[Effect of reducing N and regulated fertilization on N loss from wheat-maize rotation system of farmland in Chao soil region of North China Plain].

O emission. Runoff loss was negligible. Among the treatments, N loss in farmer's practice treatment was the highest. Microbial fertilizer significantly reduced N loss through ammonia volatilization, but the loss through leaching was larger. In conclusion, with reduced N application compared with the farmer's practice, controlled release fertilizer and nitrification inhibitor could maintain crop yield and N uptake, and microbial fertilizer could ensure crop yield and N uptake for a longer plant growth period. The results suggested that inorganic N content in the 40-100 cm soil layer could be reduced in the soil by adding microbial fertilizer and nitrification inhibitors, and the amount of inorganic N was not reduced significantly by application of controlled release fertilizer. Several N reduction measures could reduce N loss. The microbial fertilizer treatment needed to be modified to reduce N leaching.