Exploring the diversity and composition of soil microbial communities in different soybean-maize management systems.

Soybean-maize are cultivated in different management systems, such as no-tillage and pastures, which presents potential to add organic residues, and it can potentially impacts the soil microbial community present in these systems. Thus, this study aimed to examine the effects of different soybean-maize management practices on the diversity and composition of soil microbial communities. Specifically, 16 S rRNA amplicon sequencing was used to investigate whether the use of pasture species in a fallowing system influences microbial communities in a soybean-maize rotation system, as compared to conventional tillage and no-tillage systems. The results indicate that the inclusion of the pasture species Urochloa brizantha in soybean-maize management systems leads to distinct responses within the soil microbial community. It was found that different soybean-maize management systems, particularly those with U. brizantha, affected the microbial community, likely due to the management applied to this pasture species. The system with 3 years of fallowing before soybean-maize showed the lowest microbial richness (∼2000 operational taxonomic units) and diversity index (∼6.0). Proteobacteria (∼30%), Acidobacteria (∼15%), and Verrucomicrobia (∼10%) were found to be the most abundant phyla in the soil under tropical native vegetation, while soils under cropland had an increased abundance of Firmicutes (∼30% to ∼50%) and Actinobacteria (∼30% to ∼35%). To summarize, this study identified the impacts of various soybean-maize management practices on the soil microbial community and emphasized the advantages of adding U. brizantha as a fallow species.