Phosphorus flow management of cropping system in Huainan, China, 1990-2012

The rapid increase in phosphorus (P) use in cropping has raised concerns regarding the conservation and environmental impact of P. This study applied a partial substance flow analysis (SFA) to establish a dynamic model to evaluate the changes in the P flows from 1990 to 2012 in the cropping system of Huainan City, a typical agricultural region in central China. Based on this model, the P flows, P losses, P accumulations, and phosphorus use efficiencies (PUEs) during this period were identified and quantified using data from official statistical databases, questionnaires, face-to-face interviews and published literature. The results indicate that the total P input, P output, and P stock increased during these years. The increased P input was mainly caused by the dramatic increasing application of chemical fertilizer and the large-scale livestock excrement, while the great amount of harvested grains increased the P output. With the high application of the P input, the P stock including stored straw and soil accumulation also grew during these years. The P losses and P accumulations generally increased, except for 1995-2005, as a result from the substantial decrease in the cropland. Consequently, the PUEs in these years were not promising and were as low as approximately 30%, with great straw accumulation and loss. Based on the observed P flow of the cropping system in Huainan, this study provides some recommendations for improving P management. The quantifiable science-based methods that were used in this study may be applied to improve the resource management efficiency of the cities/counties and the water quality of the surrounding area.