Effects Of Fertilization On The Diversity Of Microorganisms And Microbial Phosphorus Transformation In Red Soils

Soil microorganisms play an important role in the transformation of soil organic matter and soil nutrients (such as N, P, S, ect.). Researches on the mechanisms of soil phosphorus transformation and the functional microorganisms which involving in the soil phosphorus transformation can provide a theory reference for the effective usage and management of phosphorus in red soils. Responses of culturable microbial diversity and the amount of microbial biomass P (MB-P) in upland and paddy soils and the diversity of soil microbial phytase gene in paddy soils with various fertilization practices (inorganic and organic fertilizer) were investigated using a series of long-term field trials in Hunan, China. Results indicated that combined application of rice straw and chemical fertilizers (NPK+Str) significantly increased the amount of culturable fungi and MB-P in treatment of NPK+Str by 68.4%～167.0% and 230.7%～344.5% respectively compared to CK,38.5%～46.1% and 161.1%～202.8% respectively compared to NPK in upland soils, whereas there's no significant dfference of culturable bacteria was observed among the treatment of CK,NPK and NPK+Str in upland soils, it suggested that fungi possibly played a key role in the phosphorus transformation in upland soils amended with rice straw. However, combined application of rice straw and chemical fertilizers with addition of astragalus (NPK+Str+GM) significantly increased the amount of culturable fungi, bacteria and MB-P significantly by 53.7%～112.3%,140.3%～374.1% and 33.9%～115.3% respectively compared to CK, 45.1%～144.6%.366.5%～410.9% and 21.4%～75.0% respectively compared to NPK in paddy soils, especially, the enhancement level of culturable bacteria was much higher than that of fungi, in compared with the treatment of CK and NPK. Consequently, this study demonstrated that bacteria and fungi likely play different roles of the information of microbial biomass P in upland and paddy soils, that is bacteria may contribute to the enhancement of MB-P which application of rice straw and organic green manure (astragalus) in paddy soils, however, fungi only play a major role in upland soil with the application of rice straw.Application of NPK fertilizer, rice straw and astragalus could increase the amount of Olsen-P by 2～3 times in upland and 4～6 times in paddy soils, meanwhile, the soil pH showed a significant decrease. The results suggested that the phosphorus transformation may be related to the decrease of soil pH. The long-term application of only NPK fertilizers had a potential to reduce the diversity of soil microbial phytase, however, application of NPK fertilizer amend with rice straw and astragalus could avoid the soil degradation to some extend.