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Agricultural Chemicals in Relation to Environmental Quality: Chemical Fertilizers, Present and Future¹

ABSTRACT

Unfertilized soils no longer can provide the food necessary to meet the needs of expanding populations, Fertilizer use has increased dramatically in recent years; however, intensity of use varies greatly in different parts of the world, in various sections of the USA, and with the kind of crop grown. In the USA, fertilizers have accounted for over 50% of the increase in crop production since 1940, and farmers have substituted fertilizers for land and other inputs. However, considerable controversy has developed in recent years over the role of fertilizers in pollution of natural waters. Increased nitrate and phosphate levels in waters are cited by ecologists as proof of contamination by fertilizers, but this is contested by many agriculturists. Examination by competent reviewers of the limited data available so far indicates that losses of fertilizer nutrients into surface and groundwaters may be minimal under most situations. Should situations be found where fertilizers do contribute appreciably to water pollution, corrective steps may have to be taken. There are a number of ways to minimize losses without sacrificing the important benefits gained from fertilizers. These include carefully tailoring rates and times of nitrogen application to better fit the needs of the growing crop, greater care in irrigation, use of slow-release nitrogen fertilizers, and wider application of selected soil conservation practices to control surface losses of both nitrates and phosphates.

¹ Paper presented Dec. 28–29, 1970, in Chicago, Ill., at the American Association for the Advancement of Science Section "O" Agriculture Symposium on "Agriculture and the Quality of the Environment in the Seventies."

² Manager, Office of Agricultural & Chemical Development, Tennessee Valley Authority, Muscle Shoals, Ala.