The in-field rainwater harvesting technique (IRWH) has helped a thousand households in South Africa’s Eastern Cape transform their backyards into productive gardens filled with vegetables and crops. Since its introduction in 2001, IRWH has helped the households attain profits from between 34-50%. The technique was developed by researchers from the Institute for Soil, Climate and Water (ISCW) of the Agricultural Research Council (ARC) of South Africa. IRWH increases yields on high drought risk clay soils by combining the advantages of water harvesting, no-till, basin tillage and mulching.

The technique entails promoting runoff on a 2-m wide strip between alternate crop rows, and storing the runoff water in the basins. Water collected this way infiltrates deep into the soil, preventing evaporation. Various combinations of organic material or stones can be applied to the basins and the runoff area to promote water conservation. Mulch in the basins and the 2-m wide runoff strip helps to suppress evaporation, while it also reduces or suppresses soil movement. Fully-grown crops benefit during dry seasons from the water stored in the soil volume underneath the runoff area, which is unavailable early in the growing season. After the basins have been constructed, no-till is applied to the land as a whole. Due to the absence of cultivation a crust soon develops on the runoff strip.

More information: Botha, J.J. … [et al.] (2004). Evaluating the sustainability of the in-field rainwater harvesting crop production system. Paper submitted to the ICID - FAO International Workshop on Water Harvesting and Sustainable Agriculture, Moscow, 7 September 2004. URL: http://www.fao.org/ag/agl/aglw/wh/docs/botha.doc

Contact: J.J. Botha, ARC - Institute for Soil, Climate and Water, South Africa, botha@glen.agric.za, http://www.arc.agric.za/institutes/iscw/main/projects/waterharvest.htm

Source: SABC News, 7 Dec 2005

Tags: water and livelihoods, water collection