Nitrogen recommendation for dryland winter wheat by monitoring nitrate in 1 m soil and based on nitrogen balance

To achieve the purpose of increasing crop yield, improvement of soil fertility by balancing nitrogen (N) output from soil, and preventing N leaching due to too fertilizer N residue in soil on dryland, recommendation of N fertilizer based on monitoring nitrate N residual in 1 m soil layer (RNBM) and the balance of soil N input and output was studied, and effects of this N fertilizer recommendation method were tested by twoyear field experiments on six fields with different soil fertility in Yongshou Shaanxi. Obtained results showed that, compared to the farmers practice (FP), the RNBM method reduced the nitrogen application rate by 41.2%, but increased the grain yield of winter wheat by 17.0%, fertilizer N partial factor productivity by 188.3%, and the output/cost ratio (OCR) by 28.9%. Nitrate N residual in 1 m soil layer was 37.0 kg/ha for the RNBM method at harvest time, which was 66.9% lower than that of 112.1 kg/ha for the FP. After intensively rainy summer fallow, nitrate N residual in 1 m soil layer was increased by 15.4 kg/ha for the RNBM method, while that was decreased by 27.4 kg/ha for the FP treatment. These results indicated that N fertilization recommendation based on monitoring the nitrate N residue in 1 m soil layer and soil N balance was able to effectively increase crop yield, reduce N input and fertilizer cost, improve N efficiency, and minimize nitrate N residue and leaching in dryland soil.