Abstract:[Objective] The application of chemical fertilizers and straw returning are important agricultural strategies to improve the fertility of lime concretion black soil. However, there is little information about the impact of fertilization on microbial community in lime concretion black soil. The objective of this study was to investigate the effect of long-term application of chemical fertilizers and wheat straw returning on bacterial community in lime concretion black soil. [Methods] Quantitative PCR (qPCR) and 454 pyrosequencing-based analysis of the V4-V5 16S rRNA gene region were used to determine bacterial abundance, community structure and diversity in soils under different fertilization strategies. [Results] The most dominant bacterial phyla in lime concretion black soil were Actinobacteria, Proteobacteria, Acidobacteria, Chloroflexi and Bacteroidetes. Long-term application of chemical fertilizer greatly increased soil fertility, but resulted in significant bacterial community shift and diversity loss. Although wheat straw returning improved soil fertility, it could not mitigate the negative impact of chemical fertilizers on soil bacterial community. Statistical analysis revealed that changes in microbial community composition and diversity were strongly correlated with changes in pH induced by the fertilization regime. [Conclusion] Long-term application of chemical fertilizers and straw returning improved the fertility of lime concretion black soil, but soil acidification caused by fertilization had negative impact on soil bacterial community. Our results emphasized the importance of soil pH in addition to soil fertility for agricultural sustainability in lime concretion black soil region, and suggest that straw returning has little help for the stability of microbial community in lime concretion black soil, and comprehensive means must be taken to develop environmental friendly agriculture.
