Characteristics of Phosphorus Loss from Organic Farming and Forestry Land under Simulated Rainfall in the Mountainous Areas of Western Anhui

The representative vegetable plots (Allium hookeri) and economic forest lands (Cuilan Tea) were selected as the studied objects to explore the characteristics of phosphorus loss in surface and subsurface runoff from organic farming and forestry in the western Anhui Mountains. Rainfall experiments were carried out by simulating small, medium, and large rainfall intensities (0.6, 0.9, and 1.5 mm/min, respectively) in the field. The results show that the range of phosphorus loss in the surface runoff from organic vegetable plots and tea plots accounts for 52.5%-69.5% and 56%-71.7% of the total phosphorus, respectively. The proportion of phosphorus loss increases with the increase in rainfall intensity. Moreover, vegetation coverage and tillage methods (soil looseness) affect the difference in phosphorus loss in agricultural and forestry land. Particulate phosphorus (PP) is the main form of phosphorus loss in surface runoff in this area. Dissolved phosphorus (DP) is the main form of phosphorus loss in the subsurface runoff, and the main DP is dissolved inorganic phosphorus. Moreover, phosphorus loss in subsurface runoff is still high. This study provided a reference for the accounting of organic farming and forestry pollution sources and the subsequent prevention and control of non-point source pollution.