Influence of terrain and grazing intensities on soil humus composition

In this experiment, the effects of terrain and grazing intensities on soil humic acid(HA), fulvic acid (FA) and the ratio of HA/FA in the light chestnut soil samples from Stipa breviflora desert steppe were analyzed and the relationship between soil humic acid, fulvic acid and soil organic carbon were discussed. The results showed that the contents of HA and FA in light chestnut soil were lower. Both HA and FA decreased with altitude rising and significantly decreased (P<0.05) with the grazing intensity increasement. With altitude rising, the ratio of HA/FA in soil decreased. The graze intensity had effects on the ratio of HA/FA in soil and the heavy graze had significant impacts (P<0.05) on the ratio of HA/FA in soil. With altitude rising, the correlation between each composition of soil humic and organic matter increased with altitude rising and decreased with the grazing intensity increasement. These results suggested that the studied region was suitable for lightly grazing and the stocking rate should be adjusted according to the different terrain.