Why model wheat yield potential?
The modelling in the attached report — Wheat yield potential and land management constraints in the south-west of Western Australia — indicates where improved management of soil constraints could improve wheat yields. The modelling results could be used in regional economic development strategies and provide some guidance for farm level economics.
Findings of the assessment
- 3.2 million hectares (18%) of the land modelled was near yield potential
- 9.5 million hectares (53%) of land could gain a wheat yield increase from treating soil constraints
- 4.3 million hectares (24%) has multiple (4 or more) constraints, which makes treatment difficult
- about 1.5 million hectares (8%) of low productivity land, such as areas of rock outcrop and salt scalds, would remain unproductive.
Important constraints and recent updates
We used our soil-landscape mapping data for this assessment, and ranked wheat productivity for the mapped areas based on the most limiting factor for land capability. We made a number of assumptions about constraints, which, if changed, would alter the reported areas in the 'Findings' above.
Soil constraints to yield that occur on more than 3 million hectares include:
- soil water storage
- subsurface compaction
- acid or alkaline topsoil and subsoil
Constraints that cover from 1 to 3 million hectares include:
- wind erosion
- surface salinity
- surface soil structure decline.
The department did a major review of soil acidity (but not alkalinity) in 2013 and published the results in the report card on sustainable natural resource use in agriculture. The area of acid subsoil increased and acid topsoil decreased a little as a result of active liming programs.
Additional information on the standards used in this study are available in Land evaluation standards for land resource mapping : assessing land qualities and determining land capability in south-western Australia.