust. J. Agric. Res. 1 (3): 231. JOHNSTON, E. J. (1950).- The morphology and evolution of the soils of "Pine Lodge" Estate, New South ·Wales, C.S,I.R.O. Aust. Bull. No. 259. SMITH, R., and JOHNSTON, E. J. (1942).- C.S.I.R. Divisional Report No. 28/42, A reconnaissance soil survey of the Deniboota Domestic and Stock Water Supply and Irri­ gation District, N.S.W. SMITH, R., HERRIOT, R. I., and JOHNSTON, E. J. (1943).- The soil and land-use survey of the Wakool Irrigation District, New South Wales. Coun. Sci. Industr. Res. Aust. Bull. No. 162. 39

APPENDIX I GLCBSARY OF BorANICAL NAMES OF FLORA IN THE DENIBOorA IRRIGATION DISTRICT

C anrnon Name Botanical Name

1. Trees Black box Eucalyptus largiflorens F. Muell. Red gum E. camaldulensis Schnh. Yellow box E. melliodora A. Cunn Grey box E. woollsiana R.T. Baker Ironwood or miljee Acacia oswaldii F. Muell. Boree or myall A. pendula A. Cunn Yarran A. hanalophylla A. Cunn Cooba or native willow A. salicina Lindl. Bull oak Casuarina luehmannii R.T. Baker Murray or white cypress Callitris glauca R. Br. pine Needlewood Hakea leucoptera R. Br. Berrigan or crabapple Pittosporum phillyreoides D.C. Bullock bush or rosewood Heterodendron oleifolium Desf. Tea-tree or moonah Melaleuca pubescens Schauer. Quandong Fusanus acuminatus R. Br.

2. Shrubs Hopbush Dodonaea attenuata A. Cunn Indigo bush or nitre bush Chenopodium nitrariaceum F. Muell. Lignum Meuhlenbeckia cunninghamii ( on creek frontages) F. Muell. Lignum (on plains) · M. coccoloboides J.M. Black Tussock or iron grass Lanandra effusa (Lindl.) Ewart Dillon bush Nitraria schoberi L. Cotton bush Kochia aphylla R. Br. 4-0

3. Grasses Wallaby, white top, or Danthonia semiannularis R. Br. root grass Swamp wallaby grass Amphibranus neesii Steud. Spear or corkscrew grass Stipa variabilis Hughes Windmill grass Chloris truncata R. Br. and C. acicularis Lindl. Rat's-tail fescue Vulpia myuros (L.) Gmel. Cane grass Eragrostis australasica (Steud.) C.E. Hubbard Barley grass Hordeum leporinurn Link . Fairy grass Sporobolus caroli Mez •

4. Miscellaneous Plants Roly poly Bassia quinquecuspis F. Muell. and var. villosa Benth. Prickly saltwort Salsola kali L. (also called roly poly) Reeds Cyperus spp. Rushes Juncus spp. Nardoo Marsilea drurnmondii A. Br. Creeping saltbush Atriplex semibaccata R. Br. Slender-fruited saltbush Atriplex leptocarpa F. Muell. (also called creeping saltbush) Saltweed Kochia ciliata F. Muell. and K. crassiloba R.H. Anderson Marshmallow Malva parviflora L. Poverty weed Calocephalus sonderi F. Muell. Everlasting daisy Helipterum corymbiflorum (white) Schlech . . Everlasting daisy (yellow) Helipterurn variabile Ostenf. Blue crowfoot Erodium cygnorum Nees Burr medic Medicago denticulata Willd. E.J.JOHNSTON PLATE 1 SOILS OF DENIBOOTA IRRIGATION DISTRICT

Fig.1 .- Niemur clay showing relatively bare puffs with white top grass, sane roly poly, and lignum in the crabholes. Black box trees in the background.

Fig.2.- Dillon bush (Nitraria schoberi) on Riverina clay. Ground cover is mainly saltweed (Kochia spp.).

C.S.I.R.u. Aust. Soils Land Use Ser. No.5 E.J.JOHNSTON PLATE 2 SOILS OF DENIBOOTA IRRIGAT ION DISTRICT

Fig.1.- Typical scalded areas on Mundiwa loam. Vegetation in foreground is ma.inly saltweed (Kochia spp.) with sane white top (Danthonia semiannularis).

Fig.2.- Small, treeless plain in southern area • The soil type is T anara 1 oam and the vegetation mainly white top (Danthonia semiannularis) •

C.S.I.R.O. Aust. Soils Land Use Ser. No . 5 E.J.JOHNSTON PLATE 3 SOILS OF DENIBOOTA IRRIGATION DISTRICT

Fig.1 .- View of the contorted surface of Thyra clay. The large crabhole or gilgai is in the foreground. The trees are black box (Eucalyptus largiflorens).

Fig.2.- Typical view of the Murray pine - grey box association on Bunnaloo loam.

C.S.I.R. O. Aust. Soils Land Use Ser. No.5 E.J.JOHNSTON PLATE 4 SOILS OF DENIBOOTA IRRIGATION DISTRICT

Womboota loam carrying grey box, bull oak, and needlewood with white top grass.

C.S.I.R.O. Aust. Soils Land Use Ser. No.5