Rainwater harvesting for sustainable agriculture in communal lands of Zimbabwe

The study was carried out at three sites in Communal Lands of Zimbabwe namely, Mudzi (Natural Region V), Gutu (Natural Region IV) and Chivi (Natural Region V). These areas have marginal rainfall in terms of quantities (below 500mm per year) and distribution with a normal rainfall year coming once in every five years. Four tillage treatments were experimented on in the three sites. These were tied ridges, infiltration pits, fanya juus and the conventional ploughing on the flat. The tillage treatments were paired at farm level for easy management considering that farmers were participating in the research trials. The conventional tillage technique was used as control. The objective of the study was to evaluate and recommend rainwater harvesting techniques that ensure effective capture and utilization of rainfall for sustainable crop production. This was achieved through monitoring residual moisture, after every rainfall shower, in the different tillage treatments. Monitoring of residual moisture was done, up to a depth of 30cm, using a theta-probe. Yields of maize from the different tillage treatments were determined. Farmers also carried out their own evaluation of the treatments at mid-season and at the end of the season. In addition the researchers tested dissemination techniques that ensured maximum adoption of rainwater harvesting techniques. Tied ridges were ranked best by both the stakeholders' evaluation and the theta (theta)-probe in retaining moisture compared to all the other treatments in the season under consideration. The farmers who practiced tied ridges realized yields of about 3t/ha compared to conventional tillage treatments whose yields were about 1.5t/ha. Yields were statistically significantly different for the different treatments. The recommendation was for the farmers to adopt the tied ridges in areas that receive marginal rainfall and experience mid-season droughts. Lead farmers should educate others on the advantages of the tillage treatments. (C) 2004 Published by Elsevier Ltd.