| n order to study the effect and influence of human activities on spatial variability of soil organic matter and calcium carbonate in farmland,an experiment was made in the farmland of Duzhai Village,Yangling,Shaanxi,and meanwhile,the variation mechanism was analyzed.The results showed that the average soil organic matter contents in top soil and substratum soil were 20.64 g/kg and 10.81 g/kg,while the coefficients of variation were 0.087 and 0.013 respectively,belonging to a low level;the average soil organic matter content in subsurface was 16.96 g/kg belonging to a moderate level;a low level of variation coefficient of calcium carbonate appeared in all the soil layers.Through analyzing the contour map of soil spatial variability,the same changing law was found in soil organic matter and calcium carbonate content in the horizon direction,which showed that higher soil organic matter and calcium carbonate content appeared in the points closer to the village,forming a concentric circle. |