Estimation of groundwater recharge due to conservation agriculture practice

A review of groundwater recharge studies in Sub-Saharan Africa demonstrates a strong relationship between rainfall and recharge, but with considerable uncertainty due to significant impact of land cover and in particular land clearing and agriculture. This research project focuses on impacts of conservation agriculture (CA) practice on groundwater recharge. Conservation agriculture is being encouraged by governments over conventional methods in the understanding that CA practices such as minimum tillage, retention of crop residue and crop diversity improves crop resilience under dry conditions. However, there has been little consideration of the direct impact of such practices on groundwater. In this study, we setup three experimental sites in Zambia, Zimbabwe and Malawi to quantify recharge patterns under CA in comparison to conventional farming practice. Each site will be instrumented with soil moisture monitoring probes, a weather station, monitoring boreholes and electrical-resistivity tomography (ERT) equipment. Environmental isotopes and tracers (such as CFCs and SF6) and water chemistry will also be analysed. The monitoring will help to elucidate processes in the unsaturated zone around the plant root zone through to groundwater. Ultimately, this will help understand groundwater dynamics and fractioning below surface of CA fields