控氮对黄壤坡耕地小麦-玉米轮作土壤氮素分布特征的影响

Effects of Nitrogen Control on Soil Nitrogen and Crop Yield of Wheat and Maize Crop Rotation System in Sloping Cropland with Yellow Soil

【目的】为摸清氮肥与作物产量之间的关系,明确冬小麦/夏玉米轮作体系氮肥投入阈值范围,从污染源头控制氮肥的迁移、流失,提高氮肥吸收利用效率和减少环境污染提供理论依据。【方法】采用大田小区试验,设置不施肥对照、优化减氮25%、优化施肥、优化增氮125%、优化增氮150%、优化增氮200%等6个处理,研究黄壤坡耕地土壤中硝态氮、铵态氮及可溶性氮累积、迁移规律及作物产量的影响。【结果】施氮均能提高土壤硝态氮、铵态氮和可溶性氮的含量及其累积量;各处理硝态氮、铵态氮的垂直迁移趋势不同,且土壤硝态氮、铵态氮主要集中在0～40 cm土层,分别占总硝态氮含量的37.3%～55.1%、29.3%～45.1%,2种作物可溶性氮的垂直迁移趋势基本一致;与优化施肥相比,优化增氮处理对硝态氮、铵态氮向土壤深层迁移趋势影响作用明显,但对土壤可溶性氮向土壤深层迁移趋势影响不明显;施肥各处理的硝态氮、铵态氮和可溶性氮含量及小麦和玉米产量较不施肥处理均有显著增加。【结论】合理施用氮肥可降低土壤硝态氮、铵态氮和可溶性氮及提高作物产量。优化减氮(OPT-N)措施较其他施肥处理的经济效益和环境效益有显著提高,是值得推荐的施氮措施。

【Objective】This paper aims to understand the relationship between nitrogen fertilizer and crop yield,the threshold range of nitrogen fertilizer input in winter wheat/summer maize rotation system was confirmed,and the migration and loss of nitrogen fertilizer were controlled from the origin,so as to provide the theoretical basis for the improvement of nitrogen fertilizer absorption and utilization efficiency,as well as environmental pollution reduction.【Method】A field plot experiment was conducted to explore the accumulation and migration of nitrate nitrogen,ammonium nitrogen and soluble nitrogen,as well as crop yield in sloping cropland with yellow soil.The treatments were set as follows：no fertilization treatment was set as control（CK）,the other five treatments were optimized nitrogen reduction by 25 %（OPT-N）,optimized fertilization（OPT）,optimized nitrogen increased by 125 %（OPT＋N1）,150 %（OPT＋N2） and 200 %（OPT＋N3）,respectively.【Result】Applying nitrogen can increase the contents and accumulation of nitrate nitrogen,ammonium nitrogen and soluble nitrogen in soil.The vertical migration trends of nitrate and ammonium nitrogen were different,and were mainly concentrated in 0-40 cm,which accounted for 37.3 %-55.1 % and 29.3 %-45.1 % of total nitrate nitrogen,respectively.However,the vertical migration trends of soluble nitrogen in the two crops were similar.Compared with the optimal fertilization,the optimized nitrogen increasing treatment has obvious influence on the migration trend of nitrate nitrogen and ammonium nitrogen to the deep soil,but has no obvious influence on the migration trend of soil soluble nitrogen to the deep soil.Compared with the control,the contents of nitrate nitrogen,ammonium nitrogen and soluble nitrogen,as well as wheat and maize yields all significantly increased.【Conclusion】Reasonable application of nitrogen fertilizer would reduce soil nitrate,ammonium and soluble nitrogen contents,but increase crop yield.The economic and environmental benefits of optimized nitrification（opt-n） are significantly higher than others,which could be a recommended measure for nitrogen application.