基于土壤氮素平衡的旱地冬小麦监控施氮

提高作物产量，平衡土壤氮素携出，培肥土壤，避免过多肥料氮残留造成淋溶，是旱地作物施氮的主要目标。本研究通过1 m土层硝态氮监控，从土壤氮素的输入和携出平衡计算氮肥用量，并在陕西永寿不同肥力水平的地块上连续2年布置田间试验进行验证。结果表明，与习惯施肥相比，监控施肥的氮肥用量减少41.2%，籽粒平均增产17.0%，氮肥偏生产力平均增加188.3%，产投比平均提高28.9%。监控施肥处理在收获期1 m土层硝态氮残留量平均为37.0 kg/hm2，较习惯施肥（112.1 kg/hm2）降低66.9%。经过降雨集中的夏季休闲期后，监控施肥处理1 m土层的硝态氮平均增加15.4 kg/hm2，习惯施肥则减少27.4 kg/hm2。这说明通过对1 m土层硝态氮的监控，依据土壤养分平衡，计算旱地小麦氮肥用量，可以提高产量，有效减少氮肥投入，降低成本，增加农户收入，提高氮肥效率，减少旱地土壤硝态氮残留和淋溶。

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 farmer’s 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.