Human Impact on Erodable Phosphorus and Eutrophication: A Global Perspective

Abstract

Human actions—mining phosphorus (P) and transporting it in fertilizers, animal feeds, agricultural crops, and other products—are altering the global P cycle, causing P to accumulate in some of the world's soil. Increasing P levels in the soil elevate the potential P runoff to aquatic ecosystems (Fluck et al. 1992, NRC 1993, USEPA 1996). Using a global budget approach, we estimate the increase in net P storage in terrestrial and freshwater ecosystems to be at least 75% greater than preindustrial levels of storage. We calculated an agricultural mass balance (budget), which indicated that a large portion of this P accumulation occurs in agricultural soils. Separate P budgets of the agricultural areas of developing and developed countries show that the rate of P accumulation is decreasing in developed nations but increasing in developing nations.