Farmers do not use the available technical information sufficiently well to secure maximum efficiency of the fertilizers they buy. Animal and crop wastes contain most of the N, P and K in British crops and these should be used in recycling more efficiently than at present. The amount of nitrogen involved in soil-crop-livestock cycles appears to be twice as much as is taken up by the crops and grass grown annually, implying that there are large losses from U.K. farms. Much loss by leaching and denitrification of nitrate, and by volatilization of ammonia, is inevitable with present practices. Much more P is applied to U.K. soils in fertilizers and animal wastes than crops contain. The surplus accumulates in soil and it seems that our farmers could save by purchasing substantially less phosphate than at present. The potassium supplied by fertilizers and animal wastes appears sufficient to maintain productivity. There is no evidence of waste by loss of K from the system. The efficiency of the plant nutrients involved in U.K. agriculture could be improved by greater care in choosing and using fertilizers, and in handling and applying animal wastes. Further improvement should result from more research on the farming cycles involving plant nutrients and particularly on nitrogen.