Bt玉米秸秆分解对土壤酶活性和土壤肥力的影响

通过室内实验,研究了Bt玉米34B24和同源常规品种34B23、Bt玉米农大61和常规品种农大3138秸秆分解对土壤酶活性和土壤肥力的影响.结果表明,与34B23处理相比,34B24处理的土壤蛋白酶和酸性磷酸酶活性在观测期没有显著差异;7d时土壤脱氢酶活性显著提高,1、4、60和7d土壤蔗糖酶活性显著提高;30d时土壤脲酶活性显著提高,4d和7d时则土壤脲酶活性显著降低.2个Bt玉米处理和2个常规玉米处理的土壤酶活性也在某些时间有显著差异.秸秆分解90d后,34B24处理比34B23处理.显著降低了土壤速效磷和速效钾含量.以上差异与不同秸秆的化学构成有关,Bt基因的转化过程可能会影响受体作物秸秆的化学成分.应建立不同土壤类型土壤酶活性的标准分级体系,以便科学评价Bt玉米秸秆分解对土壤质量的影响.

Effects of Bt corn straw decomposition on soil enzyme activities and soil fertility

An incubation test with the straws of Bt corn 34B24 and its non transgenic isogenic line 34B23,Bt corn Nongda 61,and non transgenic Nongda 3138 was conducted to study the potential effects of Bt corn straw decomposition on soil enzyme activities and soil fertility.No significant difference in soil protease and acid phosphatase activities was found between treatments 34B24 and 34B23; but on day 75 of incubation,soil dehydrogenase activity was significantly higher in treatment 34B24 than in treatment 34B23.The same was true for soil invertase activity on days 15,45,60 and 75.Soil urease activity in treatment 34B24 was significantly increased on day 30,but decreased on days 45 and 75.A significant difference in several soil enzyme activities was also observed between the treatments of two Bt corn hybrids and their conventional cultivars at some sampling days.After incubation for 90 days,the contents of soil available P and K were significantly lower in treatment 34B24 than in treatment 34B23.The differences mentioned above resulted from the composition of test corn straws,which may be affected by the Bt gene transformation process.In order to accurately assess the effects of Bt corn straw decomposition on soil ecosystem,a standard classification system of soil enzyme activities should be established for different soil types from different regions.