[Effects of Long-term Fertilization Regimes on Microbial Biomass, Community Structure and Activity in a Paddy Soil]

Four paddy soils were collected in Ningxiang County, Hunan province. These used with different long-term fertilization regimes, including a control without fertilizer (CK), chemical fertilization with nitrogen, phosphate, and kalium (NPK), straw fertilization combined with NPK (ST), and manure fertilization combinedwith NPK (OM). Phospholipid fatty acid (PLFA) technology and Microresp^TM method were used to study the effect of long-term fertilization on soil microorganism abundance, community structure, and activity. Results showed that the abundance of bacteria, fungi, gram-negative (G^-) bacteria, and gram-positive (G⁺) bacteria in the soil from the OM treatment was generally higher than for the other treatments; these levels were lower in the ST and NPK treatments and lowest in the CK treatment. The principal components analysis (PCA) of PLFA showed that the community structure of microorganisms in NPK, ST, and OM treatments was altered in comparison with that in CK, especially in the case of the ST and OM treatments. MicroResp^TM results revealed that compared to the CK treatment (1.28 μg·h^-1), soil microorganisms in the OM treatment had the highest average utilization rate of multiple carbon sources (1.81 μg·h^-1), followed by ST (1.19 μg·h^-1), CK (1.28 μg·h^-1), and NPK (0.95 μg·h^-1). Furthermore, different long-term fertilization regimes resulted in distinct carbon source preferences for the soil microorganisms and revealed a significant alteration in the microbial community. Conclusively, long-term fertilizer with straw or manure changes the microbial community and is a benefit for improving the biomass and activity of microorganism in rice paddy soils.