Simultaneous measurement of bacterial abundance and composition in response to biochar in soybean field soil using 16S rRNA gene sequencing

Abstract Biochar is an important soil conditioner. However, we have limited understanding of biochar effects on the microbial community traits of the rhizosphere and bulk soil in the field. The aim of this study was to examine the impacts of biochar amendment on microbial abundance and community in the rhizosphere and bulk soils in soybean‐growing fields. We applied 16S ribosomal RNA (rRNA) gene sequencing with an internal standard gene to quantitatively investigate biochar‐mediated changes in microbial composition and abundance in rhizosphere and bulk soils. The results indicated that the absolute abundance of bacterial taxa with internal standard can be more informative in describing soil microbial population distribution. A linear discriminant analysis effect size differential analysis showed that the biochar amendment significantly altered the soil microbial abundance and community composition. The bacteria in the rhizosphere soil showed more clear responses to biochar addition than the bacteria in the bulk soil. These results highlight the enhanced effect by biochar on bacterial population distribution in the rhizosphere. 16S rRNA gene sequencing with internal standard gene represents an effective method that can substantially improve 16S‐seq based microbiome studies by determining the 16S rRNA gene abundance and bacterial community composition simultaneously.