Effect of microrelief on the spatial variability of carbon content of a Podzoluvisol in a long term field trial

The relationship between microrelief and spatial distribution and variability of the soil C-t-content was investigated in a rang term field experiment with different fertilizer and herbicide treatments near Moscow. Only 20% of the C-t-variability were related to agricultural factors. In order to analyse the influence of the microrelief on soil C-t-content the relief was formalized. This formalization included the calculation of the local inclination,local water gathering area and local relative intensity of the temporary water streams, while distinguishing between convex and Concave relief forms. Relief forms of different order were identified by kriging with different distances between the black centers. The parameters of the formalized relief were compared with the C-t-content of the soil by means of semivariograms and correlations. Through combination of relief parameters, it was possible to divide the field into different elements characterized by different correlations and effect types. The water gathering relief forms with maximal values of the relative intensity of the water streams and the arched forms with increasing intensity reduced soil C-t-content. C-t-accumulation occurred at transit positions between the convex and concave relief forms with medium intensity.