Effects of three in-field water harvesting technologies on soil water content and maize yields in a semi-arid region of Zimbabwe

Abstract

Climate change and recurring mid-season dry spells have resulted in perennial droughts and poor yields in most smallholder farming areas located in marginal arid to semi-arid lands (ASAL) of Zimbabwe where they are dependent on rainwater for agricultural crop production. One approach that can be used to adapt to changing climatic pattern is in-field water harvesting. This study evaluated the soil profile water content and maize yields of 3 infield water harvesting technologies namely infiltration pits (IF), fanya juus (FJ) and contour ridges with cross ties (CRCT) in comparison to standard contour ridges (SC). The three systems are currently the focus of extension recommendations for water conservation in semi-arid regions of the country. Soil water content was measured on a regular basis using gravimetric methods at locations upslope and down slope of each structure. The average volumetric water content was signifcantly different between treatments, and it varied with increasing distance from the water harvesting structures. The average profile soil moisture content, over the three seasons were 8.3, 8.2, 8.1 and 7.8% for CRCT, FJ, IF and SC repectively. CRCT, FJ and IF retained more water for a greater distance from the harvesting structures compared to the SC. Maize yields were significantly higher in the water harvesting technologies compared to SC. Maize yields were 1196, 1164, 1250 and 749 kg ha−1 for CRCT, FJ, IF and SC respectively. There as a good correlation between water content and maize yields (R2 = 0.80). It was concluded that improved water harvesting structures when compared to SC have the potential to increase maize yields in areas with water shortages, hence they can be a useful strategy for climate change adaptation.