Water productivity and food security: considering more carefully the farm-level perspective

With the increasing demands on water resources in many areas, many authors are calling for increases in water productivity in agriculture to ensure sufficient food production in the future. While compelling at first glance, the notion of increasing water productivity is not supported by an underlying economic rationale and is not necessarily consistent with the goals of individual farmers regarding net revenue or subsistence production. Water productivity, as defined in the literature, is a ratio describing the average amount of output or value associated with the amount of water applied or transpired in crop production. As such, the ratio is not a sufficient indicator of economic efficiency and cannot be relied on to determine desirable adjustments in regional water allocations or in farm-level irrigation strategies. I describe the shortcomings of water productivity as an indicator of optimal water use, with a focus on farm-level decisions regarding crop production and irrigation. I note also the importance of considering more carefully the full set of inputs that contribute to crop production, and the risk and uncertainty that influence farm-level decisions. Water productivity does not address these inherent characteristics of agricultural production, which must be considered when evaluating policies and investments to enhance rural livelihoods and ensure food security.