Investigations of the potential for irrigated agriculture on the Bonaparte Plains: land capability assessment report

This report describes 55 000 hectares of predominantly red sands and sandy loams — locally referred to as Cockatoo Sands — on the Bonaparte Plains about 70 kilometres north of the Ord River Irrigation Area, Kununurra. It builds on soil surveys conducted in 2009 and 2015, which identified significant areas of red soils in the Kununurra area that could be suitable for agriculture. The Cockatoo Sands generally have loamy, sand topsoils that grade to sandy loam with depth. The soil profiles are very deep, well drained to rapidly drained, and highly permeable. These soil characteristics support a large range of annual and perennial crops over the wet and dry seasons. The areas identified for agricultural development are predominantly Cockatoo Sand, loamy phase, and deep red earths that are classified as Haplic Mesotrophic Red Kandosols. Soil profiles typically have loamy, sand topsoils that grade to clayey sand and sandy loam within a metre. In general, the landscape is almost level, with most slopes less than 2%. Sandstone and limestone hills border the south and west of the study area, respectively. The land slopes to the north and east where ephemeral drainage lines and fringing freshwater springs meet coastal mudflats. Soil analysis indicates that Cockatoo Sands are strongly weathered with the clay fraction dominated by kaolin and quartz with minor haematite and goethite. The soil reaction trend is neutral, with topsoil pH in the range of 5.5 to 6.5 and subsoil pH in the range of 6.5 to 7.0. The upper 30–60cm of the soil profile has loamy sand to clayey sand soil textures that have a very low soil buffering capacity. This, combined with their low nutrient-retention ability, means that these soils will require careful management if they are used for irrigated agriculture. Under irrigated agriculture, soil acidity may increase over time, depending on the pH of the irrigation water and fertiliser management. The underlying sandy loam subsoils are compact, with soil bulk density in the range of 1.7 to 1.8 megagrams per cubic metre. To address this, deep-ripping prior to seeding is recommended for deep-rooted annual and perennial crops. Water erosion is a major risk because the region has a monsoonal climate. Under intense rainfall, sheet and rill erosion is likely to develop, particularly on long slopes of greater than 1% gradient. Therefore, development of the land requires consideration of the length of crop rows and slope. Slopes greater than 3% are considered not sustainable for annual cropping, while 5% slope is the upper limit for perennial crops where cultivation is infrequent and a protective groundcover can be maintained. This investigation identified 34 947ha of Cockatoo Sands (normal phase and loamy phase) with a moderate to high capability for irrigated agriculture. The potential for irrigated agriculture on the Bonaparte Plains depends on the development of suitable water supplies for irrigation

Soil assessment of the west Gingin area

Soils of approximately 80,000 hectares in the West Gingin area, 100 km north of Perth, were surveyed from 1987 to 1989. The area lies on the Swan Coastal Plain within the Gingin Shire. The soils were mapped by the free survey method at a scale of 1:50,000. Thirty-five major soil associations and complexes were identified. These soils have been formed from various parent materials in a a range of depositional environments. Siliceous sand and sodic soils formed in alluvial-lacustrine sediments predominate. The main soils were sampled for chemical and physical analysis and their morphological, chemical and physical properties are discussed in relation to land use. Results indicate that 30% of the unalienated lands have a high to moderate capability for general irrigated horticulture. The major soils involved are the weakly leached siliceous sands represented by Karakatta, Spearwood, Cowalla and Battordal Soil Series

The soils of South Carrabin Research Station -Light Land annex

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Identification and classification of “new” semi-arid soils from the Pilbara WA with potential additions to the Australian Soil Classification

As part of the Department of Primary Industries and Regional Development’s (DPIRD) Transforming Agriculture in the Pilbara (TAP) project, a land assessment of the region was conducted to identify areas with potential for irrigated agriculture. The morphology of the dominant soils is described together with their chemical and physical properties

Pindan soils in the La Grange area, West Kimberley: land capability assessment for irrigated agriculture, 2nd edition

This report identifies areas of Pindan country along the Great Northern Highway, south of Broome from Roebuck to Mandora, which have high potential for irrigated agriculture. The area contains significant reserves of potable groundwater defined by the La Grange groundwater allocation area, which is based on the surficial Broome Sandstone aquifer. Over the past 30 years, several small- to medium-scale irrigation developments have been successfully established in the region. The water opportunities project aims to identify and quantify the land and water resources of the region to ensure any future expansion of irrigated agriculture is sustainable and will not have a detrimental impact on other land uses, environmentally sensitive areas, such as groundwater-dependent ecosystems, or areas of traditional cultural heritage. Pindan soils that are currently used for irrigated agriculture are predominantly deep, red, sandy earths. These soils are well drained to rapidly drained and do not develop a persistent perched watertable during the wet season. These soil characteristics potentially allow for year-round access and cropping. This land assessment identified over 50 000 hectares of Pindan soils that have a high to fair capability for irrigated agriculture where potable groundwater is within 20 metres. Groundwater is the main limiting resource and if allocated for irrigated agriculture, it should be used sustainably. Its usage should be restricted to land having a high capability for the proposed land use. The second edition of this report contains corrections in the soil chemical analysis tables (Appendix B), a revision of the Pindan soils classification to the Australian Soil Classification subgroup level, and corrections in the soil site classification table (Appendix C)

Soil assessment of the Weaber Plain (Goomig) farmlands

In 2008, the Ord Irrigation Expansion Project was approved by the Western Australian Government to develop irrigated agriculture on the Weaber Plain (Goomig) As part of the environmental planning and approvals process, the WA Government was required to prepare a groundwater management plan and a hydrodynamic plan. As a result, the Department of Agriculture and Food, Western Australia (DAFWA) was requested to lead an investigative program to support a second phase of modelling. The project was divided into five components: two addressing deficiencies related to groundwater, two relating to soils and subsoils, and one addressing surface and groundwater quality aspects. This report summarises the two soil assessment components of the project

Cockatoo Sands in the Victoria Highway and Carlton Hill areas, East Kimberley: land capability assessment for developing irrigated agriculture

This report identifies areas of Cockatoo Sands adjacent to the Ord River Irrigation Area (ORIA), Kununurra, with high potential for developing irrigated agriculture. It builds on a reconnaissance soil survey conducted in 2009 which identified significant areas of sandy and loamy soils in the Kununurra area that could be suitable for agriculture