Leveraging Microbe-Rhizosphere Interactions in Organic Farming Systems: A Route to Sustainable Soybean Production

Soybean (Glycine max L.) is a major legume crop of global agricultural significance, and its yield is heavily dependent on the rhizospheric microbes. Conventional farming systems can enhance yields in the short term but often at the expense of soil health and biodiversity. Organic farming systems, by contrast, avoid the use of synthetic inputs and depend on microbial processes to achieve yield. This review aggregates peer-reviewed literature on organic soybean farming systems, drawing from a body of work that has characterized the diversity, composition, and functions of rhizospheric microbes in these systems. Organic amendments such as compost, manure, and biochar enhance the abundance of microbial communities in the rhizosphere of organic soybean crops, buffer soil pH, and improve soil structure. Organic soils have greater microbial biomass and functional activity than conventional soils, with increased populations of bacteria such as Bradyrhizobium, arbuscular mycorrhizal fungi, Trichoderma, Streptomyces, and phosphate-solubilizing bacteria. The rhizospheric microbes are responsible for processes such as nitrogen fixation, phosphorus acquisition, organic matter decomposition, and induced systemic resistance (ISR). Measures of soil health, such as microbial biomass, enzyme activity, respiration rates, and soil organic matter (SOM) content, all demonstrate that organic farming systems have greater ecological value than conventional systems. Organic soybean production systems foster distinct rhizosphere microbial assemblages that confer measurable functional benefits to the agroecosystem. Future research is required in microbiome engineering, biostimulant design for specific applications, biomarkers for monitoring changes in soil microbiology, and precision organic farming systems. This review demonstrates that microbe-rhizosphere interactions are a key factor to consider in the development of sustainable agricultural practices for soybean production.