Spatial heterogeneity of surface soil nutrients in small scale in the black soil region of Northeast China

In traditional crop production, farmers considered cultivated land as uniform growth conditions and take the same plan. In fact, There is a obvious spatial heterogeneity on farmland inside. The differences of micro topography and soil fertility affect the crop growth and yield. In our research, a experimental field is selected in a farm in Heilongjiang province, China. We collected 123 topsoil (0-20 cm) samples, and measured soil organic matter (SOM), ammonium nitrogen (NH3-N), soil available phosphorus (SAP) and soil available potassium (SAK). After descriptive statistics analysis of surface soil nutrients and semivariogram analysis. The fitting model and parameters of each surface soil nutrients were given. Spatial heterogeneity exists in surface soil nutrients. Especially, the topsoil (0-20 cm) soil organic matter present obvious regional regularity. The spatial distribution map of surface soil nutrients were drawn by the Kriging interpolation method. The research of spatial heterogeneity of surface soil nutrients in small scale provide the basis for the model of variable rate fertilization.