Water use efficiency in Western Australian cropping systems

Rotations and associated management practices in rainfed farming systems of southwest Australia have shifted towards intensified cropping. Survey data from 184 fields spanning 14 Mha were used to document water use efficiency (WUE) water-limited yield potential (WLYP) commercial crops crop sequences identify biophysical variables influencing WUE. WUE achieved wheat was 10.7 kg grain/ha.mm. Using a boundary function Ywl = 25 × (WU − 45), farmers 54% WLYP. Climate affected more than biotic variates, the highest latitude region having 9.0 grain/ha.mm, compared 11.8 grain/ha.mm for regions further south. Increased soil nitrogen fertiliser increased WUE, as did sowing earlier; keeping with southern earlier trebling usage since 1990. Wheat small amount after break or pasture (12.5 grain/ha.mm) grown (11.2 grain/ha.mm), due good weed root pathogen control, high application. However, declined 8.4 when three succession. Farmers continue improve inputs new technologies replacing some traditional functions pasture. pastures are still required within rotation maintain effects need be measured over several years.