Keywords: Recycling, plant nutrients, phosphorus, fertilizers, biosolids, manures, nutrient use efficiency, energy use efficiency,
legislation on recycling.

The recycling of plant nutrients in agriculture through the use of organic manures, biosolids and other organic wastes is discussed with special reference to phosphorus (P) and its efficient use in crop production. The benefits and limitations of different approaches to recycling are developed from a historical overview to the present day to show that waste disposal can be replaced by the effective and efficient use of wastes as part of recycling nutrients. This is especially important for P because of the limited global supply of this element, an essential constituent of all living cells. Public perception and acceptance of some aspects of recycling plant nutrients will need to be addressed with urgency. Legislation on the use of various soil amendments will need to be unified, certainly within the enlarged European Community, and preferably globally. Suggestions are made for developing a more unified approach to legislation governing the agricultural use of materials currently considered wastes, and secondary and co-products from industrial processes so that these materials can be used with advantage to conserve resources.

A E Johnston, Lawes Trust Senior Fellow, Soil Science Department, Rothamsted Research, Harpenden, Herts., AL5 2JQ, UK.

32 pages, 1 figure, 1 table, 66 references.