REPORT TO DEPARTMENT OF NATURAL RESOURCES REGIONAL INFRASTRUCTURE DEVELOPMENT (RID), NORTH REGION ON

An Assessment of Agricultural Potential of Soils in the Gulf Region, North Queensland

Volume 1 February 1999

Peter Wilson (Land Resource Officer, Land Information Management) Seonaid Philip (Senior GIS Technician)

Department of Natural Resources Resource Management GIS Unit Centre for Tropical Agriculture 28 Peters Street, Mareeba Queensland 4880 DNRQ990076

Queensland Government Technical Report

This report is intended to provide information only on the subject under review. There are limitations inherent in land resource studies, such as accuracy in relation to map scale and assumptions regarding socio-economic factors for land evaluation. Before acting on the information conveyed in this report, readers should ensure that they have received adequate professional information and advice specific to their enquiry.

While all care has been taken in the preparation of this report neither the Queensland Government nor its officers or staff accepts any responsibility for any loss or damage that may result from any inaccuracy or omission in the information contained herein.

© State of Queensland 1999

For information about this report contact [email protected] ACKNOWLEDGEMENT

The authors thank the input of staff of the Department of Natural Resources GIS Unit Mareeba. Also that of DNR water resources staff, particularly Mr Jeff Benjamin. Mr Steve Ockerby, Queensland Department of Primary Industries provided invaluable expertise and advice for the development of the agricultural suitability assessment. Mr Phil Bierwirth of the Australian Geological Survey Organisation (AGSO) provided an introduction to and knowledge of Airborne Gamma Spectrometry. Assistance with the interpretation of AGS data was provided through the Department of Natural Resources Enhanced Resource Assessment project. Particular thanks go to Mr Mike Grundy and Mr Ross Searle. CONTENTS

EXECUTIVE SUMMARY

Summary Recommendations

1. PROJECT BRIEF

1.1 Scope 1.2 Location 1.3 Expected Outcomes 1.4 Time Frame

2. BACKGROUND

2.1 Previous Studies

3. METHODS

3.1 Existing Information and Key Area Identification 3.2 Land Systems Interpretation 3.3 Data Base Development 3.4 Airborne Gamma Spectrometry 3.5 Field Verification 3.6 Agricultural Suitability Framework

4. PROJECT FINDINGS

4.1 General Agricultural Suitability Assessment 4.2 AGS Interpretation and Soils Mapping 4.3 Key Area Descriptions – Location & Geomorphology Soil Landscapes Agricultural Suitability 4.4 Soils Types and Soil Landscapes 4.5 Agricultural Suitability Assessment

APPENDICIES

Appendix 1 - Limitations and Suitability Tables Appendix 2 - Soil Type and Soil Landscape Descriptions Appendix 3 - Soil Sample Chemical Analysis and Dispersion Test Results

LIST OF FIGURES

Figure 1: Location of the study area and eleven key areas Figure 2: Description of Leinster Land System showing the complexity of landscape and soil types. (Copied from Galloway et al. 1970) Figure 3: Example of soil limitation and suitability assessment Figure 4: Example of assessment of land system agricultural suitability Figure 5: Airborne Gamma Spectrometry (Courtesy of AGSO) Figure 6: Individual bands of AGS data showing Th, U and K response variation (Courtesy of AGSO)

LIST OF TABLES

Table 1: Potential Crops and Land Use Groups Table 2: Soil Type/Soil Landscape Suitability Classes and Agricultural Land Class Table 3: Area (Ha) of Potential Agricultural Land for each Key Area

ACCOMPANYING MAPS

Map 1: Soil Landscapes of the Mitchell River Area Map 2: Soil Landscapes of the Lynd River, Einasleigh River, Bundock/McKinnons Creek and McBride Plateau Areas Map 3: Soil Landscapes of the Gilbert River Area Map 4: Soil Landscapes of the Flinders River, Upper Cloncurry River and Corella Creek Areas Map 5: Soil Landscapes of the Leichhardt and Alexandra Rivers Area Map 6: Soil Landscapes of the Gregory River Area Map 7: Agricultural Suitability – Tree Crops Map 8: Agricultural Suitability – Bananas Map 9: Agricultural Suitability – Row Crops Map 10: Agricultural Suitability – Field Crops Map 11: Agricultural Suitability – Peanuts Map 12: Agricultural Suitability – Sugar Map 13: Agricultural Suitability – Rice Map 14: An Assessment of Potential Agricultural Suitability from Land Systems Map 15: Regional Interpretation of AGS Data

REFERENCES

EXECUTIVE SUMMARY

Summary

The Gulf Region lacks soils information. Existing land systems data is not at suitable scales for intensive interpretation of agricultural suitability. A general assessment has been made to determine land systems with significant areas of soils with potential for agricultural development.

New data, including airborne gamma spectrometry at regional scales, has been used to further map and assess potential agricultural suitability for eleven key areas. Department of Natural Resources (DNR) staff have identified these key areas for possible irrigation development. Indicative figures of total area of soils with agricultural potential in these key areas are given. These are based on limited field verification and should be considered as preliminary only. Identified potential agricultural soils will require further detailed mapping and assessment work if intensive development is likely to occur.

Recommendations

From this reconnaissance assessment of the agricultural potential of soils in the Gulf Region, the following recommendations are made:

• Further detailed soils and agricultural suitability investigations should be undertaken in the following key areas – The Gilbert River, The Leichhardt River, The Gregory River and the Bundock/McKinnons Creek areas. • Other areas of predominantly red and yellow earths below the western margin of the Eastern Highlands should be further investigated, particularly along the mid reaches of the Einasleigh and Lynd Rivers. • Lands in the Julia Plains and Carpentaria Plains (Flinders River and Upper Cloncurry River areas) should be thoroughly investigated prior to any future irrigation development. This is on the basis of soil chemical limitations and salinity risks. Potential groundwater recharge and discharge should be considered. • Future land resource assessments throughout Queensland should utilise Airborne Gamma Spectrometry data and integrated digital elevation modeling as key mapping tools.

1. PROJECT BRIEF

1.1 Scope

The scope of this project is as stated in the Water Infrastructure Planning and Development Implementation Plan 1997/98 to 2001/02; Definition Statement; Gulf Region Study (Department of Natural Resources, Regional Infrastructure Development, North Region. October 1997).

This study supports the first two phases of that definition statement.

1. Study initiation, collection and review of existing information and study reports. 2. A series of reports dealing with specialised aspects such as land resources and use, hydrology/water management, marketing and cropping systems analysis, engineering, economics, financial, social, cultural and preliminary environmental impacts.

In particular this study provides an updated assessment of the potential suitability of land and soil resources to support regional agricultural development, particularly sustainable irrigation systems in the Gulf Region of North Queensland.

The resulting land resource information will feed into the overall Gulf Region Study to assist the assessment of water resource availability, and potential water requirements within the key areas. Close links have been developed and maintained with the Department of Primary Industries Agronomy and Marketing Groups who are collaborators in the Gulf Region Study.

1.2 Location

The Gulf study area covers the catchments of the Mitchell, Gilbert, Etheridge, Einasleigh, Norman, Flinders, Leichhardt, Albert, Nicholson and Gregory Rivers as defined in the WIP/DIP Gulf Region Study Definition Statement. The area is within the Local Government Shires of Richmond, Burke, Carpentaria, Croydon, Etheridge and Mareeba. The study area lies between the Gulf of Carpentaria and 22o south latitude, and between 138o and 145o east longitude.

More detailed soils investigations were limited to eleven key areas (sections 3.1 and 4.3). The location of the study area and the key areas are shown in Figure 1.

1.3 Expected Outcomes

Within key areas of these catchments, this study has identified the location and quantified the area of land/soil resources which may contribute significantly to irrigation led opportunities for regional development in the Gulf Region of North Queensland.

This may lead to improved sustainable natural resource utilisation and management. Other related strategies include - • State Water Conservation Strategy: A Discussion Paper (1993) • GLADA regional development strategy (in prep) • Gulf Region Landcare strategy (in prep) • Gulf Multiple Use Strategic Plan

1.4 Time Frame

The project commenced in March 1998, following funding approval from RID. Interim results and key area definition were presented in an interim report (June 1998) and have been made available to other Gulf Region study groups to assist with their progress.

Due to time limitations and the extensive area to be surveyed, an assessment commensurate only with a reconnaissance survey was undertaken.

FIGURE 1: Location of the study area and eleven key areas

2. BACKGROUND

2.1 Previous Studies

Previous land resource studies in the region are broad scale and fairly limited in their consideration of agricultural suitability. The majority of previously published information is contained in CSIRO Land Systems reports on the Leichhardt-Gilbert area (Perry et al. 1964) and the Mitchell-Normanby area (Galloway et al. 1970).

The Atlas of Australian Soils (Northcote et al. 1968) provides some broad descriptions of soils and their properties but provides little in the way of analysis for agricultural potential. Some general interpretations of dominant soil attributes for each Principal Profile Form have been made by CSIRO Division of Soils (McKenzie and Hook 1992).

Broad scale soil associations within soil landscape units (1 : 250 000) have been mapped by Grundy and Bryde (1989) for the Einasleigh - Atherton Dry Tropics and suitability for cultivation has been assessed. Only small areas of red and yellow earths are shown as suitable in the Lynd River key area. Reasonably large areas of class 4 suitability land are identified in the McBride Plateau groundwater key area. These areas have been downgraded due to the stony nature of soils. In addition some suitable areas are mapped on the alluvial soils in the upper reaches of the Einasleigh River key area.

A number of other reports provide information on soils of various parts of the study area at varying scales. These include - Webb, Beeston and Hall (1974), Turner and Hughes (1983), Kent and Shepherd (1984), Forster, Gilbert and Passmore (1988), Grundy and Bryde 2 (1989), McKenzie and Hook (1992) and Heiner and Grundy (1994).

3. METHODS

3.1 Existing Information and Key Area Identification

This project aimed to analyse and confirm existing land resource information to determine areas of potential agricultural suitability in the Gulf region.

Eleven key target areas were identified by water resource staff from initial assessment of potential water storage sites throughout the Gulf Region. Key areas were limited to those lands with potential for irrigation development, in close proximity (maximum10km) to major watercourses, to a maximum distance of 60km downstream from potential storage sites. Some additional areas where groundwater or off stream storage potential exists have also been included.

3.2 Land Systems Interpretation

Land system and soils descriptions were analysed to determine potentially arable areas and general agricultural suitability.

Whilst land systems describe the variability of landscape and soil types, their spatial distribution is not defined (due to mapping scale limitations). Each land system description can be quite complex - containing a number of land units that may contain a number of soils in varying proportions (Figure 2). In addition land system descriptions are generalised from observations taken throughout the study area. Thus, specific mapped occurrences of land systems may or may not contain all the described land units and soils in the assigned proportions.

Agricultural suitability is dependent on soil and landscape characteristics which are usually defined at larger scales than land systems mapping. In fact, even in intensive large scale mapping projects (eg 1: 10 000), soil attributes are likely to show considerable variability within particular unique mapping areas. Agricultural suitability based on land systems mapping is at best, a broad generalised indication and extreme care should be taken in using such interpretations. The main outcome is to indicate which land systems have a capacity for more intensive use, and if that were likely to eventuate, would therefore warrant mapping and assessment at larger scales.

Landscape and soil attributes as described in land system reports have been entered into a database and an initial intuitive assessment has been made on their limiting effects on agricultural production. Level 1 has no effect, level 2 has only minor effect, level 3 has a moderate effect and level 4 has a severe effect which precludes agricultural use. The most limiting factor has been used to determine the overall agricultural suitability class for each soil type as high, moderate, low or nil (Figure 3).

FIGURE 2: Description of Leinster Land System showing the complexity of landscape and soil types. (Copied from Galloway et al. 1970)

Soil: Balootha Limitation level

Description Alkaline clay - Colour Dark grey to olive brown - Texture Sandy loam to clay 1 Depth Deep 1 Erosion Nil 1 Drainage Well 1 Mottles Nil 1 Infiltration Slow 2 Runoff Slow 2 Surface cond Hard 2 Subsurf cond Hard 2 Coarse frags Carbonate nodules 2 pH 7-9 Alkaline 3 Salinity hazard Moderate 3 PAWC High 1 Microrelief Moderate gilgai 2 Flooding Nil 1

Est. Ag. Suitability Low

FIGURE 3: Example of soil limitation and suitability assessment

Land system agricultural suitability classes have been determined by considering the described landscape characteristics of the major land units (based on proportional area) and attributes of dominant soils described within those units (Figure 4). Land systems were assigned to one of the following10 suitability classes –

1. Large proportion of the land system area having dominant soils with potentially high agricultural suitability 2. Medium proportion of the land system area having dominant soils with potentially high agricultural suitability 3. Small proportion of the land system area having dominant soils with potentially high agricultural suitability 4. Large proportion of the land system area having dominant soils with potentially moderate agricultural suitability 5. Medium proportion of the land system area having dominant soils with potentially moderate agricultural suitability 6. Small proportion of the land system area having dominant soils with potentially moderate agricultural suitability 7. Large proportion of the land system area having dominant soils with potentially low agricultural suitability 8. Medium proportion of the land system area having dominant soils with potentially low agricultural suitability 9. Small proportion of the land system area having dominant soils with potentially low agricultural suitability 10.Large proportion of the land system area having nil agricultural suitability

Classification terminology has been made deliberately vague due to the nature of land systems that have been assessed on an overall basis rather than for an individual unique occurrence. Thus mapped areas of a particular land system may have a higher or lower agricultural suitability potential than reported here.

Land System : Example

Land Unit Proportion Soil Proportion Ag Suitability

1 Large 1 Dominant High 2 Dominant Moderate 3 Minor Low 2 Medium 1 Dominant High 4 Dominant Low 3 Small 4 Dominant Low 5 Minor Nil

Land system has large and medium areas with dominant soils of high potential agricultural suitability, therefore overall agricultural suitability class is 1

FIGURE 4: Example of assessment of land system agricultural suitability

Only general agricultural suitability has been assessed, as no information relevant to specific cropping or horticultural systems is available at these scales. No climatic data has been considered in agricultural suitability assessment, as the level of effect is dependent on specific land use and crops, particularly in irrigated farming systems.

3.3 Data Base Development

An “Access” data base was developed to record information at various levels, including land system, land unit and soil characteristic. Soil descriptions have been assessed for a number of characteristics likely to affect agricultural production including: texture, depth, slope, erosion, drainage, mottles, sub-surface consistency, coarse fragments, pH, infiltration, run-off, salinity hazard, surface condition, water holding capacity (estimated), micro-relief and flooding. This database has been used to analyse land systems based on their dominant soil types to determine an estimated agricultural suitability.

The data base structure gives the flexibility to record many land units and many soils within each land system. Recording terminology for landscape and soil attributes has been standardised over the two land system reports, which allows a more direct comparison.

3.4 Airborne Gamma Spectrometry

Airborne gamma spectrometry (AGS) (Figure 5) measures gamma radiation emitted from the natural radioactive decay of elements within rocks and soil. The responses of three elements are usually assessed - potassium (K), uranium (U) and thorium (Th), from within approximately the top 30cm of the earths surface. As a result, images which map the spatial distribution of K, U and Th (Figure 6), are produced. Such data have been available for over 30 years and have been utilised particularly in the mining industry. Recent improvements in computer technology, the availability and quality of AGS data have made the use of these data in mapping soils more practical (Tunstall 1998). They can provide information about soil parent materials, soil properties such as surface textures, soil depth, clay types and soil processes such as weathering and leaching.

Broad scale (0.5 - 1.5km line spacing) AGS data was made available for the Gulf Region through collaboration with the Australian Geological Survey Organisation (AGSO), who also has significant expertise in interpretation of AGS data. This AGS data was interpreted to model the spatial representation of soils and soil characteristics that are shown in the maps accompanying this report.

FIGURE 5: Airborne Gamma Spectrometry (courtesy of AGSO)

Potassium Thorium

Uranium Total Count

FIGURE 6: Individual bands of AGS data showing Th, U and K response variation (courtesy of AGSO)

3.5 Field Verification

Field inspection was undertaken to verify the spatial distribution of modelled land and soil resources particularly in defined key areas through visual assessment of soil characteristics.

Limited sampling of soils by hand auger was used to assess their potential suitability for irrigated agriculture and quantify risks to degradation. Characteristics such as salinity hazard, erosion potential, physical conditions, surface crusting and workability were investigated and limited physical and chemical analyses of potential agricultural soils conducted.

Due to time limitations, vehicle access only along major roads and tracks was possible.

3.6 Agricultural Suitability Framework

This chapter outlines the framework used to assess the potential agricultural suitability of the soil types and soil landscape classes described in section 4.3 above.

A number of specific crops/land uses have been identified for the Gulf Region and these have been grouped on the basis of similar soil and management requirements and acceptable limitation ranges (Table 1).

TABLE 1: Potential Crops and Land Use Groups

Tree Bananas Row Field Peanuts Sugar Rice Crops Crops Crops Mangoes Bananas Cotton Navy beans Peanuts Sugar Rice Citrus Maize Melons Sorghum Egg plant Soybeans

Agricultural suitability has been assessed for winter irrigation based production only. This study assumes the use of current agricultural production systems (eg. land preparation, irrigation and harvesting techniques). No specific suitability assessment has been made for individual production variations such as flood, spray or trickle irrigation. The required amount of available water from an irrigation supply system is also assumed.

Rainfall and other climatic factors in the area are subject to considerable annual and shorter-term variability. The four-month wet season (December to March) would probably preclude summer agriculture. Due to the limited information available and the variability over the vast area being studied, no climatic assessment or the potential effects on individual crops has been undertaken in this report. Generally the climate appears suitable for the range of crops assessed. Length of growing season, minimum winter temperatures, maximum summer temperatures, high evaporation rates and rainfall seasonality need to be investigated further.

Similarly, limitations such as flood destruction of infrastructure have not been considered in the agricultural suitability assessment. Further research is required on agricultural systems and methods for winter cropping in wet/dry tropical environments, such as the need for establishment of summer/wet season cover crops and the annual removal of irrigation infrastructure. Some consideration of the effects of summer/wet season conditions has been taken into account in assessing the suitability for perennial crops such as tree cops, bananas and sugar cane.

Given the broad scale reconnaissance nature of this study, and the limited number of field observations, only a general suitability classification has been undertaken. A similar approach has been taken to that of Aldrick and Wilson (1990) in their assessment of a large area of land in the Southern Gulf Region of the Northern Territory. A number of potentially limiting factors has been taken into account. A subjective arbitrary assessment of severity of the effect of these factors on the land use groups has been made due to the relative lack of available information. The limiting factors considered are: soil drainage, plant available water holding capacity, soil physical condition, soil chemical condition, erosion hazard and adverse site factors.

Soil Drainage: This is a consideration of both site related drainage factors, such as runoff and infiltration and internal soil drainage factors such as permeability and waterlogging. It includes assessment of factors such as slope, soil surface textures, and presence of subsoil mottles. Soils have been visually assessed in the range of very poorly to well drained.

Plant Available Water Holding Capacity: This is an assessment of the soils ability to hold and store water and a plants capacity to extract and utilise that water. No quantitative measurements have been made on these soils. Soil chemical conditions such as high pH or sodicidy can significantly reduce soil water availability. Plant available water limitations are reduced by effective well-managed irrigation techniques. Some lighter textured soils may require more frequent irrigation which may have additional management/production cost implications, particularly for less intensively managed broad acre crops. Values for individual soils have been assigned in the range of poor to good.

Soil Physical Condition: A number of factors that effect plant establishment and growth and soil workability have been considered here. They include physical soil attributes such as surface condition (eg. hardsetting, self-mulching, crusting), consistence (degree of soil adhesion and cohesion, hardness of the sub-soil), soil textures, cracking, and effective rooting depth (presence of pans). Severity of effect on individual land use groups has been arbitrarily assigned based on the individual or combined effect of factors. Single or multiple soil physical conditions may be recognised for different soil types.

Soil Chemical Condition: Little is known about soil chemical conditions and associated problems for the individual land use groups assessed. Many of the problems associated with soil chemical conditions can probably be reduced with appropriate management through fertiliser applications, irrigation techniques, crop selection and the like. Chemical factors such as adverse soil pH, toxicity, salinity and sodicity have been considered. Single or multiple factors may influence the level of severity effecting different land use groups. Arbitrary degrees of severity have been assigned to soil type/soil landscape classes, based on the limited chemical information available.

Soil Erosion Hazard: Soil erosion is the most likely (observable) form of land degradation following more intensive agricultural use. It is influenced by a number of factors including climate (in this area, high-intensity seasonal rainfall and cyclonic winds), land management practices and inherent properties of the soil and landforms. Slope, soil textures and soil/site drainage regimes have been used to determine the degree of erosion hazard for each of the land use groups. Low slopes dominate much of the area of this survey, but the extensive length of these makes them susceptible to erosion in many cases. Also, most of the key areas are centred along major streams and alluvial systems that are themselves active and mobile in a geomorphic sense. Accelerated erosion due to human controlled land use influences is common particularly in relatively fragile riverine environments.

Adverse Site Factors: Consideration has been taken of a range of site factors that may effect agricultural production systems. These include but are not limited to, rock outcrop, profile stone and gravel, soil depth, access difficulties, landscape complexity, flooding and inundation.

The degree of severity to which these limitations effect each of the land use groups for each of the described soil types and soil landscape classes is shown in Appendix 1. An overall suitability class for each of the land uses is also shown. This suitability class should not be considered as definitive as only a relatively small number of limitation factors, based on limited information over a large area have been used. Other factors, not considered in this reconnaissance study may have a greater effect and thus alter the suitability for a particular land use. Figures quoted for the area suitable for particular land uses should be considered as indicative only.

4. PROJECT FINDINGS

4.1 General Agricultural Suitability Assessment

Land systems of the Leichhardt-Gilbert (Perry et al. 1964) and Mitchell-Normanby (Galloway et al. 1970) (total area 44,285,000 Ha) were assessed for their potential agricultural suitability as described above. The accompanying Map 14 shows the distribution of general agricultural suitability classes throughout the region.

18 land systems were found to contain significant areas of potentially high agricultural suitability. Total area of these systems is 7,955,000 Ha, representing 18% of the area.

32 land systems were found to contain significant areas of potentially moderate agricultural suitability. Total area of these systems is 21,585,000 Ha, representing 49% of the area.

17 land systems were found to contain significant areas of potentially low agricultural suitability. Total area of these systems is 6,583,000 Ha, representing 15% of the area.

14 land systems were found to contain predominantly areas with nil agricultural suitability. Total area of these systems is 8,162,000 Ha, representing 18% of the area.

Extreme caution is required when using these figures to determine total areas of suitable agricultural land due to the complexities of land systems mapping discussed above.

4.2 AGS Interpretation and Soils Mapping

Initial interpretation has used land system concept models to stratify and classify AGS data. Thorium and Potassium signal values were used to determine unique combinations for the dominant land systems described in the area. This process has allowed definition of broad landscape types and shows some spatial relationships between land systems (MAP 15).

AGS combinations were used to define major geological variations between systems, particularly in upland erosional areas where AGS signals are dominated by exposed country rock. AGS variations within the McBride Plateau basalts, between Mount Garnet and The Lynd, may represent differences in basalt flows which are hard to map using conventional methods. These differences have significance in assessing soil nutrient status, which may vary with particular basalt flow parent materials.

Depositional and outwash plains in the lower Gulf landscape and major sediment sources for some alluvial systems, were also differentiated by AGS combinations. In these areas soil type and pedogenetic processes tend to dominate AGS signals. Variations often reflect parent materials, soil textures and to some extent, temporal variations caused by processes such as leaching.

Some anomalies with the land system mapping were identified, particularly in extensive old alluvial systems. In some instances this was particularly noticeable around the extremities of land system study areas where differences with adjoining mapping also occurs. It is believed that some of these anomalies represent wrongly mapped areas possibly due to limited field verification or small areas within surveys which may have been lumped with other land systems for convenience.

AGS has been particularly useful for providing a reasonably complete data set over the region such that similarities between landscapes can be identified. For example, an area on the northern boundary of the Leichhardt-Gilbert report, mapped as Mayvale land system, is believed to have greater affinities with the Leinster land system of the Mitchell- Normanby project which adjoins it.

Some areas of Balurga land system in the north west of the Mitchell-Normanby report show variation in AGS signals to similarly mapped occurrences of Balurga land system in the central portion of the study. More detailed soils investigation during the CYPLUS study (Biggs & Philip 1995) have revealed differences in these two areas - the central section being dominated by deep gradational massive red soils (Kimba) and the north west area being deep massive nodular yellow soils (Clark).

Some spatial variations within mapped land systems boundaries have also been identified with AGS, although this is limited somewhat by the resolution of the source data. An example of this, is the definition of some smaller drainage features throughout occurrences of Dunbar land system in the south west of the Mitchell-Normanby report. These variations show closer affinity in AGS signals to the coarser textured recent alluviums of Radnor and Cumbulla land system which have their source in the granitic uplands to the east. These areas probably equate to the described but unmapped land unit 1 of the Dunbar land system.

Further interpretation of AGS surfaces for each of the key areas has been undertaken to determine variations within more confined geographic boundaries. This was to eliminate anomalous classification of AGS signal groups which may be related to other features within the larger Gulf study area. Each of the eleven identified key areas is discussed below.

4.3 Key Area Descriptions

1. THE MITCHELL RIVER AREA (MAP 1)

Location and Geomorphology

This area is located in the central reaches of the Mitchell River, approximately 100km north west of Chillagoe. It extends from the potential dam site, near Groganville, west to approximately the junction with the Lynd River. The Walsh River joins the Mitchell River at about the centre of this study area.

The eastern portion of the area is in elevated, undulating to hilly country on mostly metamorphosed sediments, greywackes and some volcanics. Some of this area is on old marine sediments of the Hodgkinson formation. The study area is split in the eastern quarter by the Palmerville Fault, to the west of which the Mitchell River floodplain widens.

The western section of the study area lies within the extensive low level plains that surround the Gulf of Carpentaria. These plains consist mainly of weathered terrestrial deposits which were laid down in Tertiary times and are slightly dissected in most areas by shallow valleys (Galloway et al. 1970).

Soil Landscapes

The rocky uplands in the east of this study area show little in the way of soil development and were not investigated further. Potential soils suitable for agricultural development are mostly confined to the western lowland portions of the study area. These are mainly cracking grey clays, yellow and grey podzolics and some areas of moderately deep red earthy sands.

Sandy red and yellow earths (Pit and Mundy soils) occur on slightly elevated plains and low rises at the northern and southern extremities of the study area. These are representatives of the Balurga and Kimba land systems of Galloway et al. (1970). Slopes are commonly 0-2 % and up to 8-10 %. These are remnant plains formed from erosion of Tertiary sandstones and sediments.

Yellow and grey podzolic texture contrast soils (Bierwirth) have formed on the undulating lowlands through which the Mitchell River flows. These are mostly on old stable alluvial deposits described as the Leinster and Radnor land systems by Galloway et al. (1970).

In lower landscape positions and on active floodplain deposits, cracking clays are dominant (Koolatah). Cracking brown clays (Wrotham) are formed in situ on weathered shales (Maple land system) in areas of gentle to moderate slope.

Agricultural Suitability

The area has a low to moderate potential for agricultural development. The most suitable soils are the red and yellow earths (Pit and Mundy) and the cracking brown clays (Wrotham) all of which occur at considerable distance from the main river channel. The grey clays (Koolatah) and podzolics (Bierwirth) occur in significant quantity but have moderate limitations due to potential salinity, sodicity, erodibiility, poor drainage and low wet season trafficability.

2. THE LYND RIVER AREA (MAP 2)

Location and Geomorphology

This study area is in the upper catchment of the Lynd River, approximately 80km southwest of Chillagoe. The southern extremity is on the lower edges of the McBride Plateau, and extensive basalt flow (see area 4 below). The main part of the study area lies within undulating to rolling low hills of mostly metamorphic and granitic rocks.

In the west the study site extends to the inland extremity of the Gulf plains, an area of moderately deep red and yellow sandy soils. This is a depositional plain formed from eroded out-wash sediments from sandstone, metamorphic and granitic parent materials of the Great Divide to the east.

Soil Landscapes

Shallow gravelly and yellow-brown texture contrast soils dominate much of the study area. These have formed on the hilly to undulating areas of granitic (HG, RG and UG) metamorphic (HM, RM and UM) and Tertiary deposits (HT, RT and UT) rocks. Similar soils showing slightly more profile development occur on gently undulating (PG, PM, PT and PB) plains mostly within the southern portion of the area.

Minor areas of alluvial soils occur within close proximity to the main river channels. These are sodic soils, yellow earths, cracking grey clays and solodic soils. Very minor areas of black earths occur in low-lying areas on the edge of the McBride Plateau, in the southern portion of the area. These are stony in places.

Agricultural Suitability

The area generally has a low potential agricultural suitability due to the shallow nature of soils and undulating to rolling and hilly landscapes. Some of the alluvial and plains areas are more encouraging from a landscape perspective but have relatively poor agricultural soils and are susceptible to erosion.

3. THE EINASLEIGH / COPPERFIELD RIVER AREA (MAP 2)

Location and Geomorphology

This area extends north along the Copperfield River from near the Kidston gold mine dam site to the junction of the Einasleigh River at the township of Einasleigh. From here it extends approximately a further 70km to the northwest along the Einasleigh River.

The southern section of the area, along the Copperfield River, is mostly undulating to rolling rises of granite and metamorphic rocks, with associated shallow sandy red and yellow earths and duplex soils. Around the Einasleigh township an influence of basalt from the McBride Plateau (to the east) exists, with resultant areas of rocky grey clayey soils.

The Einasleigh River continues to flow northwest through undulating granitic country until almost the northern extremity of the study area. Here it enters the western plains and some floodplain development occurs with associated brown sandy alluvial soils.

Soil Landscapes

The majority of the area, particularly in the south, has shallow gravelly soils of little consequence (HG, RG, HM, RM, HT, RT, HB and RB). Red and yellow podzolic soils and earths have developed on low plains of metamorphic parent materials (PM) in the central section of the area to the north of Einasleigh township. Some smaller plains with black earths and grey clays formed on basaltic parent material (PB) also occur at this location.

Alluvial soils have developed where alluvial plains have not been overly confined by surrounding uplands country. Grey clays, black earths, sodic soils and some yellow earths (AG, AB, AM) occur in the areas immediately upstream and downstream of Einasleigh along the Einasleigh River and Copperfield Creek. Significant amounts of podzolics and red and yellow earths (AM) occur in the northern portion of the area.

Agricultural Suitability

The area generally has a low to moderate agricultural suitability. Significant soils are the podzolics and red and yellow earths (AM) and the grey clays and black earths (AB) found along major river channels. These have significant limitations due to landscape position and drainage characteristics. A potential salinity risk may exist in some locations. Many of the flatter plains may appear inviting but significant rock may prove these to be unsuitable. Further investigation is being undertaken in this area, particularly to the north of the Einasleigh township (Enderlin, in prep.).

4. THE McBRIDE PLATEAU AREA (MAP 2)

Location and Geomorphology

The McBride Plateau, located approximately 50 km south of Mount Garnet, consists of a large area (10 000 km2) of basalt flows. The axis of the Plateau straddles the north-south ridge of the Great Dividing Range.

Successive basalt flows were laid down in the Late Tertiary-Quaternary during a period of spasmodic vulcanicity (Twidale 1966). Significant periods of weathering and denudation between flows are evident, with at least three distinct basalts being recognised. Variation of soil nutrients between areas on different flows is locally recognised through variation in pasture grass nutrition (John Boorman DPI, pers. comm.).

Twidale (1966) described the Plateau as essentially “ a great topographic and structural dome…(which) comprises a series of stepped plains separated by scarps (commonly 5 to 10 metres high) which are the consolidated fronts of lava flows. The lava plains are uneven, with low stony ridges or rises, some exhibiting collapse structures…”

Soil Landscapes

The basaltic parent materials largely influence soils on the McBride Plateau. They are predominantly red earths, kraznozems and euchrozems (PB) and have varying amounts of rock. Smaller areas of sodic soils, podzolics and yellow earths occur on areas of granitic and metamorphic parent materials (UG, PG, UM and PM) particularly at the edges of the Plateau and as small patches within.

Agricultural Suitability

The area generally has a moderate agricultural potential. The main limitation appears to be the rockiness of soils, which is difficult to detect and map. Tree crops and other systems not requiring intensive cultivation practices may be best suited to the area.

5. THE BUNDOCK AND McKINNONS CREEKS AREA (MAP 2)

Location and Geomorphology

This area is located in the upper reaches of the Einasleigh River catchment, approximately 80 km to the southeast of the Einasleigh township. The area is predominantly rugged to undulating hills of mainly granite, metamorphic and some igneous rocks.

Broad alluvial plains (up to 5km wide) have developed in places around the Einasleigh River and McKinnons Creek. These are relatively flat, low lying areas where some seasonal flooding would be likely to occur. Soil Landscapes

The rocky upland areas have little in the way of well developed soils. They are mainly shallow, sandy and gravelly (HG, HM, HB, HT). Significant areas of mainly black earths and cracking clays have developed on the broad alluvial plains and reflect a variety of basaltic and metamorphic parent materials (AB, AM). Granitic influences in some areas have resulted in some minor solodic and texture contrast soils (AG).

Agricultural Suitability

The area generally has a moderate to good agricultural potential based on the expanse of alluvial soils. Major limitations relate to drainage characteristics, seasonal flooding and waterlogging and the possibility of a salinity risk.

6. THE GILBERT RIVER AREA (MAP 3)

Location and Geomorphology

The Gilbert River area is located approximately 40 km to the West of Georgetown. It extends from the North Head dam site, 20km south of the Robertson River junction, north and then northwest along the Gilbert River.

The upper portion of the area is elevated, rolling low hills and plains formed mainly on sandstone, deeply weathered meta-sediments and rhyolitic igneous rocks. There is little influence from the Georgetown granites that occur to the northeast.

In about the centre of the area (near the Pillars, a pair of low hills of outcropping granite), the Gilbert River turns to the northwest to flow towards the Gulf of Carpentaria. The alluvial plain broadens somewhat from this location although it is restricted to a width of approximately 10km due to slightly elevated sandstone and tertiary sediments on both sides of the river.

Soil Landscapes

The upper half of the study area is rolling to undulating rises and plains. Most of the soils are shallow and rocky. Minor areas of red and yellow earths, solodics and red and grey clays occur on mostly metamorphosed parent materials. Few areas of major agricultural significance were observed in this portion of the area. Alluvial deposits along the Gilbert River are elevated, narrow and erodible.

In the lower half of the study area a number of soils with agricultural potential exist. On the northern side of the river, significant areas of deep sandy red and yellow earths (Pit, Mundy and Searly) occur on elevated plains. These have developed on Tertiary sedimentary deposits and outwash plains formed from erosion of the Bythesdale and Rolling Downs Sandstones which outcrop in the Gregory Range to the south. Small plateau remnants of a higher lateritised Tertiary surface occur throughout this area (RT). These have shallow brown sands and significant lateritic gravels and hardpans.

Recent alluvial deposits along the Gilbert River appear related mainly to the rhyolitic and granitic parent materials found in the upper part of the study area. These alluvial soils (Mills) are fine grained (silty) and micaceous and form relatively broad low levees to a distance of about 2km from the river. Lower lying backplains and floodouts dissect these levees. They have poorly drained clayey soils and appear frequently inundated. Undulating plains have developed yellow podzolic soils (Bierwirth).The bed load of the Gilbert River is mainly coarse sand.

Agricultural Suitability

The Gilbert River area generally has a good potential for agricultural development. The alluvial soils (Mills) and earths (Mundy, Searly and Pit) appear to be best suited. They are located close to the main river channel and have few limitations other than those associated with their landscape position. The yellow podzolics are less suited due to their susceptibility to erosion and sodic sub soils.

7. THE FLINDERS RIVER AREA (MAP 4)

Location and Geomorphology

This is an extensive area stretching along the Flinders River from Richmond in the south to near Normanton on the Gulf of Carpentaria in the north. It includes sections along the Cloncurry River in the west and the Saxby River in the east.

The study area is within the broad Carpentaria Plain, as described by Twidale (1966). The Carpentaria Plain was formed by Mesozoic subsidence and is floored by Cretaceous rocks and sediments (mainly sandstones). These sandstones and similar sandy Tertiary deposits form the parent material of the broad sandy Claraville Plain to the east.

Erosion of soft shales, limestones and greywacke of the Cretaceous Rolling Downs Group to the south has lead to the formation of low relief undulating rises in that area (the Julia Plains). Deposition of this silty material in the central reaches of the Flinders and Cloncurry Rivers (on the Wondoola Plain) has resulted in a vast monotonously flat plain of grey and brown cracking clays (reportedly only 2 – 3 metres thick and overlying sandy deposits). An outstanding feature of these silts and the derived soils is their uniformity.

With the exception of the major rivers, drainage lines in the area are broad shallow depressions, many of which drain to closed depressions. Due to the prevalent low gradients and except in the vicinity of major steams, the area is generally poorly drained.

Soil Landscapes

Grey and brown clays (Blakens) derived from fine-grained Rolling Downs marine deposits cover the great majority of this area. They have been mapped on the basis of their geomorphology as (1) those derived in situ (Blakens sedentary) (2) those deposited by ancient/mostly relict alluvial systems (Blakens old) and (3) those deposited by current mostly active stream channels and fluvial systems (Blakens active). These have been mapped primarily through their differences in radiometric signals, though little variation in soil morphology was observed in the field. Duration, frequency and depth of annual flooding events between these areas may reflect minor differences in suitability for some agricultural systems.

Some significant areas of coarse sandy soils (Cockatoo) occur in the east of the area and in particular in the headwaters of the Saxby River. These soils are broad outwash plains from the erosion of Tertiary deposits and sandstones of the Eastern Highlands. Minor areas of yellow and brown earths (Willow) have developed on highly weathered remnants of Tertiary deposits that reputedly underlay the clay plains.

Agricultural Suitability

The area generally has a low potential for agricultural development. This primarily reflects the vast clay plains that have limitations due to poor drainage characteristics, low wet season trafficability, soil chemical conditions including high pH, sodicity and a relatively high risk to salinity. Some of the slightly elevated earthy areas (Willow) may have a reasonable agricultural potential though these are relatively small in area.

8. THE UPPER CLONCURRY RIVER AREA (MAP 4)

Location and Geomorphology

This area is located in the upper reaches of the Cloncurry River, from near the township of Cloncurry northeast to the junction of the Flinders River and the area (7.) described above.

The headwaters of the Cloncurry River are in the metamorhosed and igneous rocky hills of the western highlands. The main part of the study area, to the north of Cloncurry, lies within the western portion of the Julia Plain. This is mainly rolling to undulating rises of cracking clay soils formed on the Rolling Downs Group fine- grained sediments.

Narrow alluvial plains of fine-grained brown and red soils occur in close proximity to the river. These are recent deposits sourced from the rocky hills to the south.

Soil Landscapes

The majority of the area is covered by the Blakens grey and brown clays discussed for the Flinders River area above. Other significant areas of darker yellowish to olive brown clays (Minty) have also been mapped. These are also formed from fine-grained Rolling Downs marine sediments and have been distinguished by their radiometrics pattern.

Some areas of brown (Price) and red (Zingari) earthy soils occur along major water courses. These have developed from a range of alluvial and colluvial material derived from sedimentary, metamorphic and igneous rocks which occur in the upper catchment. Agricultural Suitability

The area generally has a low potential for agricultural development based, as for area 7 above, on the dominance of clay soils derived from Rolling Downs marine sediments. The earthy alluvial and colluvial soils show more promise although they have a minor extent here.

9. THE CORELLA CREEK AREA (MAP 4)

Location and Geomorphology

This area is located along Corella Creek, approximately 40 km to the west of Cloncurry.

The area is mainly rocky hills and undulating rises within the western highlands. It is mostly sediments, metamorphic and igneous rocks with associated shallow red and yellow earths and skeletal sands. The lower portion of the area enters the southwestern extremity of the Julia Plain (as discussed in 7. and 8. above) with associated clay and alluvial soils.

Soil Landscapes

Soils in the upper portion of this area are generally shallow and gravelly with little profile development. Clay soils (Blakens and Minty) and minor earths (Price) as described for the Upper Cloncurry River area (8 above) occur in the lower portion of the area.

Agricultural Suitability

The area generally has a low potential for agricultural development on the lowland clay soils as discussed elsewhere. Very minor areas of earthy soils would not warrant major development.

10. THE LEICHHARDT AND ALEXANDRA RIVERS AREA (MAP 5)

Location and Geomorphology

This area is located approximately 150 km north-northwest of Cloncurry.

Much of the area is within the northwestern extremity of the Julia Plain (discussed in 7. above) and appears as a flat to very gently undulating plain. In the north and east of the area, remnant hills and uplands of Tertiary deposits occur. These are reported to be contiguous with deposits to the east of the Flinders River and their downwarping has led to the infilling of lower areas with clays of the vastly flat Wondoola Plain.

Soil Landscapes

Low lying areas of brown and grey cracking clay soils (Blakens) dominate. Relatively large areas of brown and red earthy alluvial soils (Price) have formed as levee deposits along the Leichhardt River. These have their source in the sediments, metamorphics and igneous rocky hills of the western highlands to the south.

Rocky upland areas of Tertiary deposits in the north have shallow sandy soils as do the hilly upland sandstone areas in the upper catchment to the south.

Agricultural Suitability

The area generally has a low to moderate agricultural suitability. As discussed previously, the clays have significant limitations. This area does however contain a quantity of potentially arable earthy alluvial and colluvial soils that may warrant further investigation. Potential limitations exist due to their landscape position and hard setting surfaces, particularly under continued cultivation.

11. THE GREGORY RIVER AREA (MAP 6)

Location and Geomorphology

This area is located along the mid-reaches of the Gregory River, to the southwest of Gregory Downs homestead.

The southern portion of this study area is within the rocky foothills of the western highlands. Sandstones, metamorphics and igneous rocks predominate with localised areas of limestone. Here the Gregory River is confined to a narrow valley, but in the lower third of the area the river flows through a much broader plain. This is the northwestern extremity of the Wondoola Plain (discussed in 7. above).

Soil Landscapes

Silty brown and grey clays formed from fine-grained sediments of the Rolling Downs Group predominate in the lowland areas. Moderate areas of calcareous red earths (Tilly) have developed in close proximity of the river, particularly to the north of Gregory Downs. In other areas these have developed on sedimentary deposits and are of poorer quality (Tilly shallow).

Agricultural Suitability

The area generally has a moderate to low agricultural suitability due to the dominance of shallow rocky soils or Blakens clays discussed above. Some of the red earthy soils (Tilly) described here are of high agricultural potential but further work is required to define their spatial extent.

4.4 Soil and Soil Landscape Descriptions

Fieldwork was undertaken during 1998 throughout most of the study areas. A total of 60 site descriptions were completed and ten broad soil types have been described. Soils with minor spatial extent or those with little potential for irrigated agriculture have not been considered further. Full descriptions of potential agricultural soils are given in Appendix 2 with limited chemical data in Appendix 3.

Four soil descriptions have been adopted directly from the land systems reports of Perry et al. (1964) and Galloway et al. (1970). These occur in areas where access or time did not permit further investigation during field visits.

Very limited field work and site descriptions were undertaken in the Bundock/McKinnons Creeks, Einasleigh River, Lynd River and McBride Plateau areas due to a lack of time, the onset of the wet season and the fact that previous more intensive studies have been undertaken in most of these areas (Grundy and Bryde 1989). As such, soil descriptions are limited to estimates of soil types and associations based on landscape position and parent materials, previous studies and mapping, geological information and current investigations being undertaken in the Einasleigh area (Enderlin in prep.). Probable limitations have been assigned to the soil landscape classes for assessment of land use suitability. These should be considered as generalised estimates only and further more detailed investigations should be undertaken in potential agricultural development areas.

4.5 Agricultural Suitability Assessment

Individual soil types and soil landscape classes have been assessed for their potential suitability for agricultural development for the range of defined crop/land use groups (Section 4.2 and Appendix 1).

Suitability classes are:

Class 1 – Suitable with nil to minor limitations Class 2 – Suitable with moderate limitations Class 3 – Unsuitable

The following Table 2 shows the suitability class of each soil type/soil landscape for each crop/land use group. It also gives an overall agricultural land class for each soil based on the range of crop/land use groups for which it is suitable. This rating gives an overall assessment of potential for development, since a soil suitable for growing only one crop type, cannot be considered as productive as a soil which could grow a wider range of crops.

Agricultural land classes are:

A1 – Suitable for a wide range of assessed crop/land use groups A2 – Suitable for a narrow range of assessed crop/land use groups C – Not considered suitable for any of the assessed crop/land use groups

Table 3 gives the area (hectares) of each agricultural land class within five and ten kilometres of the main river channel for each key area. It also gives the total area of potential agricultural land and this figure expressed as a percentage of the total of the key area. These areas are indicative only. Due to variations within mapped units and land management requirements the effective agricultural land may be up to 30% less than reported here. Maps 7(a,b) to 13(a,b) show the spatial extent of potential agricultural lands for each of the crop/land use groups.

TABLE 2: Soil Type/Soil Landscape Suitability Classes and Agricultural Land Class

Soil / Soil Suitability Class (see Appendix 1) Agricultural Landscape Tree Bananas Row Field Peanut Sugar Rice Land Class Blakens 3 3 3 3 3 3 2 A2 Bierwirth 1 1 1 1 1 2 3 A1 Mundy 1 1 1 1 1 1 3 A1 Mills 2 2 1 1 1 2 3 A1 Minty 3 3 3 3 3 3 2 A2 Price 2 2 1 1 1 2 3 A1 Pit 1 1 1 1 1 1 3 A1 Searly 1 1 1 1 1 1 3 A1 Tilly 1 1 1 1 1 1 3 A1 Willow 1 1 1 1 1 1 3 A1 Cockatoo 2 2 2 2 2 2 3 A1 Zingari 1 1 1 1 1 1 3 A1 Koolatah 3 3 2 3 3 3 2 A2 Wrotham 2 2 2 2 3 2 2 A2 UG 3 3 3 3 3 3 3 C PG 2 2 2 2 2 2 3 A1 AG 3 3 2 2 2 3 3 A2 UM 2 2 3 3 3 2 3 A2 PM 2 2 2 2 2 2 3 A1 AM 2 2 2 2 2 2 3 A1 UB 1 2 3 3 3 3 3 A2 PB 1 2 2 2 2 3 3 A1 AB 2 2 2 2 3 3 2 A1 UT 1 2 1 1 2 2 3 A1 PT 1 1 1 1 1 1 3 A1 AT 2 2 1 1 1 2 3 A1

TABLE 3: Area (Ha) of Potential Agricultural Land for each Key Area

Key Area Total Area Area of Ag. Land Class Area of Ag. Land Class A2 Potential Ag. Land (Ha) A1 (Ha) (Ha) Within 5 km Within 5-10 Within 5 km of Within 5-10 Area (Ha) % of Total Area of river km of river river km of river Mitchell River 263 000 24 900 50 500 70 600 21 500 167 500 60 %

Lynd 240 000 16 400 16 000 17 800 3 600 39 400 15 % River Einasleigh/ 469 000 61 500 30 400 47 000 22 000 160 900 35 % Copperfield McBride Plateau 449 600 300 600 35 000 335 600 75 %

Bundock/ 291 000 48 900 12 200 53 300 17 300 131 700 45 % McKinnons Gilbert River 295 000 51 900 30 900 0 0 88 800 30 %

Flinders River 1 859 000 118 200 107 600 928 000 646 000 1 799 800 95 %

Cloncurry River 293 500 15 100 12 700 153 200 112 500 293 500 100 %

Corella Creek 209 000 18 200 5 200 31 400 32 500 87 300 40 %

Leichhardt/ 695 000 79 700 47 800 253 700 190 600 571 800 80 % Alexandra Gregory River 146 000 17 700 16 800 25 700 12 400 72 600 50 %

APPENDIX 1 Limitations and Suitability – TREE CROPS (mangoes, citrus) Degree of severity of limitation – 1 = nil or minor, 2 = moderate, 3 = high (severe) Suitability Class – 1 = suitable with nil to minor limitations, 2 = suitable with moderate limitations, 3 = unsuitable Soil / Soil Soil Drainage Plant Avail. Soil Physical Soil Chemical Soil Erosion Adverse Site SUITABILITY Landscape Water Condition Condition Hazard Factors CLASS (1-3) Blakens 3 (f,w) 1 2 (c,h) 2 (s,p,d) 1 3 (t) 3 Bierwirth 1 (w) 1 1 1 1 1 1 Mundy 1 1 1 1 1 1 1 Mills 2 (f) 1 1 1 1 2 (t) 2 Minty 3 (f) 1 2 (c,h) 2 (s,p,d) 1 3 (t) 3 Price 1 1 1 1 1 (b) 2 (t) 2 Pit 1 1 1 1 1 1 1 Searly 1 1 1 1 1 1 1 Tilly 1 1 1 1 1 1 1 Willow 1 1 1 1 (p) 1 (b) 1 1 Cockatoo 1 1 2 2 (t) 1 1 1 2 Zingari 1 1 1 1 1 1 1 1 Koolatah 2 3 (f,w) 1 2 (h) 2 (s,p) 1 3 (t) 3 Wrotham 2 2 (w) 1 2 (c) 2 (p) 1 2 (t,r) 2 UG 2 (w) 1 2 (h) 2 (d) 2 3 (r,t,d) 3 PG 2 (w) 1 2 (h) 2 (d) 1 2 (t) 2 AG 2 (f,w) 1 2 (h) 2 (d) 1 3 (t) 3 UM 1 1 1 1 1 2 (l,d) 2 PM 1 1 1 2 (d) 1 2 (t) 2 AM 2 (f) 1 1 2 (d) 1 2 (t) 2 UB 1 1 1 1 1 1 (r,l) 1 PB 1 1 1 1 1 1 (r) 1 AB 2 (f,w) 1 1 2 (s) 1 2 (t) 2 UT 1 1 1 1 1 1 (r,l) 1 PT 1 1 1 1 1 1 1 AT 2 (f) 1 1 1 1 2 (t) 2 Limitations and Suitability – BANANAS Degree of severity of limitation – 1 = nil or minor, 2 = moderate, 3 = high (severe) Suitability Class – 1 = suitable with nil to minor limitations, 2 = suitable with moderate limitations, 3 = unsuitable Soil / Soil Soil Drainage Plant Avail. Soil Physical Soil Chemical Soil Erosion Adverse Site SUITABILITY Landscape Water Condition Condition Hazard Factors CLASS (1-3) Blakens 2 (f,w) 1 2 (c,h) 2 (s,p,d) 2 (a) 3 (t) 3 Bierwirth 1 (w) 1 1 1 1 1 1 Mundy 1 1 1 1 1 1 1 Mills 2 (f) 1 1 1 1 2 (t) 2 Minty 2 (f) 1 2 (c,h) 2 (s,p,d) 2 (a) 3 (t) 3 Price 1 1 1 1 1 (b) 2 (t) 2 Pit 1 1 1 1 1 1 1 Searly 1 1 1 1 1 1 1 Tilly 1 1 1 1 1 1 1 Willow 1 1 1 1 (p) 1 (b) 1 1 Cockatoo 1 1 2 2 (t) 1 1 1 2 Zingari 1 1 1 1 1 1 1 1 Koolatah 2 3 (f,w) 1 2 (h) 2 (s,p) 1 3 (t) 3 Wrotham 2 2 (w) 1 2 (c) 2 (p) 1 2 (t,r) 2 UG 1 1 2 (h) 2 (d) 2 3 (r,t,d) 3 PG 1 1 2 (h) 2 (d) 1 2 (t) 2 AG 2 (f) 1 2 (h) 2 (d) 1 3 (t) 3 UM 1 1 1 1 1 2 (l,d) 2 PM 1 1 1 2 (d) 1 2 (t) 2 AM 2 (f) 1 1 2 (d) 1 2 (t) 2 UB 1 1 1 1 1 2 (r,l) 1 PB 1 1 1 1 1 2 (r) 1 AB 2 (f) 1 1 2 (s) 1 2 (t) 2 UT 1 1 1 1 1 2 (r,l) 1 PT 1 1 1 1 1 1 1 AT 2 (f) 1 1 1 1 2 (t) 2 Limitations and Suitability – ROW CROPS (cotton, maize, sorghum, soybeans) Degree of severity of limitation – 1 = nil or minor, 2 = moderate, 3 = high (severe) Suitability Class – 1 = suitable with nil to minor limitations, 2 = suitable with moderate limitations, 3 = unsuitable Soil / Soil Soil Drainage Plant Avail. Soil Physical Soil Chemical Soil Erosion Adverse Site SUITABILITY Landscape Water Condition Condition Hazard Factors CLASS (1-3) Blakens 1 1 2 (c,s) 3 (s,p,d) 2 (a) 1 (w) 3 Bierwirth 1 1 1 (g) 1 1 (b) 1 1 Mundy 1 1 1 1 1 1 1 Mills 1 1 1 1 1 (b) 1 1 Minty 1 1 2 (c,s) 3 (s,p,d) 2 (a) 1 (w) 3 Price 1 1 1 1 1 (b) 1 1 Pit 1 1 1 1 1 1 1 Searly 1 1 1 1 1 1 1 Tilly 1 1 1 1 1 1 1 Willow 1 1 1 1 (p) 1 (b) 1 1 Cockatoo 1 1 2 2 (t) 1 1 1 2 Zingari 1 1 1 1 1 1 1 1 Koolatah 2 1 1 2 (c,s) 2 (s,p) 1 1 (w) 2 Wrotham 2 1 1 2 (c,s) 2 (p) 2 (b) 2 (w,r) 2 UG 1 1 2 (g,s) 2 (d) 3 (c) 3 (r) 3 PG 1 1 2 (g,s) 2 (d) 2 (b) 1 2 AG 1 1 2 (s) 2 (d) 2 (a) 1 2 UM 1 1 2 (g,s) 1 3 (c) 3 (r) 3 PM 1 1 2 (g,s) 2 (d) 2 (b) 1 2 AM 1 1 2 (s) 2 (d) 2 (a) 1 2 UB 1 1 1 1 1 3 (r) 3 PB 1 1 1 1 1 2 (r) 2 AB 1 1 1 2 (s) 1 1 2 UT 1 1 1 1 1 1 (r) 1 PT 1 1 1 1 1 1 1 AT 1 1 1 1 1 1 1

Limitations and Suitability – FIELD CROPS (navy beans, melons, egg plant) Degree of severity of limitation – 1 = nil or minor, 2 = moderate, 3 = high (severe) Suitability Class – 1 = suitable with nil to minor limitations, 2 = suitable with moderate limitations, 3 = unsuitable Soil / Soil Soil Drainage Plant Avail. Soil Physical Soil Chemical Soil Erosion Adverse Site SUITABILITY Landscape Water Condition Condition Hazard Factors CLASS (1-3) Blakens 1 1 2 (c,s) 3 (s,p,d) 2 (a) 3 (w) 3 Bierwirth 1 1 1 (g) 1 1 (b) 1 1 Mundy 1 1 1 1 1 1 1 Mills 1 1 1 1 1 (b) 1 1 Minty 1 1 2 (c,s) 3 (s,p,d) 2 (a) 3 (w) 3 Price 1 1 1 1 1 (b) 1 1 Pit 1 1 1 1 1 1 1 Searly 1 1 1 1 1 1 1 Tilly 1 1 1 1 1 1 1 Willow 1 1 1 1 (p) 1 (b) 1 1 Cockatoo 1 1 2 2 (t) 1 1 1 2 Zingari 1 1 1 1 1 1 1 1 Koolatah 2 1 1 2 (c,s) 2 (s,p) 1 3 (w) 3 Wrotham 2 1 1 2 (c,s) 2 (p) 2 (b) 2 (w,r) 2 UG 1 1 2 (g,s) 2 (d) 3 (c) 3 (r) 3 PG 1 1 2 (g,s) 2 (d) 2 (b) 1 2 AG 1 1 2 (s) 2 (d) 2 (a) 1 2 UM 1 1 2 (g,s) 1 3 (c) 3 (r) 3 PM 1 1 2 (g,s) 2 (d) 2 (b) 1 2 AM 1 1 2 (s) 2 (d) 2 (a) 1 2 UB 1 1 1 1 1 3 (r) 3 PB 1 1 1 1 1 2 (r) 2 AB 1 1 1 2 (s) 1 1 2 UT 1 1 1 1 1 1 (r) 1 PT 1 1 1 1 1 1 1 AT 1 1 1 1 1 1 1

Limitations and Suitability – PEANUTS Degree of severity of limitation – 1 = nil or minor, 2 = moderate, 3 = high (severe) Suitability Class – 1 = suitable with nil to minor limitations, 2 = suitable with moderate limitations, 3 = unsuitable Soil / Soil Soil Drainage Plant Avail. Soil Physical Soil Chemical Soil Erosion Adverse Site SUITABILITY Landscape Water Condition Condition Hazard Factors CLASS (1-3) Blakens 1 1 3 (c,s,t) 2 (s,p,d) 2 (a) 2 (w) 3 Bierwirth 1 1 1 (g) 1 1 (b) 1 1 Mundy 1 1 1 1 1 1 1 Mills 1 1 1 1 1 (b) 1 1 Minty 1 1 3 (c,s,t) 2 (s,p,d) 2 (a) 2 (w) 3 Price 1 1 1 1 1 (b) 1 1 Pit 1 1 1 1 1 1 1 Searly 1 1 1 1 1 1 1 Tilly 1 1 1 1 1 1 1 Willow 1 1 1 1 (p) 1 (b) 1 1 Cockatoo 1 1 2 2 (t) 1 1 1 2 Zingari 1 1 1 1 1 1 1 1 Koolatah 2 1 1 3 (t) 2 (s,p) 1 2 (w) 3 Wrotham 2 1 1 3 (t) 2 (p) 1 2 (w,r) 3 UG 1 1 2 (g) 2 (d) 3 (c) 3 (r) 3 PG 1 1 2 (g) 2 (d) 2 (b) 2 (r) 2 AG 1 1 2 (t) 2 (d) 2 (a) 1 2 UM 1 1 2 (g) 1 3 (c) 3 (r) 3 PM 1 1 1 2 (d) 2 (b) 2 (r) 2 AM 1 1 2 (t) 2 (d) 2 (a) 1 2 UB 1 1 1 1 1 3 (r) 3 PB 1 1 1 1 1 2 (r) 2 AB 1 1 3 (t) 2 (s) 1 1 3 UT 1 1 1 1 1 2 (r) 2 PT 1 1 1 1 1 1 1 AT 1 1 1 1 1 1 1

Limitations and Suitability – SUGAR Degree of severity of limitation – 1 = nil or minor, 2 = moderate, 3 = high (severe) Suitability Class – 1 = suitable with nil to minor limitations, 2 = suitable with moderate limitations, 3 = unsuitable Soil / Soil Soil Drainage Plant Avail. Soil Physical Soil Chemical Soil Erosion Adverse Site SUITABILITY Landscape Water Condition Condition Hazard Factors CLASS (1-3) Blakens 3 (f,w) 1 2 (c,h,t) 3 (s,p,d) 2 (a) 3 (t) 3 Bierwirth 1 1 1 1 1 (b) 2 (t) 2 Mundy 1 1 1 1 1 1 1 Mills 2 (f) 1 1 1 1 2 (t) 2 Minty 3 (f,w) 1 2 (c,h,t) 3 (s,p,d) 2 (a) 2 (t) 3 Price 1 1 1 1 1 (b) 2 (t) 2 Pit 1 1 1 1 1 1 1 Searly 1 1 1 1 1 1 1 Tilly 1 1 1 1 1 1 1 Willow 1 1 1 1 (p) 2 (b) 1 1 Cockatoo 1 1 2 2 (t) 1 1 1 2 Zingari 1 1 1 1 1 1 1 1 Koolatah 2 3 (f,w) 1 2 (c,h,t) 2 (s,p) 1 3 (t) 3 Wrotham 2 2 (w) 1 2 (c,t) 2 (p) 2 (b) 2 (t,r) 2 UG 1 1 1 2 (d) 1 3 (r,t) 3 PG 1 1 1 2 (d) 1 2 (t) 2 AG 2 (f) 1 1 2 (d) 1 3 (t) 3 UM 1 1 1 1 1 2 (l) 2 PM 1 1 1 2 (d) 1 2 (t) 2 AM 2 (f) 1 1 2 (d) 1 2 (t) 2 UB 1 1 1 1 1 3 (r) 3 PB 1 1 1 1 1 3 (r) 3 AB 3 (f) 1 1 2 (s) 1 2 (t) 3 UT 1 1 1 1 1 2 (r,l) 2 PT 1 1 1 1 1 1 1 AT 2 (f) 1 1 1 1 2 (t) 2

Limitations and Suitability – RICE Degree of severity of limitation – 1 = nil or minor, 2 = moderate, 3 = high (severe) Suitability Class – 1 = suitable with nil to minor limitations, 2 = suitable with moderate limitations, 3 = unsuitable Soil / Soil Soil Drainage Plant Avail. Soil Physical Soil Chemical Soil Erosion Adverse Site SUITABILITY Landscape Water Condition Condition Hazard Factors CLASS (1-3) Blakens 1 1 1 2 (s,p,d) 1 2 (t) 2 Bierwirth 3 (d) 1 1 1 1 1 3 Mundy 3 (d) 1 1 1 1 1 3 Mills 3 (d) 1 1 1 1 1 3 Minty 1 1 1 2 (s,p,d) 1 2 (t) 2 Price 3 (d) 1 1 1 1 1 3 Pit 3 (d) 1 1 1 1 1 3 Searly 3 (d) 1 1 1 1 1 3 Tilly 3 (d) 1 1 1 1 1 3 Willow 3 (d) 1 1 1 1 1 3 Cockatoo 1 3 (d) 2 1 1 1 1 3 Zingari 1 3 (d) 1 1 1 1 1 3 Koolatah 2 1 1 1 2 (s,p) 1 2 (t) 2 Wrotham 2 1 1 1 2 (p) 1 2 (t,r) 2 UG 3 (d) 1 1 2 (d) 3 (c) 3 (r,l) 3 PG 3 (d) 1 1 2 (d) 3 (b) 2 (r) 3 AG 3 (d) 1 1 2 (d) 1 1 3 UM 3 (d) 1 1 1 1 3 (r,l) 3 PM 3 (d) 1 1 2 (d) 2 (b) 1 3 AM 3 (d) 1 1 2 (d) 1 1 3 UB 3 (d) 1 1 1 1 3 (r) 3 PB 3 (d) 1 1 1 1 2 (r) 3 AB 2 (d) 1 1 2 (s) 1 1 2 UT 3 (d) 1 1 1 1 1 3 PT 3 (d) 1 1 1 1 1 3 AT 3 (d) 1 1 1 1 1 3 Explanation of limitation codes used in Appendix 1

Drainage: (f) flooding, (w) waterlogging, (d) free draining Physical Condition: (c) cracking, (h) hard consistence, (s) surface condition, (p) pan, (g) gravel or segregations, (t) texture class Chemical Condition: (s) salinity risk, (p) adverse pH, (d) sodicity Erosion Risk: (a) long low slopes, (b) 2-5% slope, (c) 5-10% slope, (d) >10% slope Adverse Site Factors: (t) wet season access and traficability, (l) landscape complexity, (r) rock, (w) workability, (d) soil depth.

Footnotes:

1 Perry et al. (1970) 2 Galloway et al. (1964) APPENDIX 2 - Soil Type and Soil Landscape Descriptions

Soil Type Descriptions

Four soil descriptions have been adopted directly from land system reports (Perry et al. 1964 and Galloway et al. 1970). These are from areas where access proved difficult during fieldwork or where time did not permit thorough investigation. Their main characteristics, limitations and agricultural potential are outlined below.

Cockatoo (Perry et al. 1964) Characteristics: Coarse sandy profiles, either uniform or with slight increase in texture down the profile, colour variable from red to yellow and light grey, structure single grain or massive, consistence loose or soft, pH strongly acid to neutral. Associated with landscapes of low to moderate relief, surface runoff is low due to high infiltration, internal drainage is medium to rapid. Limitations: Low PAWC, low nutrient status Agricultural Potential: Moderate

Zingari (Perry et al. 1964) Characteristics: Reddish to brownish sandy clay loams to light clays grading to red sandy light to medium clay at 30cm. Sub soils have a very hard consistence and few yellowish mottles, pH medium acid to neutral. Associated with landscapes of low relief. Parent materials diverse being alluvial or colluvial material or derived from sedimentary, metamorphic or igneous rocks. Surface run-off and internal drainage are variable. Limitations: Low nutrient status, hardsetting surface particularly with cultivation. Agricultural Potential: Moderate to good.

Koolatah (Galloway et al.1970) Characteristics: Very deep dark grey to brown medium to heavy clays with strong alkaline mottled subsoil, commonly with a hardsetting silty clay overlay (15-20cm). Structure is medium to coarse angular blocky throughout or becoming massive at depth, consistence is firm to very hard. Reaction trend is moderately acid at the surface gradually becoming strongly alkaline at depth. Limitations: Imperfect to very poor drainage, annual flooding, possible salinity at depth. Agricultural Potential: Low

Wrotham (Galloway et al.1970) Characteristics: Very dark moderately deep to very deep cracking clays developed on Cretaceous shale material near Wrotham Park. The relief is very gently undulating to nearly level with slopes of 1-2%, occasionally up to about 4%. Linear gilgais occur in some areas. Prominent mottling occurs in the lower profile in some poorly drained situations and a self mulching surface layer develops in some well drained sites. The underlying soil has medium to very coarse blocky structure and firm to very hard consistence. Soil reaction is slightly acid to neutral at the surface and grades to strongly alkaline at depth (over 1 metre). Some areas are gravelly, where residuals of deeply weathered Tertiary sandstone occur upslope of these soils. Limitations: poor to moderate drainage, limited workable moisture range, some areas of moderate slope, minor residual stone and gravel. Agricultural Potential: Moderate

The following ten soil descriptions are based on site data and other information collected during fieldwork conducted for the purpose of this survey. Soils outside key areas or those considered of little importance to agricultural development are not discussed. Areas of rocky, shallow soils on hilly and rolling country are mapped as H (hilly) and R (rolling) with a second letter denoting the dominant geology of parent material G (granitic), B (basalt), M (metamorphic), S (sandstone) or T (Tertiary deposits).

Soil Landscape Descriptions

The following soil landscapes have been used to assess potential agricultural suitability for the Lynd River, Einasleigh/Copperfield Rivers, McBride Plateau and Bundock/McKinnons Creeks key areas. They are based on a landscape and parent material breakdown with additional information from existing reports covering the area (Perry et al. 1964 and Grundy and Bryde 1989). Parent materials have been determined from existing geological mapping and an interpretation of airborne gamma spectrometry data. Very little fieldwork was conducted in the area during this survey.

Map Landform Geology Soils Limitations Agricultural Code Suitability UG Undulating plains to A range of igneous Podzolics, shallow yellow Moderate to steep slopes, LOW undulating low hills. Gently and volcanic rocks of earths and sodic duplex soils susceptible to erosion, hardsetting inclined slopes 3-10%. various ages including surface, low to moderate PAWC PG Gently undulating to granites, rhyolites, Sodic duplex soils and Susceptible to erosion, poor LOW-MOD undulating plains and rises. granodiorites, diorites yellow earths drainage, light surface textures, Very gently inclined slopes etc. Fine grained, silty low PAWC 1-3%. to sandy alluvium. AG Level to gently undulating Sodic soils, yellow earths, Poor drainage, poor wet season MOD plains. Level to very gently cracking clays, grey clays trafficability, low to moderate inclined slopes <1-2% and solodic soils PAWC, silty hardsetting surface UM Undulating plains to A range of Stony red and yellow earths, Rocky, gravelly, moderate to steep LOW undulating low hills. Gently metamorphic rocks red podzolic and non-sodic slopes, susceptible to erosion, inclined slopes 3-10%. including gneiss, duplex soils dissected landscape, low to schist, greywacke etc. moderate PAWC PM Gently undulating to Medium grained Podzolics and red and yellow Susceptible to erosion, hardsetting MOD undulating plains and rises. alluvium. earths surface, hard to very hard subsoils, Very gently inclined slopes low to moderate PAWC 1-3%. AM Level to gently undulating Podzolics and red and yellow Hardsetting surface, hard to very MOD-GOOD plains. Level to very gently earths hard subsoils, low to moderate inclined slopes <1-2% PAWC Map Landform Geology Soils Limitations Agricultural Code Suitability UB Undulating plains to Olivine basalts. Fine Stony kraznozems and Rocky, moderate to steep slopes, LOW undulating low hills. Gently to medium grained euchrozems susceptible to erosion inclined slopes 3-10%. alluvium. PB Gently undulating to Stony kraznozems, Rocky, hardsetting surface, LOW-MOD undulating plains and rises. euchrozems and red earths subject to structural decline with Very gently inclined slopes continued cultivation. Some areas 1-3%. of low rockiness (difficult to map) AB Level to gently undulating Black earths and cracking Poor wet season trafficability, MOD plains. Level to very gently clay soils some areas of gilgai, high subsoil inclined slopes <1-2% pH, sodicity may reduce PAWC, potential salinity risk at depth (50- 80cm) UT Undulating plains to Tertiary lateritic Shallow red and yellow Moderate to steep slopes, LOW undulating low hills. Gently deposits, sandstones, earths, light textured brown susceptible to erosion, landscape inclined slopes 3-10%. conglomerate and soils, lithosols complexity PT Gently undulating to shales. Medium to Red and yellow earths, Low to moderate PAWC, low MOD-GOOD undulating plains and rises. coarse grained sandy duplex soils and light nutrient status soils, light textures, Very gently inclined slopes alluvium textured brown soils hard setting particularly under 1-3%. cultivation AT Level to gently undulating Red and yellow earths, Low to moderate PAWC, low MOD-GOOD plains. Level to very gently duplex soils and light nutrient status soils, light textures, inclined slopes <1-2% textured brown soils hard setting particularly under cultivation

APPENDIX 3 –

Soil Sample Chemical Analysis Results

Soil Site Depth pH EC Cl Na Mg Ca CEC N Bicarb P K Organic C 15 bar Type No. cm 1:5 water dS/m mg/kg meq/100g meq/100g meq/100g meq/100g % mg/kg meq/100g % % Blakens 14 80 8.7 0.96 1333 7.4 7.1 18.0 36 .01 0.60 18 Blakens 15 40 9.0 0.09 34 3.8 7.1 29.0 52 10 1.60 0.26 26 Blakens 15 90 9.0 0.41 625 8.1 6.5 27.0 53 .02 13 1060 0.26 28 Blakens 26 30 8.7 0.07 56 0.4 11.0 29.0 48 12 0.64 0.50 18 Blakens 26 90 9.3 0.13 20 4.6 12.0 25.0 49 .02 4 0.36 0.30 21 Blakens 28 80 9.1 0.40 645 5.6 12.0 16.0 39 .02 0.69 20 Blakens 32 40 9.1 0.16 84 3.8 11.0 19.0 40 3 0.40 0.23 18 Blakens 32 90 8.0 1.58 1025 6.6 12.0 19.0 39 .01 0.44 19 Minty 9 40 9.0 0.14 64 1.9 4.8 20.0 29 15 0.82 0.41 16 Minty 9 75 8.9 0.56 877 4.2 5.1 15.0 27 .03 0.77 16 Minty 36 40 9.3 0.22 200 3.7 6.6 16.0 29 3 0.27 0.20 14 Minty 36 90 8.9 0.85 1165 8.0 8.0 12.0 31 .01 0.36 17 Minty 37 5 6.0 0.31 302 1.1 8.0 3.2 22 1.50 20

Soil Sample Emerson Disperion Test (Emerson 1967, 1991) Results

Soil Type Site No. Depth cm Slaking Dispersion (1st test) Dispersion Class Time (sec) % 2 hrs 4 hrs Blakens 14 80 120 50 1 1 1 severe Blakens 15 90 120 90 1 1 1 severe Blakens 26 90 120 5 3a-6 3a-6 1 severe Blakens 28 80 120 85 1 1 1-2 severe to mod- slight Blakens 32 90 120 80 3a-6 1-2 1 severe Minty 9 75 60 100 3a (sl) 1 1 severe Minty 36 90 120 80 1-2 1 1 severe

Soil Types of the Gulf Region

Bierwirth (Bw)

Runoff: Low, due to high infiltration rate.

Permeability: Moderately to highly permeable. Inundation: Nil.

Microrelief: Minor presence of termite mounds.

Plant Available Water Holding Capacity: Moderate available moisture range.

Soil Surface Condition: Soft.

Chemical Data:

Soil samples for chemical analysis where not taken however there is an indication the soil may be slightly sodic at depth.

Management Considerations:

These soils are of reasonable agricultural potential with low salts and generally low slopes. There is a potential for waterlogging problems due to poor drainage in the clays at depth. There is also a possibility of sodicity in the clays at depth, which may reduce PAWC.

Soil: Bierwirth (Bw)

Concept: Moderately deep, duplex to gradational, yellow loamy sands over massive light clays, with slight mottling and many ferromanganiferous nodules at depth. Slightly acid reaction trend.

Classification: Aust. Soil Yellow Chromosol Great Soil Group: Yellow Podzolic Principle Profile Form: Dy2.32

Geology: Parent material diverse (Metamorphics). Landform: Level to very gently undulating plains. Vegetation: Mid-high open woodland with sparse shrubs. Profile Morphology:

Horizon Lower Depth Description A1 .05 to .08m Very dark grey (10YR 31); loamy sand; massive; moist, soft; field pH 7.0; gradual change to- A2 .15 to .18m Greyish brown (10YR 52); loamy sand; massive; dry, soft; field pH 6.5; clear change to- B1 .35 to .40m Light olive brown (2.5Y 54); clay loam sandy; massive; dry, firm; 5% orange mottles; field pH 6.0; gradual change to- B2 .60 to .68m Olive yellow (2.5Y 66); light clay sandy; massive; dry, firm; 10% orange mottles; 5% ferromanganiferous nodules; field pH 5.5; gradual change to- B3 .80 to 1.00m Light olive brown (2.5Y 54); light clay; massive; dry, firm; 40% red mottles; 2% 10mm quartz; 40% 10mm ferromanganiferous nodules; may be sodic; field pH 6.0

Location: Small areas associated with the Gilbert and Einasleigh river systems.

Soil Types of the Gulf Region

Blakens (Bk)

Runoff: Slow except areas of slight slope. Free water can remain on the surface. Permeability: Slow to moderately permeable. Inundation: Some areas annually for up to 1 month, variable.

Microrelief: Large areas of no microrelief, variable degrees of gilgai in others.

Plant Available Water Holding Capacity: Good available moisture range.

Soil Surface Condition: Self mulching and cracking.

Chemical Data: Limited chemical data is available for these soils however results indicate soils are strongly alkaline and sodic with high salt loads. Chemical data is shown in Appendix 3.

Management Considerations: Soils have a narrow moisture range for working, with potential soil compaction and shearing problems. Cracking depth varies (due to the swelling properties of the clays) and may pose problems for germination and crop establishment, however maintaining soil moisture will prevent excessive cracking. Salt contents are high thus irrigation water needs to be applied in large amounts to maintain downward leaching to move salts to lower depths, drainage may be a problem. There is a need to consider potential for groundwater recharge and saline discharge downslope. The hard consistence of the clays may pose a problem to root penetration. Also alkaline pH in the subsoil could inhibit root growth and sodicity may reduce PAWC. In areas of slight slope the dispersive nature of the subsoil is conducive to gully erosion. Soil: Blakens (Bk)

Concept: Very deep, uniform, cracking, self mulching grey and occasionally brown, dominantly massive clays with alkaline reaction trend formed in situ or on colluvial and alluvial plains. Occasional areas of minor gilgai. Subsoils are sodic and dispersive, with varying amounts of carboniferous nodules.

Classification: Aust. Soil Grey or Brown Vertosols Great Soil Group: Grey Clay, Brown Clay Principle Profile Form: Uf6.5, Ug6.2

Geology: Rolling Downs fine grained marine sediments. Landform: Level to very gently undulating plains. Vegetation: Mid-high to tall, mid-dense tussock grassland, mostly treeless. Profile Morphology: Horizon Lower Depth Description A1 .08 to .20m Very dark greyish brown to olive brown (10YR 32 to 2.5Y 54); light to light medium clay; strongly self mulching; dry, very hard occasionally sodic; field pH 7.0-8.5; gradual change to- B1 .40 to .90m Very dark greyish brown to light olive brown (10YR 32 to 2.5Y 56); light medium to medium heavy clay; massive, some slickensides; dry, hard; occasional 2-5% 2-4mm subangular quartz; occasional 2% 3mm soft manganiferous or carbonate nodules; sodic; field pH 8.0-9.0; diffuse change to-

B2 .90 to 1.10m+ Dark greyish brown to light olive brown (10YR 42 to 2.5Y 54) light medium to medium clay; massive with weak lenticular peds, some slickensides; dry, very hard; occasional 2-5% 3mm carbonate nodules; sodic; field pH 8.0-9.0.

Location: Extensive areas on the inland and lowland plains of the gulf region.

Soil Types of the Gulf Region

Mills (Ms)

Runoff: Low, due to high infiltration rate.

Permeability: Moderately to highly permeable. Inundation: Some areas annually, other areas frequently.

Microrelief: Nil.

Plant Available Water Holding Capacity: Moderate available moisture range.

Soil Surface Condition: Firm.

Chemical Data: Soil samples for chemical analysis where not taken as this soil is regarded as a nil to minor chemical condition limitation soil.

Management Considerations: These soils are suitable for agriculture however, there is a potential for the surface to be hard setting when cultivated. In some areas there may be some landscape complexity with the presence of small depressions. There may be some management implications relating to soil moisture levels as these soils are well drained. Soil: Mills (Ms)

Concept: Very deep, uniform, brown alluvial fine sandy loams, with a neutral reaction trend.

Classification: Aust. Soil Brown Tenosol Great Soil Group: Alluvial Soil Principle Profile Form: Um1.92

Geology: Alluvium, from granitic and rhyolitic parent materials.

Landform: Level to very gently undulating levees, terraces, alluvial plains and back plains.

Vegetation: Tall open woodlands. Profile Morphology:

Horizon Lower Depth Description A1 .20 to .25m Dark greyish brown (10YR 42); silty loam; massive; moist, soft; field pH 7.0; diffuse change to- A2 .48 to .55m Dark brown (7.5YR 43); fine sandy loam; dry, soft; field pH 7.0; diffuse change to- B1 .75 to .82m Dark brown (10YR 43); fine sandy loam; dry, soft; field pH 7.0; diffuse change to- B2 1.20m+ Dark brown (7.5YR 44); fine sandy loam; dry, weak; field pH 7.0

Location: Small areas associated with the Gilbert and Einasleigh River systems.

Soil Types of the Gulf Region

Minty (My)

Runoff: Slow.

Permeability: Slow to moderately permeable. Inundation: Some areas annually.

Microrelief: Small areas of slight gilgai.

Plant Available Water Holding Capacity: Good available moisture range.

Soil Surface Condition: Firm surface, some areas slightly self mulching and cracking.

Chemical Data: Limited chemical data is available for these soils however results indicate soils are strongly alkaline and sodic with high salt loads. Chemical data is shown in Appendix 3.

Management Considerations: Soils have a narrow moisture range for working, with a potential problem of shearing and compaction (due to the swelling properties of the clays). Salt contents are high thus irrigation water needs to be applied in large amounts to maintain downward leaching to move salts to lower depths. There is a need to consider potential for groundwater recharge and saline discharge downslope. The hard consistence of the clays may pose a problem to root penetration. Also alkaline pH in the subsoil could inhibit root growth and sodicity may reduce PAWC.

Soil: Minty (My)

Concept: Very deep, uniform to occasionally gradational, brown massive slightly self mulching clays, with alkaline reaction trend. Some slight gilgai and sodic at depth.

Classification: Aust. Soil Brown Kandosol, Brown Vertosol Great Soil Group: Brown Clay Principle Profile Form: Uf6.3, Gn2.43

Geology: Rolling Downs Group. Landform: Level to gently undulating plains. Vegetation: Mid-high, mid-dense to sparse tussock grassland. Profile Morphology:

Horizon Lower Depth Description A1 .05 to .10m Dark yellowish brown to olive brown (2.5Y43 to 10YR 44); heavy clay loam to light medium clay; slightly self mulching; massive; moist, firm; occasional 2-5% 2-10mm subangular quartz; field pH 6.5-7.0; gradual change to-

A3 .15 to .20m Dark greyish brown to dark yellowish brown (10YR 42 to 10YR 34); light to medium clay; massive; dry, hard; occasional 2% 2mm angular quartz; field pH 7.0-8.0; gradual change to- B1 .40 to .70m Dark yellowish brown to olive brown (2.5Y 44 to 10YR 36); medium to heavy clay; massive; some slickensides; dry, hard; occasional 2-5% 20mm subangular quartz; field pH 8.0-9.0; diffuse change to-

B2 .90 to 1.10m+ Dark yellowish brown to dark olive brown (10YR 36 to 2.5Y 33); medium to heavy clay, massive to weak; moist, hard; 2% 5-8mm subangular quartz; 2% 2mm manganiferous nodules; 2% 3mm calcium carbonate nodules; sodic; field pH 7.5-8.5

Location: Extensive areas north and east of Cloncurry and areas along the Leichhardt River.

Soil Types of the Gulf Region

Mundy (Md)

Runoff: Low, due to high infiltration rate.

Permeability: Highly permeable. Inundation: Nil.

Microrelief: Minor presence of termite mounds.

Plant Available Water Holding Capacity: Surface poor with moderate below 35cm.

Soil Surface Condition: Soft.

Chemical Data: Soil samples for chemical analysis where not taken as this soil is regarded as a nil to minor chemical condition limitation soil.

Management Considerations: These soils are potentially good agricultural soils. Surface textures are sandy so moisture regimes need to be monitored closely. There is a possibility of minor gully erosion.

Soil: Mundy (Md)

Concept: Very deep, gradational yellow earths, with neutral reaction trend.

Classification: Aust. Soil Yellow Kandosol Great Soil Group: Yellow Earth Principle Profile Form: Gn2.22

Geology: Tertiary sandstone. Landform: Level to very gently undulating plains. Vegetation: Mid-high woodlands. Profile Morphology:

Horizon Lower Depth Description A1 .12 to .18m Dark brown (7.5YR 32); loamy sand; massive; dry, weak; field pH 6.0; gradual change to- B1 .30 to .35m Brownish yellow (10YR 66); loamy sand; massive; dry, weak; field pH 6.0; gradual change to- B2 1.20m+ Reddish yellow (7.5YR 76); clay loam sandy; massive; dry, weak; field pH 7.0

Location: Small areas mainly along the Gilbert River but also in other areas of sandstone parent materials.

Soil Types of the Gulf Region

Pit (Pt)

Runoff: Generally low due to high infiltration.

Permeability: Highly permeable. Inundation: Nil.

Microrelief: Nil.

Plant Available Water Holding Capacity: Low to moderate.

Soil Surface Condition: Firm.

Chemical Data: Soil samples for chemical analysis where not taken as this soil is regarded as a nil to minor chemical condition limitation soil.

Management Considerations: These soils are of reasonable agricultural potential. There is presence of minor sheet erosion in some areas that indicates some erosion potential which may impact on management practices.

Soil: Pit (Pt)

Concept: Deep, uniform to occasionally gradational, red earthy sands, clayey at depth,with a neutral reaction trend.

Classification: Aust. Soil Red Tenosol Great Soil Group: Red Earthy Sand Principle Profile Form: Uc5

Geology: Tertiary deposits, mainly sandstone. Landform: Level to very gently undulating outwash plains. Vegetation: Tall open woodlands. Profile Morphology:

Horizon Lower Depth Description A1 .06 to .09m Dark reddish brown (2.5YR 34); loamy sand; massive; dry, soft; field pH 6.5; gradual change to- A3 .32 to .40m Reddish brown (2.5YR 44); loamy sand; massive; dry, soft; field pH 7.0; diffuse change to- B2 .70 to .75m Reddish brown (2.5YR 44); sandy loam; massive; dry, firm; field pH 7.0; clear change to- D1 1.20m+ Red (10R 46); light clay; massive; dry, firm; field pH 7.0.

Location: Small areas in the Gilbert and Mitchell River catchments.

Soil Types of the Gulf Region

Price (Pi)

Runoff: Low, due to high infiltration rate.

Permeability: Medium to rapid permeability. Inundation: Annual and with a duration of days.

Microrelief: Nil.

Plant Available Water Holding Capacity: Moderate with good below 20cm.

Soil Surface Condition: Soft to firm.

Chemical Data: Soil samples for chemical analysis where not taken as this soil is regarded as a nil to minor chemical condition limitation soil.

Management Considerations: Soils have a high infiltration rate and are well drained so moisture ranges in the soil need monitoring. Slightly alkaline pH at depth may have some specific crop management implications. These soils have a low salt content.

Soil: Price (Pi)

Concept: Deep, uniform to occasionally gradational, brown massive clay loams, with slight alkaline reaction trend.

Classification: Aust. Soil Brown Kandosol Great Soil Group: Alluvial Brown Earth Principle Profile Form: Um5.22

Geology: Alluvium. Landform: Level to gently undulating alluvial terraces and levees. Vegetation: Mid-high to tall open woodland. Profile Morphology:

Horizon Lower Depth Description A1 .17 to .25m Strong brown (7.5YR 46), fine sandy clay loam; massive; dry, firm; field pH 6.0; gradual change to- B1 .55 to .70m Dark brown (7.5YR 34); clay loam to light clay; massive; dry, firm; 1% 2mm manganiferous nodules; field pH 6.5; diffuse change to- B2 .90m+ Dark brown (7.5YR 34); heavy clay loam; massive; dry, firm; field pH 8.5

Location: Medium areas along the Leichhardt and Flinders River systems. Soil Types of the Gulf Region

Searly (Sa)

Runoff: Slow in vegetated areas with rapid runoff on scalded areas.

Permeability: Moderately to highly permeable. Inundation: Nil.

Microrelief: Minor presence of termite mounds.

Plant Available Water Holding Capacity: Moderate available moisture range.

Soil Surface Condition: Areas of hard setting or scalded surface.

Chemical Data: Soil samples for chemical analysis where not taken as this soil is regarded as a nil to minor chemical condition limitation soil.

Management Considerations: Generally these soils are reasonable agricultural soils. In some areas mottling indicates there may be a drainage limitation, also the presence of a nodular layer at depth may have some management implications. There are some management requirements for establishment of crops or pasture in the scalded areas.

Soil: Searly (Sa)

Concept: Deep, gradational, mottled yellow earths, nodular at depth with neutral reaction trend.

Classification: Aust. Soil Yellow Kandosol Great Soil Group: Yellow Earth Principle Profile Form: Gn2.22, Gn2.65

Geology: Argillaceous sediments. Landform: Level to very gently undulating plains. Vegetation: Medium high open woodlands with some bare scalded areas. Profile Morphology:

Horizon Lower Depth Description A1 .08 to .12m Dark brown (7.5YR 32); sandy loam; massive; dry, firm; field pH 6.5; gradual change to- A2/A3 .20 to .25m Dark brown to yellowish brown (7.5YR 43 to 10YR 56); sandy clay loam to clay loam; massive; dry, firm; field pH 6.0-6.5; gradual change to- B1/B21 .40 to .45m Brown to brownish yellow (7.5YR 54 to 10YR 66); light clay; massive; dry, firm; 3% 10mm ferromanganiferous nodules; field pH 6.0-6.5; gradual change to- B2/B22 .55 to .60m Strong brown to pale brown (7.5YR 56 to 10YR 74); light clay; massive; dry, firm; 5-10% 10mm ferromanganiferous nodules; 30-40% distinct red or orange mottles; field pH 6.0-7.0; gradual change to-

B23 .80m+ Pale brown (10YR 73); light clay; massive; dry, firm; 40% 25mm ferromanganiferous nodules; 45% distinct red mottles; field pH 7.0.

Location: Small areas associated with the Gilbert and Einasleigh River systems.

Soil Types of the Gulf Region

Tilly (Ti)

Runoff: Low, due to high infiltration rate.

Permeability: Medium to rapid permeability. Inundation: Nil.

Microrelief: Nil.

Plant Available Water Holding Capacity: Moderate with good below 20cm.

Soil Surface Condition: Firm, but can be powdery when dry.

Chemical Data: Soil samples for chemical analysis where not taken as this soil is regarded as a nil to minor chemical condition limitation soil.

Management Considerations: The soil surface has a potential to be powdery when dry. This combined with high infiltration and good permeability in the soil surface, make for a need to monitor soil moisture ranges. The subsoil could become slightly adhesive with increased moisture. These soils have a low salt content.

Soil: Tilly (Ti)

Concept: Deep, uniform to gradational, red massive sandy clay loams, with a neutral reaction trend.

Classification: Aust. Soil Red Kandosol Great Soil Group: Red Earth Principle Profile Form: Gn2.15

Geology: Alluvium and colluvium from sandstone and metamorphics.

Landform: Level to gently undulating plains, also found in small areas on the undulating footslopes.

Vegetation: Mid-high open woodland. Profile Morphology:

Horizon Lower Depth Description A1 .08 to .12m Reddish brown (5YR 44), light fine sandy clay loam; massive; dry, soft/firm; field pH 5.8-6.5; gradual change to- A2 .18 to .22m Yellowish red (5YR 46), fine sandy clay loam; massive; dry, soft; field pH 6.5; gradual change to- B1 .28 to .30m Dark reddish brown (2.5YR 34); fine sandy clay loam; massive; moist, soft; field pH 7.0; gradual change to- B2 1.00m+ Red (2.5YR 48); light clay; massive; moist, soft; field pH 7.0

Location: Lowland and alluvial plains near Gregory Downs.

Soil Types of the Gulf Region

Willow (Ww)

Runoff: Generally low due to high infiltration.

Permeability: Moderately to highly permeable. Inundation: Some areas annually.

Microrelief: Nil.

Plant Available Water Holding Capacity: Moderate to good in the clayey subsoils.

Soil Surface Condition: Firm.

Chemical Data: Soil samples for chemical analysis where not taken as this soil is regarded as a nil to minor chemical condition limitation soil.

Management Considerations: Generally these soils are reasonable agricultural soils. Some low slope areas may require soil conservation measures. High pH in subsoils could affect crop performance.

Soil: Willow (Ww)

Concept: A group of deep, gradational to occasionally duplex, yellow to brown earths, clayey at depth with a neutral reaction trend; over buried soils with alkaline reaction trend; carbonate nodules at depth in places.

Classification: Aust. Soil Yellow or Brown Kandosols Great Soil Group: Yellow Earth Principle Profile Form: Gn2 dominantly

Geology: Tertiary deposits, mainly deeply weathered sandstones. Landform: Level to gently undulating infill or outwash plains. Vegetation: Low to mid-high open woodlands.

Profile Morphology:

Horizon Lower Depth Description A1 .05 to .08m Dark brown to light yellowish brown (10YR33 to 2.5Y 63/64); sand to sandy loam; massive; dry, soft; field pH 5.5-6.5; clear change to- A2 .12 to .25m Dark brown to light yellowish olive brown (10YR 33 to 2.5Y 63/56); loamy sands; massive; dry, soft; occasional 2% 3mm subangular quartz; field pH 5.8-6.5; clear change to- B1 .35 to .70m Dark brown to olive yellow (10YR33 to 2.5Y 6/6); fine sandy clay loam to light clay; massive; soft to firm; 5% 4mm distinct orange and yellow mottles; field pH 5.8-7.0; clear change to- 2A1 .35 to .80m Dark greyish brown to light yellowish grey brown (10YR42 to 2.5Y 64/2); occasional 2-5% 2-5mm yellow or grey mottles; clayey sands to sandy clay loams, massive; firm; 2% 3mm subangular quartz; field pH 5.8-7.5; clear change to-

3A1 .75 to 1.10m+ Light olive brown to light yellowish brown (2.5Y 56/63); sandy light to sandy light-medium clay; dry, firm to hard; field pH 9.0. 3B2 .95 to 1.30m Light yellowish brown (2.5Y 63/64); light clay to light medium clay; 10% 3mm calcium concretions; 2% 3mm soft manganiferous concretions; field pH 9.0

Location: In association with the Flinders and Leichhardt catchments.

REFERENCES

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Biggs A.J.W. and Philip S.R. (1995). Soil Survey and Agricultural Suitability Assessment of Cape York Peninsula. CYPLUS NRO2 - Land Resource Assessment. Queensland Department of Primary Industries. QV95001.

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Emerson, W.W. (1991). Structural Decline of Soils, Assessment and Prevention. Australian Journal of Soil Research 29: 905-21.

Enderlin, N. (in prep.) Preliminary Agricultural Suitability Assessment of the Einasleigh Town Common Area. Department of Natural Resources.

Forster, B.A, Gilbert, E.J. and Passmore, J.G.I. (1988). Preliminary Irrigation Investigation Proposed Cave Hill Dam, Cloncurry. Queensland Department of Primary Industries. Project Report, QO88014.

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