Characteristics of Soil Microbial Community under Different Cropping Systems in Flue-cured Tobacco Growing Areas of Shandong Province

The dynamics of soil microbial community structure in plough soils (0-25 cm) of four flue-cured tobacco cropping systems (tobacco, green manure-tobacco rotation, wheat-tobacco rotation and wheat intercropping) in tobacco growing area of Shandong province were studied by use of technique of phospholipid fatty acid (PLFA). The results showed that the treatment of green manure-tobacco rotation had the biggest mean total soil microbial biomass by PLFAs content as a whole, and the other three treatments were almost equal in the whole sampling period (one month before transplanting stage, rosette stage, bud stage, maturity stage). The order of microbial biomass of three major soil microbial communities was: bacteria> fungi> actinomycetes. The ratio of aerobes biomass to anaerobes biomass decreased in the whole sampling period. Furthermore, the soil microbial diversity indices of wheat-tobacco intercropping were biggest at each sampling period among four tobacco cropping systems.