长期施肥土壤中酶活性的剖面分布及其动力学特征研究

对连续25年的长期培肥试验地中土壤剖面酶活性的分布及土壤酶的催化反应特性进行了研究,结果发现,土壤脲酶、碱性磷酸酶和蔗糖酶活性在土壤剖面中的分布从表层到深层,酶活性依次减小;而多酚氧化酶呈波浪型分布。土壤中脲酶、碱性磷酸酶、蔗糖酶活性与相应土层的有机质含量呈极显著正相关;多酚氧化酶无此相关性。土壤脲酶和碱性磷酸酶活性均随时间的延长而逐渐趋于一个稳定值,且各个时段酶活性均为施肥处理高于不施肥处理,说明施肥能显著提高土壤酶活性。土壤脲酶和碱性磷酸酶酶促反应初速度(V0)均随温度和底物浓度的增加而增加,至一定温度和底物浓度时,V0不再增加;不同培肥措施下V0为:厩肥秸秆化肥对照。

Profile distribution of enzyme activity of long-term fertilization soil and its dynamic characteristics

Long-term balanced fertilization not only can increase the soil fertility and biologic property including enzyme in the surface soil remarkably,but also can improve soil profile property and reflect the function depth and the influence space scope of long-term fertilization effect.In this paper,we studied the relationship between enzyme activity of soil profile under different long term fertilization measures with organic matter and the influence rule of temperature and reactant concentration on the enzyme catalysis in the Loess Plateau,the results showed: from surface layer to in-depth layer,soil urease,alkaline phosphatase and inverstase activities reduced in turn,while the polyphenol oxidase activity appeared a 'wave' distribution in the profile.There was a significant positive correlation between soil organic matter and urease,alkaline phosphatase,inverstase at the corresponding soil layer,but it was not happened between organic matter and polyphenol oxidase.With the incubation time prolonging,activities of soil urease and alkaline phosphatase increased and reached to a constant at the end.Moreover,activities of soil urease and alkaline phosphatase were always higher in fertilization treatments than those in control treatmentindicating fertilizer application could improve soil enzymatic activities significantly.The V_0 value(the initial velocity of enzymatic reaction) of soil urease and alkaline phosphatase increased(along) with the rising of temperature and reactant concentrations,moreover,to a certain temperature and reactant concentration,V_0 no longer increased.The V_0 value of fertilizations showed the same order as following: BM>SW>CF>CK.