SOIL NUTRIENT CONTENTS AND ENZYMATIC CHARACTERISTICS AS AFFECTED BY 7-YEAR NO TILLAGE UNDER MAIZE CROPPING IN A MEADOW BROWN SOIL

No tillage is being populanzed for the rainfed maize production in Northeast China. In order to evalúate its effects on the nutrient contents and enzymatic charactenstics in upland soils of Northeast China, surface (0-20 cm) meadow brown soil samples were collected from the plots under no tillage and conventional tillage in a 7-year field experiment under maize cropping in Shenyang, with the soil pH, contents of total C, N, P and S and available N, activities of α- and (β-galactosidase, α- and (β-glucosidase, urease, protease, phosphomonoesterase, phosphodiesterase, and arylsulphatase, and kinetic parameters of (β-glucosidase, protease, phosphomonoesterase, phosphodiesterase, and arylsulphatase determined. Comparing with conventional tillage, no tillage increased the contents of soil total C, N, and S and available N, the activities of test enzymes, and the Vmax/Km of soil urease, protease, and phosphomonoesterase, but decreased the activity of soil α-galactosidase and the VmaxKm of soil (β-glucosidase significantly. All the results suggest that long term no tillage for the maize production on meadow brown soil of Northeast China could enhance soil nutrients storage and the turnover of soil N and P, but had definite negative effects on the transformation of soil C.