"Update of May 1977 issue." Jan. 1979. Includes bibliographical references.

The primary soil nutrients that are needed to assure high yields per acre from arable lands are nitrogen, phosphorus, and potassium. These elements are applied to the soil as they are depleted by crops. There is no substitute for the unique nutritive element phosphorus in agriculture, and the only source of phosphorus is phosphate rock. Phosphorus cannot be recycled or recovered from secondary sources. This Bureau of Mines report presents comprehensive data on phosphate including industry structure, reserves-resources, technology, supply-demand relationships, byproducts and coproducts, economic factors and problems, government programs and legislation, strategic considerations, operating factors and problems, and outlook to 2000.