Effect of fertilizer management on the soil bacterial community in agroecosystems across the globe

Different types of fertilizer can significantly change soil fertility. The response of soil bacterial communities to different fertilization regimes has been studied widely, but the inconsistent results urged us to systematically study the effect of multiple environmental factors on bacterial diversity and composition under different fertilization regimes. Here, we conduct a meta-analysis of a global dataset from 105 publications to explore the effect of mineral nitrogen, straw, and manure addition on soil bacterial alpha-diversity (Shannon and Chao1 indices) and community composition. Mineral nitrogen and straw addition decreased the Shannon (mineral nitrogen: –4.48%; straw: –11.83%) and Chao1 (mineral nitrogen: –0.97%; straw: –11.57%) indices, while manure addition increased the Shannon (0.53%) and Chao1 (5.64%) indices. The three types of fertilizer all favored the growth of Proteobacteria, Actinobacteria, and Bacteroidetes and inhibited the growth of Acidobacteria and Nitrospirae. Manure addition had the greatest increase in the abundance of Proteobacteria, Bacteroidetes, and the least decrease in abundance of Nitrospirae. Manure addition increased soil organic carbon, total soil nitrogen, and soil microbial biomass carbon more than mineral nitrogen and straw addition. Mineral nitrogen and straw addition decreased soil pH, while manure addition increased soil pH. Soil environmental and climate factors significantly drove changes in bacterial alpha-diversity and community, particularly soil pH. In conclusion, manure addition is the preferred fertilization management for most agricultural ecosystems. These results can be used as a valuable reference for agricultural management strategies to maintain belowground bacterial diversity and composition in agroecosystems across the globe.