The amount of water that must be applied annually to irrigated land is equivalent to between one foot and five feet of water covering the area cultivated, depending on the crop and the climate.

Leaving crop residue in the field can reduce moisture loss by the equivalent of an inch or more of rainfall annually, scientists say. Funk

few industries account for some two-thirds of all the demand: they are metals, chemicals and petroleum refining, pulp and paper manufacturing and food processing.

of water per year. In the wealthier nations, where the diet is commonly more than 3,000 calories per day, the agricultural water requirement is 400 cubic meters per year.

(Water of good quality can be used at least twice, directly or indirectly, before it becomes too brackish for further use.)

When irrigation is combined with other practices for increasing the efficiency of agriculture, such as the planting of improved crop varieties and the application of fertilizer and pesticide, yields can be increased by a factor of three or four.

holdings ; land-rental and taxation systems that destroy incentive; extreme difficulties in obtaining a farm loan promptly at a reasonable interest rate; poor marketing and storage systems; administrative inefficiency and corruption; the shortage of trained teachers and farm advisers; inadequate government services for agricultural research, educat

sustenance. Whether people get enough

The total amount of rain and snow falling on the earth each year is about 380 billion acre-feet: 300