Microbial biomass and community composition in a Luvisol soil as influenced by long-term land use and fertilization

Soil microbes play important roles in decomposition of organic matter, nutrient cycling, and plant nutrient availability, yet whether their biomass and community structure could reflect soil quality and what main factors influencing them remain unclear. We investigated the effects of long-term (19years) land use and fertilization on soil microbial community structures in a Luvisol soil. The experiment involved seven treatments: four cropping treatments containing no fertilizer (CK), recycled manure (RM), fertilizers nitrogen (N)+phosphorus (P)+potassium (K) (NPK), NPK+RM, and three no-crop treatments including bare land, mowed fallow, and non-mowed fallow. The biomass and community composition of microbes in this soil were analyzed by phospholipid fatty acid (PLFA) and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) approaches. Our results showed that the microbial PLFA concentrations were significantly affected by different land use types, and decreased in the order of non-mowed fallow>mowed fallow>four cropping treatments>bare land. Although no significant difference was observed in the microbial PLFA concentrations among four cropping treatments, we found that manure application promoted microbial growth, while mineral fertilization suppressed it. PCR-DGGE profiles revealed that fungal community structures were more significantly alerted by long-term land use and fertilization than bacterial community. Overall, we concluded that different land use types exerted greater impacts on soil microbial biomass and community structures than fertilization regimes in the Luvisol soil. Moreover, the changes of microbial biomass and community structures mainly resulted from differences in soil total C and N contents. ► We report the effect of long-term land uses and fertilizations on microbes. ► Tillage practice has greater influence than fertilization on microbial community. ► Fungal community was more significantly alerted to long-term fertilizations.