POTENTIAL GROUNDWATER RECHARGE FROM FALLOWING IN NORTH-WEST VICTORIA,AUSTRALIA

Long-term rotation experiments in the Wimmera and Mallee regions of no rth-west Victoria, Australia, were used to measure soil water, matric potential and chloride profiles to calculate the effect of fallowing o n potential recharge to groundwater. Two common but distinct soil type s were investigated, a grey self-mulching clay (chromic vertisol) and a brown solonised soil (calcic xerosol).Significant differences occurr ed between fallow (18 months duration) and non-fallow cropping rotatio ns in soil water content, matric potential and chloride within and bel ow the root zone in profiles at both sites, Calculations of potential recharge show that fallowing one year in three, compared with continuo us cropping on the vertisol, has increased the downward flux of water by 6 mm year(-1) over a 72 year period. On the xerosol, over an 8 year period, potential recharge estimates ranged from 11 to 56 mm year(-1) from fallowing one year in three and every second year, respectively, compared with a pasture-wheat rotation.