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为探求能有效改良土壤理化性状并降低农田面源氮素污染的农艺措施,采用田间试验方法,研究了洱海流域不同农艺措施对耕层土壤水稳性团聚体、有机质组分和土壤硝态氮含量的影响。结果表明,免耕覆盖和增施有机肥能明显提高耕层土壤中>0.25 mm粒径水稳性团聚体的数量,分别达82.31%和81.1%,平均比习惯施肥(79.00%)和空白处理(76.53%)提高了4.19%和5.97%;两者均能增加耕层土壤有机质含量,并使耕层土壤中C/N比值明显提高;免耕覆盖和有机倍增处理的溶解性有机氮(DON)含量显著高于习惯施肥,分别提高了28.20%和28.68%;两者的微生物量碳(MBC)含量较习惯施肥分别增加了74.77%和68.54%,微生物量氮增加了32.43%和20.94%;并能明显降低0~20 cm土壤硝态氮残留,较习惯施肥分别降低了62.81%和71.39%。优化施用氮肥、增施有机肥、免耕秸秆覆盖能提高耕层土壤结构稳定性和有机质及其活性组分含量,并降低氮素流失风险,是洱海流域农田保护土壤和降低环境风险的重要措施。
In order to explore agronomic measures that can effectively improve the physical and chemical properties of soil and reduce the non-point source nitrogen pollution, a field experiment was conducted to study the effects of different agronomic practices on soil water-stable aggregates, organic matter fractions and soil nitrate nitrogen Effect of content. The results showed that no-tillage and organic manure application significantly increased the number of water-stable aggregates> 0.25 mm in topsoil, which reached 82.31% and 81.1%, respectively, compared with the conventional fertilization (79.00%) and blank treatment (76.53%) increased by 4.19% and 5.97%, respectively. Both of them could increase soil organic matter content in topsoil and significantly increase C / N ratio in topsoil. No-till coverage and organic doubling treatment of dissolved organic nitrogen ) Increased significantly by 28.20% and 28.68%, respectively. Compared with conventional fertilization, MBC increased by 74.77% and 68.54%, and microbial biomass nitrogen increased by 32.43% and 20.94%, respectively. And can significantly reduce nitrate residue in 0-20 cm soil, which is 62.81% and 71.39% lower than that of conventional fertilization. Optimizing the application of N fertilizer, increasing organic manure and no-tillage straw mulching can improve soil structural stability and the content of organic matter and its active components in plow layer and reduce the risk of nitrogen loss, which is an important measure to protect farmland and reduce environmental risk in Erhai Lake. .