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Feed the Crop Not the Soil: Rethinking Phosphorus Management in the Food Chain Paul J. A. Withers,*,† Roger Sylvester-Bradley,‡ Davey L. Jones,† John R. Healey,† and Peter J. Talboys† †
School of Environment, Natural Resources & Geography, Bangor University, Bangor, Gwynedd LL57 2UW, United Kingdom ADAS UK Ltd, Boxworth, Cambridgeshire CB3 8NN, United Kingdom recognized that “the undernourishment of the soil is at the root of all”.1 Research has shown that crops will not grow optimally, or utilize other nutrients efficiently, if the supply of P is inadequate,2 and over 80% of the rock phosphate (RP) currently mined each year is now used for fertilizer manufacture.3 Together with other agronomic advances, their use has undoubtedly contributed to the green revolution and the success of western agriculture, but at a large cost to the wider environment. High global consumption rates of P fertilizer are depleting the finite reserves of good quality RP, and surpluses of P in agricultural systems are contributing to widespread eutrophication.4 Phosphorus fertilizers are also a source of harmful inputs of metals, especially cadmium (Cd) and uranium (U), to agricultural soils, and the manufacturing process leaves large stockpiles of radioactive phosphogypsum. Heavily fertilized soils are ecologically less diverse with loss of soil function.5 There are even reports that excess P in the human diet resulting from increasing meat consumption and use of food additives may be compromising human health.6 A Society relies heavily on inorganic phosphorus (P) compounds major question for society is whether our continued dependthroughout its food chain. This dependency is not only very ence on manufactured P is environmentally sustainable and inefficient and increasingly costly but is depleting finite global whether the general public need to become more connected reserves of rock phosphate. It has also left a legacy of P with its food production, food processing and waste handling accumulation in soils, sediments and wastes that is leaking into systems and their impacts on global resources and the our surface waters and contributing to widespread eutrophicaenvironment? tion. We argue for a new, more precise but more challenging The manufacture and use of P fertilizers is extremely wasteful paradigm in P fertilizer management that seeks to develop more and inefficient. This inefficiency is evident along all parts of the sustainable food chains that maintain P availability to crops and P supply chain, from the mining of RP to the field application livestock but with reduced amounts of imported mineral P and of the manufactured product to current patterns of human improved soil function. This new strategy requires greater consumption.7 Dawson and Hilton3 estimated that the annual public awareness of the environmental consequences of dietary intake of dietary P by the current human population of ca. 7 choice, better understanding of soil−plant−animal P dynamics, billion is only between 1.7 and 3.7 Mt yr−1 compared with an increased recovery of both used P and unutilized legacy soil P, annual input of ca. 20 Mt of mined P into global agriculture; an and new innovative technologies to improve fertilizer P efficiency of
