Phosphorus Runoff from Agricultural Land and Direct Fertilizer Effects
Murray R. Harta, Bert F. Quinb,* and M. Long Nguyenc
a School of Environment & Agriculture, University of Western Sydney (Hawkesbury Campus), Locked Bag 1797, Penrith South, DC NSW 1797, Australia [formerly Summit-Quinphos (NZ) Ltd]
b Summit-Quinphos (NZ) Ltd, PO Box 24-020, Auckland, New Zealand
c National Institute of Water & Atmospheric Research Ltd, PO Box 11-115, Hamilton, New Zealand
* Corresponding author ([email protected] )
J. Environ. Qual. 33:1954-1972 (2004).
Phosphorus (P) is one of the most important mineral nutrientsin agricultural systems, and along with nitrogen (N), is generallythe most limiting nutrient for plant production. Farming systemshave intensified greatly over time, and in recent years it hasbecome apparent that the concomitant increase in losses of Nand P from agricultural land is having a serious detrimentaleffect on water quality and the environment. The last two decadeshave seen a marked increase in research into the issues surroundingdiffuse losses of P to surface and ground water. This paperreviews this research, examining the issue of P forms in runoff,and highlighting the exceptions to some generally held assumptionsabout land use and P transport. In particular the review focuseson P losses associated with recent P fertilizer application,as opposed to organic manures, both on the amounts and the formsof P in runoff water. The effects of the physicochemical characteristicsof different forms of P fertilizer are explored, particularlyin relation to water solubility. Various means of mitigatingthe risk of loss of P are discussed. It is argued that the influenceof recent fertilizer applications is an under-researched area,yet may offer the most readily applicable opportunity to mitigateP losses by land users. This review highlights and discussessome options that have recently become available that may makea significant contribution to the task of sustainable managementof nutrient losses from agriculture.
Abbreviations: DAP, diammonium phosphate • DAPR, direct-application phosphate rock • DCP, dicalcium phosphate • DIP, dissolved inorganic phosphorus (usually equivalent to DRP) • DP, dissolved phosphorus (usually equivalent to TDP) • DRP, dissolved reactive phosphorus • PP, particulate phosphorus • SSP, single superphosphate • TDP, total dissolved phosphorus • TP, total phosphorus • TRP, total reactive phosphorus • TSP, triple superphosphate