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在免耕制度中，进行作物覆盖，尤其采用豆科作物覆盖，可进一步改善土壤性质，增加表土有机质含量，改善土壤生物特性，为土壤微生物活动提供一个良好的生存环境。在施氮量为０和１６８ｋｇ／ｈｍ２、小区覆盖作物为毛野豌豆、冬小麦和未覆盖作物的条件下，研究了免耕玉米地的土壤生物特性。结果表明，毛野豌豆覆盖小区有机碳累积量最高，冬小麦覆盖小区和无作物覆盖小区在施氮后有机碳含量也有所增加。施氮与否对野豌豆覆盖区有机碳含量没有影响，但施氮后土壤ｐＨ值明显下降。野豌豆覆盖区对微生物数量有较大影响，其不施氮时细菌含量最高。不施氮的野豌豆覆盖区酸性磷酸酶、芳香基硫酸酯酶，β—糖苷酶和Ｌ—天门冬酰胺酶活性比其余处理方式都高。在小麦覆盖区和无作物覆盖区，施氮量为１６８ｋｇ／ｈｍ２时酶活性较高。土壤有机碳含量的增加，可增强土壤微生物活性，并为土壤中微生物分泌酶的固持，提供一个良好的环境。作物覆盖除了减少土壤流失外，还能显著地改善土壤生物特性，从而提高土壤肥力。
In the no-till system, the coverage of crops, especially the coverage of leguminous crops, can further improve the soil properties, increase the content of organic matter in the topsoil, improve the soil biological characteristics and provide a good living environment for soil microbial activities. The soil biological characteristics of no-tillage maize were studied under the conditions of 0 and 168 kg / hm2 of nitrogen application, plot coverage of field peas, winter wheat and uncovered crop. The results showed that the total organic carbon accumulation in the field was the highest, and the organic carbon content in winter wheat covered area and non-crop covered area also increased after nitrogen application. Nitrogen application had no effect on the organic carbon content in the pea covered area, however, the pH of the soil decreased significantly after nitrogen application. The area covered by the wild pea had a great influence on the number of microbes, and had the highest bacterial content when no nitrogen was applied. The activities of acid phosphatase, aryl sulfatase, β-glucosidase and L-asparaginase in the non-N application field were higher than those in other treatments. In the wheat-covered and non-crop-covered areas, the enzyme activity was higher when the nitrogen application rate was 168kg / hm2. The increase of soil organic carbon content can enhance the activity of soil microorganism and provide a good environment for the retention of enzyme secreted by soil microorganism. In addition to reducing soil erosion, crop cover can significantly improve soil biological properties and hence soil fertility.