Water Use Efficiency in Agriculture: The Role of Nuclear and Isotopic Techniques

1. Agriculture is the predominant user (75-80%) of the available freshwater resource in many parts of the world. At present most of the water used to grow crops is derived from rainfed soil moisture, with non-irrigated agriculture accounting for some 60% of production in developing countries. Although irrigation provides only 10% of agricultural water use and covers just around 20% of the cropland, it can vastly increase crop yields, improve food security and contribute 40% of total food production since the productivity of irrigated land is three times higher than that of rainfed land. The Food and Agriculture Organization (FAO) predicts a net expansion of irrigated land of some 45 million hectares in 93 developing countries (for a total of 242 million hectares in 2030) and project that agricultural water withdrawals will increase by approximately 14% during 2000-2030 to meet food demand1.