Publication Date

11-2018

Series Number

411

Abstract

This report describes the soil and land resources of the Shay Gap study area (SA), which is south of Wallal Downs Station, in unallocated Crown land in the Shire of East Pilbara. It assesses the study area’s capability for three types of irrigated agriculture and examines land resources to ensure any future irrigation developments are sustainable and do not degrade the environment.

The Shay Gap SA lies within the West Canning Basin, an area of about 3500 square kilometres at the western margin of the onshore Canning Basin. The West Canning Basin has a substantial groundwater resource that provides fresh and fit-for-purpose water for a variety of uses.

Land use is intensifying nearby, via irrigation of soils and landforms similar to the Shay Gap SA. Small- to medium-scale horticulture enterprises have been developed over the past 30 years in the La Grange area.

The soils of surrounding areas that are currently used for irrigation are deep red sands and red sandy earths. They are well drained to rapidly drained and have no perched watertable, potentially enabling year-round production. Analyses from established horticultural properties indicate soils do not show any chemical or major physical limitations that would prevent their use for irrigated agriculture, provided that production systems maintain a balanced water and nutrient regime for optimal crop growth.

The main degradation hazard limiting the agricultural capability of soil and landscapes in the Shay Gap SA is erosion by wind and water. Other hazards — subsoil acidification and compaction — will require ongoing monitoring and management intervention. The ionic constituents of irrigation water will require monitoring and may influence management practices because of the low pH and phosphorus buffering capacity of the soil.

This land assessment identified 1430 hectares (ha) of land with fair capability for irrigated agriculture of high productive capacity, and another 11 000ha with fair capability for irrigated agriculture of moderate productive capacity, should sufficient water reserves be identified.

Number of Pages

117

Keywords

Shay Gap, West Canning Basin, soil suitability, land suitability, irrigated agriculture, Pilbara

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