Water use by lucerne and effect on crops in the Victorian Wimmera

Abstract

The effect of the perennial legume lucerne on the soil water regime of a farming system in the Victorian Wimmera was investigated by a combination of direct field measurements and the use of simulation modelling. In the field, soil profiles under lucerne-based pastures (also containing annual medic and Wimmera ryegrass) remained consistently drier throughout the year compared with continuous annual cropping. The amount of plant-available soil water (0-2.0 m) after 3-4 years of lucerne pasture was on average 48 mm less than after annual crops (wheat, field pea), most of which (81%) was extracted at depth (1.0-2.0 m). A wheat simulation study evaluated yield responses post-lucerne under a rang..