CATALYTIC POTENTIAL OF SOIL HYDROLASES IN NORTHEAST CHINA UNDER DIFFERENT SOIL MOISTURE CONDITIONS

An incubation test with black soil (Phaeozem), Albic soil (Albic Luvisols), brown soil (Cambisols), and cinnamon soil (Chromic Luvisol) from Northeast China was conducted under the conditions of 10%, 20% and30 % field capacity, and the kinetic parameters of soil urease, phosphatase, and arylsulphatase were determined, aimed to study the changes in the catalytic potential of these enzymes under different soil moisture conditions. All test enzymes exhibited typical Michaelis-Menten kinetic behaviors. The test enzymes exhibited the highest enzyme-substrate affinity (1/K-m) at 20% or 30% field capacity. With increasing soil moisture content, the V-max of test soil urease decreased, while that of soil phosphatase and arylsulphatase increased, with the maximum V-max/K-m of urease at 20% field capacity and that of phosphatases and arylsulphatase at 30% field capacity. To control soil moisture condition could be a feasible way in regulating the biochemical transformation processes of soil nutrients catalyzed by soil hydrolases.