Assessment of phosphorus loss under different tillage methods in Hetao Agricultural Irrigation Areas

To assess the phosphorus loss under different crops cultivations in farmland, soil samplings were taken in four typical crop types’ fields in five layers of 0-100 cm. Based on the isothermal methane-adsorbing experiments, SPSS software was applied to analyze the results statistically. The phosphorus loss potential was evaluated and the influence factors were discussed in this paper. The results revealed that the sorption characteristics of all the soil samples in the study area could be described by Langmiur and Freundich equations, and the Langmiur equation fit better. The soil in wheat field showed better sorption of phosphorus than that of other crops. The soil samples of intercropping field demonstrated poor sorption capacity. The phosphorus sorption of the top soil in the different crop fields showed few variations. Compared with the phosphorus sorption of the deeper layers, the top soil was prone to lose along with farmland drainage except in the intercropping field, where the phosphorus loss with seepage vertically into groundwater was the preferential way. Phosphorus sorption index (PSI) was another effective parameter to assess the phosphorus loss potential except for the theoretically maximum sorption capacity Qm and the equilibrium phosphorus concentration at zero sorption(EPC0). The conclusions of this paper can provide scientific references for appropriate scheduling on efficient fertilization, irrigation, and non-point source pollution control.