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Department of Agriculture and Food, Western Australia






Wheat is grown on about 18 million hectares in the South-West Agricultural Region of Western Australia from north and east of Geraldton to Esperance in the south-east. Yields are frequently constrained by a range of soil factors.

This report uses existing conventional soil-landscape mapping to analyse the effects of 17 known soil constraints that limit crop production and roughly prioritises the areas where they occur.

Traditional land capability maps are prepared using a most-limiting factor approach, which assumes that ameliorating the most limiting constraint will result in a yield increase until the next most-limiting constraint is reached. Where there are few (1–3) overlapping soil constraints, regional-scale mapping — as used for this report — identifies land where spending time and money to ameliorate these constraints may be cost-effective in increasing economic returns because there is some yield benefit before the next constraint is reached. When many (>3) overlapping constraints occur, the returns from fixing one constraint may not be economic, due to the yield-limiting effects of the other constraints.

Information provided in this report is suitable for regional-, local- and catchment-scale planning. It uses unmapped proportionally allocated land units within map units. Where a land manager can identify these unmapped land units, it should be a reasonable starting point for farm-scale planning. At the very least, it prioritises likely constraints to be explored.

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soil constraints, soil-landscape mapping, map units, crop production, south-west of Western Australia


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