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为探索秸秆深还田后土壤微生物碳氮和酶活性的动态规律,采用尼龙网袋的方法,研究秸秆还田到土壤不同深度(0 cm、0~15 cm、15~30 cm、30~45 cm)30天、60天、90天、120天后对土壤微生物碳氮和酶活性的影响。结果显示:秸秆还田120天,秸秆深埋分解率(70%~80%)远大于秸秆覆盖分解率(20%);比较各时期不同土层土壤微生物碳氮的变化,还田15~30 cm微生物碳含量最高,在各时期与其他处理达到显著差异,地表覆盖微生物氮含量最高,与其他处理达到显著差异;比较各时期不同土层土壤酶活性的变化,均为秸秆地表覆盖的土壤酶活性较高,土壤酶活性均随季节变化呈先升高后降低的趋势,秸秆还田90天后脲酶出现峰值,秸秆还田60天后蔗糖酶出现峰值。与对照相比,秸秆还田显著增加了土壤脲酶及蔗糖酶活性,且在还田15~30 cm,土壤脲酶及蔗糖酶活性的提高更加显著。相关性分析表明,秸秆还田深度与土壤微生物氮含量、土壤脲酶、蔗糖酶、土壤温度及土壤含水量有着显著地相关性。
In order to explore the dynamics of soil microbial biomass C and N and enzyme activities after returning straw to soil, nylon mesh bags were used to study the effects of straw returning to the soil at different depths (0 cm, 0 ~ 15 cm, 15 ~ 30 cm, 30 ~ 45 cm) on soil microbial biomass C and N and enzyme activities after 30 days, 60 days, 90 days and 120 days. The results showed that the straw decomposition rate (70% ~ 80%) was much larger than that of straw mulching (120%) after 120 days of straw returning. The changes of soil microbial carbon and nitrogen in different soil layers cm. The content of soil microbial biomass C was the highest, reaching significant differences with other treatments at different periods. The content of nitrogen in surface covered soil was the highest, which was significantly different from other treatments. Comparing the soil enzyme activities in different soil layers, The enzyme activity of soil increased firstly and then decreased with the season change. The urease peak appeared after 90 days of straw returning, and the peak of sucrase appeared after 60 days of straw returning. Compared with the control, straw returning significantly increased soil urease and invertase activities, and the soil urease and invertase activities increased more significantly after returning to field for 15-30 cm. Correlation analysis showed that straw depth and soil microbial nitrogen content, soil urease, invertase, soil temperature and soil moisture had a significant correlation.