Characteristics of nutrient runoff losses in farmland of Nansi Lake basin under different fertilization patterns

The optimized fertilization patterns are important to reduce nutrient runoff losses and improve lake water quality. The seasonal changes of N and P runoff losses were monitored in a wheat-maize rotation system in Nansi lake basin in temperate region of North China. The results show that organic materials mixed with soil or covering on soil surface could effectively reduce runoff water amount, and bedload loss is not directly related to runoff water amount. The trends of contents of inorganic nitrogen, total nitrogen, dissolved phosphorus and total phosphorus are varied at different growth stages of maize caused by distribution and intensity of the precipitation at the experimental site, and the contents are significantly different in each fertilization treatment as affected by amounts, varieties and types of fertilizers. N losses through runoff are mainly in NO3--N form (NO3--N runoff loss accounts for 82.9%90.8% of the total), and the dissolved phosphorus loss and particulate phosphorus loss are about a half of total phosphorus loss. Total nitrogen loss is up to 11.89 kg/ha in FP (People traditional fertilization) treatment throughout the maizes season. NO3--N concentration is a potential threat to groundwater quality. The balanced fertilization, N-controlled release fertilizer, organic fertilizer and straw returned to soil could significantly reduce losses of inorganic nitrogen, totalnitrogen, and phosphorus compared to the FP treatment. Considering the production of maize (Maize yields are increased about 7.7%, 5.9%, 3.6% and 1.5% in above four treatments compared to the FP treatment) with reducing water pollution caused by nutrient runoff losses, the above four fertilization patterns could be used in the farmland of Nansi Lake basin, in which the effect of N-controlled release fertilizer is better.