Abstract: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.