Keywords: Phosphorus, fertiliser, sustainable management, agriculture, eutrophication.
Current strategies of phosphorus (P) fertiliser use are based on feeding the soil to feed the plant. There are large inefficiencies associated with this strategy due to the immobilisation of fertiliser P by soil, the limited volume of the soil that roots can explore, the influence of environmental factors that can limit the diffusion of P from the soil to the root and the uncertainties associated with soil sampling, analysis and interpretation. These inefficiencies are not sustainable if the finite reserves of rock phosphate are to be preserved for future generations and if environmental damage (eutrophication) associated with soil legacy P accumulation is to be reduced. Fertiliser is also the biggest variable cost in crop production so it is worth investing in ways to use less. We therefore argue for a new strategy that relies far less on maintaining a store of soil available P and more on innovations to maximise direct recovery of P by the plant, improve agricultural P use efficiency and reduce dependence on RP-derived fertilisers. This strategy considers maximising crop recovery of P from soil and fertiliser separately and introduces three key innovations to achieve this: (i) minimise crop P requirements, (ii) maximise root recovery of accumulated soil P, and (iii) target fertiliser more precisely to meet critical growth phases (e.g. early crop establishment) and with as complete P recovery as possible. These innovations together provide a win-win solution to improving the sustainability of P use and management because they would not only lead to lower fertiliser P inputs, growing costs and help preserve RP resources, but also help to reduce P excretion rates from livestock, lessen local surplus P accumulation in soils and P losses in land runoff to watercourses lowering eutrophication risk. Recycled and recovered P could also more effectively substitute for inorganic fertiliser, raise background soil P fertility and improve soil quality in the longer term, but their use is currently constrained by economics, spatial disconnects and variability in quality. The challenges this new approach present are explored within the context of sustainable intensification, resource conservation and protection of the environment.
P J A Withers1, R Sylvester-Bradley2 and D L Jones1.
1 School of Environment, Natural Resources and Geography, Bangor University, Bangor LL57 2UW, UK.
2 ADAS UK Ltd., Battlegate Road, Boxworth, Cambridge, CB23 4NN, UK.
31 pages, 5 figures, 152 references.