[Distribution of Phosphorus in Soil Profiles after Continuous Application of Different Fertilizers]

This study clarifies the distribution and migration characteristics of phosphorus in the soil profile and discusses the phosphorus load of farmland after continuous application of different organic fertilizers. The distribution and migration characteristics of phosphorus in soil profiles were studied through a field experiment lasting four consecutive years. The results showed that total phosphorus and Olsen-P are mainly accumulated in the soil surface, and their contents decrease with the deepening of soil depth after the continuous application of different fertilizers. With a four-year application of higher levels of organic fertilizer, the total phosphorus was found to migrate into the 15-30 cm soil layer. Olsen-P was found to migrate into the 60-90 cm soil layer under higher levels of pig manure. The ratio of available phosphorus to total phosphorus in the soil surface increased, and there were significant differences after the application of different amounts of organic fertilizers. The amount of Olsen-P as a proportion of total phosphorus in the soil profile decreased as pig manure treatment > chicken manure treatment > sludge treatment > phosphate fertilizer treatment. After the application of chicken manure, pig manure, sludge, and phosphate fertilizer, the value of Olsen-P in the soil surface increased with an increase in phosphorus input and then remained stable. When applying the same phosphorus onto the soil, the contribution of different organic fertilizers to Olsen-P in the surface soil was quite different. The bioavailability and mobility of phosphorus from pig manure was significantly higher than that of chicken manure, sludge, and phosphate fertilizer.