Water Productivity in Rainfed Agriculture - UNESCO-IHE PhD Thesis (Paperback)

The challenge of water scarcity as a result of insufficient seasonal rainfall and dry spell occurrences during cropping seasons is compounded by inefficient agricultural practices by smallholder farmers where insignificant soil and water conservation efforts are applied. The hypothesis of this research is that many of the past research efforts have taken a fragmented approach to deal with the challenges facing subsistence farmers in rainfed systems. The research has been conducted in the semi-arid Makanya catchment of northern Tanzania and has successfully applied different analytical techniques to better understand soil and water interactions at field scale. It has been demonstrated that there is indeed scope to increase crop water productivity provided the local farmers adopt more efficient cultivation techniques. Substantial yield increases occur as a result of diverting runoff and these further improve when other techniques such as ripping, application of manure and cover cropping are introduced. This confirms that no single solution exists to solve the problem of low yields in rainfed farming systems. However, even with these promising results, the research has shown that there is room to further improve the efficiency of crop water use through improvement in research approaches and exploration of better techniques.