不同农艺措施对土壤有机质组分和氮素流失风险的影响

Effects of Different Agronomic Techniques on Soil Organic Matter Fractions and Risk of Nitrogen Leaching

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〉0．25mm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）含量较习惯施肥分另0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—20cm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，并降低氪素流失风险，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 seek the appropriate agronomic techniques, which could effectively improve physical and chemical characteristics of soil and reduce potential nitrogen leaching, a field experiment was carried out to study the effects of 5 tillage measures on water-stable aggregates, organic matter fractions and soil nitrate content in tilth soil of Edmi lake basin. The results showed that, the amount of 〉 0.25 nun water-sta- ble aggregates of the two treatments of no-tillage ＆ straw mulching and doubling cow manure combined nitrogen ~gulation were about 82.31 % and 81.1%, respectively, compared with conventional fertilization treatment （79.00 % ） and CK （76.53 % ） for increasing 4.19 % and 5.97 % averagely. The above two treatments could increase significantly the content of organic matter and the C/N ratio in tilth soil. The content of dissolved organic nitrogen of the above two treatments were higher than conventional fertilization treatment in tilth soil, about 28.20 % and 28.68 %, respectively. The soil microbial biomass carbon of the treatments in no-tillage ＆ straw mulching and doubling cow manure combined nitrogen regulation increased 74.77 % and 68.54 %, and soil microbial biomass nitrogen increased 32.43 % and 20.94 %. Compared with conventional fertilization treatment, 0 -20 cm soil nitrate residue of the above two treatments reduced to 62.81% and 71.39 % respectively. In eouclusiou, optimized application of fertilizer, applying organic manure combined with no-tillage and straw mulc- hing could improve tilth soil structure stability, and increase soil active organic matter content and reduce effectively the risk of nitrogen loss, which was a good choice for the tillage measure in Erhai Lake Basin.