Characteristics of change of humic substance in soil in degraded grass lands

摘要

The test of soil in and outside sheep-pasturing herb pens on the undegraded and degraded grass lands showed that the amount of biomass at the test sites ranges in such on order: in herb pen＞outside herb pen＞in degraded herb pen＞outside degraded herb pen. Amounts of nitrogen, humic substance, humic acid, and fulvic acid in soil increased with increasing biomass and follow also the above-mentioned order. of them humic acid its functional group in herb pen increased significantly and hence the herb pen was better in quality.