Simulated Study on Phosphorus Leaching of Typical Soils in Danjiang Reservoir Area

Phosphorus (P) is an essential element for plant growth and a key element for eutrophication of water bodies as well. The P loss from agricultural soils not only leads to a decrease in the efficiency of fertilizers, but also gives rise to the eutrophication of surface water. In this paper, simulated test with soil columns in laboratory was conducted to study the leaching characteristic of P fertilizer in typical soils from Danjiang reservoir area in Hubei province. The results revealed that P fertilizer application had significant influences on phosphorus in leachate. Both accumulative leaching amount and concentration of MRP (Molybdate reactive phosphorus) in leachate increased with P fertilizer applied. The peak concentration of MRP in leachate was obtained after 3 or 4 times of leaching, and the MRP concentration declined gradually and became stable at last as the leaching continued. The clay content in soil also influenced the concentration of MRP, especially in soil with higher clay content. This test also indicated that the accumulative amount of MRP in leachate was in the sequence: limestone soilpurple soilyellow brown soil, which implied that the limestone soil had high potential of P leaching while low potential for the yellow brown soil.