Water Prod - Chap 09

Considering the persistently growing pressure on finite freshwater and soil resources, it becomes increasingly clear that the challenge of feeding tomorrow’s world population is, to a large extent, about improved water productivity within present land use. Rain-fed agriculture plays a critical role in this respect. Eighty per cent of the agricultural land worldwide is under rain-fed agriculture, with generally low yield levels and high on-farm water losses. This suggests a significant window of opportunity for improvements. Ninety-five per cent of current population growth occurs in developing countries and a significant proportion of these people still depend on a predominantly rain-fed-based rural economy. This chapter presents the agrohydrological rationale for focusing on water productivity in rain-fed agriculture, identifies key management challenges in attempts to upgrade rain-fed agriculture and presents a set of field experiences on system options for increased water productivity in smallholder farming in drought-prone environments. Implications for watershed management are discussed, and the links between water productivity for food and securing an adequate flow of water to sustain ecosystem services are briefly analysed. The focus is on sub-Saharan Africa, which faces the largest food-deficit and water-scarcity challenges. The chapter shows that there are no agrohydrological limitations to doubling or even quadrupling onfarm staple-food yields, even in drought-prone environments, by producing more ‘crop per drop’ of rain. Field evidence is presented suggesting that meteorological dry spells are an important cause of low yield levels. It is hypothesized that these dry spells constitute a core driving force behind farmers’ risk-aversion strategies. Risk aversion also contributes to the urgent soil-fertility deficits resulting from insignificant investments in fertilizers. For many smallholder farmers in the semi-arid tropics, it is simply not