Effects of cotton continuous cropping on the amount of soil microbes and enzyme activities in Xinjiang

The amount of rhizosphere soil microbes and enzyme activity and soil physical and chemical properties in cotton continuous cropping in Xinjiang were studied.The results showed:(1) With increasing continuous cropping years,bacteria were first increased and then decreased,while the amount of Fungi was decreased.The number of actinomycete was not obviously affected,and cotton soils converted from bacteria type to fungi type after continuous cropping.(2) Activities of urease and protease were also first increased and then decreased.(3) The correlation analysis among the amount of soil microbes,enzyme activities and soil physical and chemical properties showed:Urease and protease were positively correlated with bacteria.The correlation between urease and bacteria reached extremely significant level(ρ0.01).Protease had also reached significant level(ρ0.05).Enzyme activity had no significant correlation with the amount of actinomycete and fungi.Bacteria had significantly positive correlation with OM,total N and avail.N and had negative correlation with total salt.