不同种植制度土壤氧化还原酶活性和动力学特征

Soil oxidoreductase activity and its kinetic characteristics under different cropping system

土壤质量与土壤的生物学性质密切相关,种植制度对土壤生物学特性的影响研究对土壤质量管理具有重要的意义。以黑龙江853农场不同种植制度土壤为研究对象,探讨种植制度对土壤理化性质,过氧化氢酶、脱氢酶活性和动力学特征的影响。主要研究结果:农作物轮作有利于提高土壤全碳含量,而大豆连作和玉米-大豆轮作使土壤有效氮和全氮含量提高,大豆连作土壤pH显著低于其它作物连作及轮作处理,全磷含量显著高于其它处理;2种轮作体系均提高土壤过氧化氢酶活性和催化能力,且催化能力的提高源于酶的Km降低(即酶-底物亲合力提高);玉米-小麦-大豆轮作提高土壤脱氢酶活性及催化能力,其催化能力的提高由2个动力学参数的变化共同决定,禾本科作物连作土壤动力学参数与豆科作物种植(大豆连作及与禾本科轮作)具有显著差异。本文的研究表明,合理的轮作方式是提高土壤生物学活性的有效手段。

Soil oxidoreductase is a group of soil enzymes playing important roles in soil matter cycling and self-purification. In order to investigate its activity and kinetic characteristics under effects of different cropping system, albic soil samples under continuous cropping of maize, wheat, and soybean, and rotation of maize-soybean, and maize-wheat-soybean were collected from a state farm in northeast Heilongjiang Province, with the catalase and dehydrogenase activities and kinetic parameters as well as the chemical properties determined. Comparing with continuous cropping, rotation increased the activity and catalytic capability of soil catalase. Maize-wheat-soybean rotation also increased the activity and catalytic capability of soil dehydrogenase. Significant differences were observed in the kinetic parameters of test enzymes between continuous cropping of gramineous crops and continuous cropping of or rotation with leguminous crop. Rotation benefited the increase of soil total C, and continuous cropping of soybean and rotation of maize-soybean increased the contents of soil total N and available N. Under continuous cropping of soybean, soil pH was significantly lower and soil total P content was significantly higher, comparing with those under other cropping systems. All the results indicated that rational rotation mode was advantageous to the enhancement of soil biological activity and soil fertility.