Changes in microorganisms and enzyme activities in soil under different grazing intensities in meadow steppe,Inner Mongolia

The accounts and biomasses(carbon and nitrogen) of the microorganisms and enzyme activities in soil under different grazing intensities in meadow steppe in Inner Mongolian Region were studied.The accounts showed in an order of bacteria actinomycetes fungi.The total account of the microorganisms in soil was greater for no-grazing treatment than for grazing treatments.The biomasses of the microorganisms in top 0-30 cm soil layer reached the highest value for the lightly grazing treatment,and was the lowest for the moderately grazing treatment.The urease and catalase activities in soil were higher for both lightly and moderately grazing treatments than for no-grazing and heavily grazing treatments.The accounts and biomasses of the microorganisms,and activities of protease declined with depth of the soil layer.There were positive correlations between the microorganism account and biomass and the enzyme activities.The total N content in the microorganisms was significantly and positively correlated with the bacterial account(P0.01),and with the quantities of actinomycetes and fungi(P 0.05).The total C content in the microorganisms was significantly and negatively correlated with the fungi quantity(P0.01),and with the actinomycetes quantity(P0.05).The account and the total N mass of the microorganisms were significantly and positively correlated with the activities of invertase,protease and catalase in soil.The total C mass in the microorganisms was negatively correlated with the activities of invertase,protease and catalase(P0.05).