To explore whether cropping strategies using higher inputs are more water use efficient than lower input systems and to what extent this affects profit.

• The trial at Morawa compared a canola-wheat sequence to a wheat-on-wheat sequence with either high or low input levels. Low input had lower fertiliser, lower seed density and cheaper herbicide options. We also incorporated a comparison of a very early wheat cultivar (Zippy) to a medium maturity cultivar (Wyalkatchem).
• Water use by the crop was estimated from the sum of the in-season rainfall and the change in soil water between sowing and harvest. By estimating the amount of soil evaporation as one third of in-season rainfall, we determined the amount of water used by the plant as transpiration. The ratio of crop yield to transpiration is the transpiration efficiency of the crop which has a potential of around 20-22 mm/kg/ha.
• The yield of Zippy was more stable than that of Wyalkatchem, but the earlier maturity resulted in a substantial yield penalty. Zippy yielded around 2 t/ha each year whereas Wyalkatchem responded more in better years. The yield penalty associated with the earlier maturing variety was not offset by the higher input level. Higher input actually increased the variability in annual gross margins.
• So far Wyalkatchem has a substantially greater cumulative gross margin than Zippy and there is little difference between the high and low input strategies.