玉米秸秆还田对土壤酶活性的影响
Effects of maize straw returning on soil enzyme activity

【目的】研究不同玉米秸秆还田量对土壤酶活性的影响，为秸秆还田提供一定的理论依据。【方法】以采自陕西杨凌农田的土娄土为供试土样，采用室内模拟恒温培养方法，研究玉米秸秆不同还田量（0，6，12，18，24 g/kg）处理下，影响碳、氮循环及微生物活性的主要土壤酶类（蔗糖酶、纤维素酶、脲酶、脱氢酶和荧光素二乙酸酯（FDA）水解酶）活性在不同培养时间（1，4，7，15，30，60 d）的变化规律，并引入“倍增剂量”的概念评价酶活性的变化幅度。【结果】玉米秸秆还田后5种土壤酶活性均增强，随着培养时间延长，土壤蔗糖酶和纤维素酶活性总体呈减少趋势；脲酶和FDA水解酶酶活性总体呈先增后减的趋势；土壤脱氢酶活性培养初期较低，随着培养时间延长维持在一个较高水平，至培养60 d时明显降低。拟合结果显示，5种土壤酶活性与玉米秸秆还田量间均呈极显著正相关，不同酶活性的倍增剂量在不同培养时间下的变化有所差异。5种土壤酶中，以土壤FDA水解酶活性对玉米秸秆腐解过程最为敏感；当玉米秸秆还田量为10 g/kg时土壤总体酶活性较高。同时，玉米秸秆还田后，5种土壤酶活性间呈极显著正相关，表明其变化是密切相关的。【结论】玉米秸秆还田对5种土壤酶活性均具有较强的促进作用，从土壤总体酶活性角度得到当地玉米秸秆还田的最佳用量是10 g/kg。
【Objective】Influences of maize straw decomposition on soil enzymes were studied to provide reference for maize straw returning.【Method】Using laboratory simulation method,effects of maize straw returning at different amounts （0,6,12,18,and 24 g/kg） on soil enzymes,including soil invertase,cellulose,urease,dehydrogenase and fluorescein diacetate hydrolase influencing soil cycling carbon,nitrogen cycling and microbial activities after cultivating 1,4,7,15,30,60 day were studied,Also,dose of double enzyme activity(DDEA) were calculated to evaluate the increase of enzyme activity.【Result】Activities of five soil enzymes increased with maize straw returning.Soil invertase and soil cellulose activities decreased as the straw decomposition process prolonged.Soil urease and FDA hydrolase activities increased at the beginning of straw decomposition and then decreased during cultivation.Soil dehydrogenase activities were low in the initial cultivation,then reached a high level during the cultivation,and significantly reduced in the 60th day.There were significant positive correlations between soil enzyme activities and the amount of straw returning.Meanwhile,DDEA of different soil enzyme changed during the cultivation.During straw decomposition process,FDA hydrolase was the most sensitive enzyme.10 g/kg was the suggested straw returning amount with the highest total enzyme index.Activities of the five soil enzymes showed significant positive correlation,indicating that their responses were closely related.【Conclusion】Maize straw returning increased soil enzyme activities,and 10 g/kg was the optimized amount in the area