The effects of conservation tillage on potential groundwater recharge

Abstract

Measurements of soil water and chloride made in a 10-year-old tillage experiment in north-western Victoria, Australia, at Dooen, were used to calculate the effect of different tillage methods of fallowing in a fallow-wheat rotation on drainage below the root zone and hence potential recharge to groundwater. The soil type was a grey cracking clay (chromic vertisol) and the tillage methods included: stubble-retained zero-tilled fallows (SRNT), stubble-retained subsurface tilled fallow (SRST) and conventional fallow (no stubble fully tilled)-wheat rotation (NSCT). Calculations of potential recharge rate over the 10 year period of the tillage experiment in two fields showed between 18.5 and 18.6 mm year −1 additional recharge occurring owing to SRNT fallowing on this soil compared with NSCT fallow. The SRST fallow, which disturbs the soil below the surface (5–15 cm) without significant inversion, showed significantly less potential recharge of 2.2–3.8 mm year −1 compared with NSCT fallow. Both SRST and NSCT fallow appear to have similar water flux rates.