ABSTRACT
Cereals directly supplied around 57% of calories in the global human diet in 2000 (Food and Agriculture Organization [FAO], 2000b). The meat and dairy foods produced from animals that consumed 33% of world cereals provide additional calories. Together, wheat (Triticum aestivum), rice (Oryza
sativa), and maize (Zea mays) make up approximately 85% of the world’s cereal production. Wheat and rice are by far the most widely consumed cereals in the world, while maize is important for both direct and indirect human consumption. Approximately 67% of maize production is used as animal fodder. The FAO (1996) reported that 48% of cereal production in developing countries (excluding China) came from irrigated lands. This is in contrast to many developed countries where cereals, particularly wheat and maize, are largely grown without irrigation. It is estimated that 60% of wheat produced in developing countries is irrigated, while only 7% of wheat and 15% of maize are irrigated in the United States (U.S. Department of Agriculture, 1997). Other major cereal-producing areas such as Canada, Australia, and Europe are mainly nonirrigated.
