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黄土高原丘陵沟壑区陡坡天然草地，人工草地和农地土壤剖面的细菌、真菌、放线菌总数量以天然草地最多，人工草地最少。三大类群在农地上的数量分布有明显的层次差异，即随土层加深而减少。土壤蔗糖酶、脲酶、中性磷酸酶活性表现为：天然草地＞农地＞人工草地。地上部生物量以农地最高，天然草地最低，根系生物量则是农地最高，人工草地最低；微生物生物量与根系生物量一样为：农地＞天然草地＞人工草地。天然草地土壤剖面０～５０ｃｍ土层的微生物及其酶活性都较高，而农地只在０～１０ｃｍ的表土层有相对高的微生物数量和土壤酶活性。
The total number of bacteria, fungi and actinomycetes in the steep grassland, artificial grassland and farmland soil profile in the hilly and gully area of Loess Plateau is the highest in natural grassland and the least in artificial grassland. The distribution of the three major groups on agricultural land has obvious differences in levels, that is, it decreases with the deepening of soil layers. Soil invertase, urease and neutral phosphatase activities were as follows: natural grassland> agricultural land> artificial grassland. The aboveground biomass was the highest in farming land, the lowest in natural grassland, and the highest in root system was in farmland and the lowest in artificial grassland. Microbial biomass was the same as that in root biomass: farmland> natural grassland> artificial grassland. In the natural grassland soil profile, the soil microorganisms and their enzyme activities in 0 ~ 50cm soil layer were higher, while the soil layer only had the relatively high number of microorganisms and soil enzyme activity in the topsoil of 0 ~ 10cm.