To evaluate the impacts of land degradation on soil microbial attributes in sandy cropland,we examined soil microbial biomass and microbiological activities in a typical agro-pastoral transitional zone in Naiman County of northern China.Lightly degraded cropland(LDC),moderately degraded cropland(MDC)and heavily degraded cropland(HDC))were chosen according to the magnitude of sand invasion.Both microbial biomass and microbiological activities(quantified as microbial abundance and enzyme activities)decreased significantly as degradation level increased from LDC to MDC and HDC.In addition,correlations between soil microbial biomass carbon and microbiological activities were significant and positive.Further analysis of this relationship identified three key microbiological factors influencing the level of soil microbial biomass carbon.Activity of the enzyme Cellobiohydrolase,and the abundance of Azotobacter and Actinomycete,were significantly related to soil microbial biomass carbon(stepwise regression: Microbial biomass carbon =-147.944 + 5.451*Cellobiohydrolase + 2.090*Azotobacter-0.053*Actinomycete(R2=0.971,F=122.941,P＜0.001).Thus in Horqin sandy land,cropland degradation reduces not only the productivity and yield,but also the soil microbial attributes.
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