ABSTRACT
Water is essential for maintaining an adequate food supply and a productive environment for the human population, plants, animals, and microbes on the Earth. Per capita food supplies (cereal grains) have been decreasing for nearly 20 years (declined 17%), in part because of shortages of freshwater, cropland, and the concurrent increase in human numbers (FAO, 1961-2002). Shortages in food supplies have in part contributed to more than 3 billion malnourished people in the world (WHO, 2004a). Two of the most serious malnutrition problems include iron defi ciency affecting 2 billion people and protein/calorie defi ciencies affecting nearly 800 million people (WHO, 2002, 2004b). The iron defi ciency and protein/calorie defi ciency each result in about 0.8 million deaths each year (WHO, 2002). Humans obtain all their nutrients from crops and livestock and these nutrient sources require water, land, and energy for production (Pimentel et al., 2004).
