Study on Soil Microflora in Different-aged Orange Plantations

[Objective] The research aimed to study the dynamic of soil microflora from different-aged orange plantations in Three Gorges Reservoir areas of Yichang.[Method] The soil samples were collected from three different-aged orange plantations,and conventional methods were used to determine soil pH,soil biomass carbon and nitrogen as well as soil primary nutrient content.The quantity of three soil microfloras were analyzed using the method of plate dilution.[Result] With the increasing of planting years,soil pH decreased,soil organic content and total nitrogen content first increased and then decreased,and the total microbial numbers decreased.Concentration of bacteria significantly reduced which were contrary for fungi.Little changes happened in concentration of actinomycetes.And the ratio of bacteria and fungi in soil(B/F) decreased.There was little change in soil microbial biomass carbon while significant reduction in soil microbial biomass nitrogen.[Conclusion] With the increasing of planting years,soil pH decreased,and the dynamic of soil microflora,soil microbial biomass carbon and nitrogen,the soil primary nutrient were affected,which further affected normal functions of soil.