Potential yield is the maximum yield possible given rainfall in the absence of any other constraints.

Estimates of potential wheat yield are obtained using the French & Schultz potential yield model:

where WUE is the abbreviation for Water Use Efficiency and Growing Season Rainfall is from April to October inclusive. Stored Soil Water at the start of the growing season is modelled for 10 different soil types. Users can choose WUE of 12 or 15 kg/ha/mm.

Growing season rainfall is composed of cumulative rainfall at the time the maps and users can choose from decile 3, 5 or 7 rainfall finish for the remainder of the growing season.

Evaporation is either 110 or 90 mm.

The potential yield model assumes that:

• crop emergence occurs in April or May,
• the timing of rainfall during the season does not negatively affect crop growth (there is no drying off), and
• there are no soil constraints that hinder root growth.
• For later sowing and emergence (for example in June) use evaporatation rate of 90 instead of 110 mm.

If any of these assumptions are not met, then potential yield could be considerably lower than shown in the maps.

Potential yield maps are produced at appropriate times during the growing season (usually from June to October).

For location-specific potential yield information, with selection of Evaporation and WUE, see the Potential yield tool