Keywords: Phosphorus, resources, recycling, efficiency.

Phosphorus (P) is one of the elements essential for plant growth, for which there are no substitutes. An inadequate supply of plant-available phosphorus limits crop yields while an over-supply is wasteful and environmentally detrimental. World reserves of economically-exploitable phosphate rock are limited. The cost of processing phosphate rock is increasing as the richest deposits become depleted and regulatory requirements concerning impurities present in the rock become more stringent. Recycling of phosphorus has serious limitations. Genetic engineering could improve phosphorus use efficiency if it is socially and economically acceptable. Most of the phosphorus applied to a crop is fixed in the soil. There is evidence that the soil-fixed phosphorus becomes available to subsequent crops but over a long period of time.

P Heffer, M P R Prud'homme and B Muirheid, International Fertilizer Industry Association (IFA), Paris, France; and
K F Isherwood, Consultant, Paris, France.

32 pages, 4 figures, 5 tables, 17 references.