Research progresses of farmland microorganisms in fluvo-aquic soil of China Releasing of N,P and K of organic fertilizers and their effects on the contents of available Cu, Zn,Fe and Mn in soil Effect of combined application of microbial inoculum and fertilizer on white clover growth in reclaimed mine soil Effect of microbial organic fertilizer on seedling growth, yield and quality of flue-cured tobacco Effects of application of organic fertilizer under different planting densities on dry matter production and yield formation of summer maize Reduction of nitrogen fertilizer application under different crop rotation systems in paddy fields of Taihu Area