PS 20-14 - Soil Microbiome Management for Enhancing Soil Fertility and Crop Productivity

Abstract: Conservative agricultural management practices, such as no-tillage, cover cropping, and inherent soil properties management, have long-term ecological benefits. However, farmers may be hesitant to adopt these practices due to a lack of experience, initial expense, and concerns about low crop productivity. To overcome this barrier, managing the soil microbiome can be a practical approach to attain high productivity at a low cost, especially in semi-arid regions. In this study, we investigated the potential of conservation agriculture by evaluating the bacterial diversity and rhizobial diversity of soil samples collected from long-term experimental cotton fields managed using conventional tillage with winter fallow (CT) and no-tillage with mixed cover crop (M-NT) systems on the Texas High Plain (THP). Our research objectives were: (1) to evaluate the bacterial and indigenous rhizobial diversity of the two soil management practices during fall and summer, (2) to assess the potential for managing rhizobial diversity to enhance the benefits of legumes within a mixed species cover crop scenario when transitioning from conventional tilled to no-tilled management and in future years, and (3) to determine the critical bacterial taxa that could differentiate CT and M-NT using supervised machine learning. We conducted next-generation amplicon sequencing targeting the rpoB gene with collected soil samples from different soil managements and seasons. Our findings suggest that while CT had significantly greater bacterial diversity and species richness than M-NT management, rhizobial diversity and species richness were higher in M-NT than in CT management. Both bacterial and rhizobial diversity and richness were greater in summer than in fall. The abundance of the order Rhizobiales was consistently high in M-NT than in CT fields in both seasons. Soil management altered the dominant rhizobial genus associated with cotton production systems, where Rhizobium and Pararhizobium dominated M-NT management, while Bradyrhizobium and Sinorhizobium were dominant under CT management. These outcomes suggest that incorporating legumes into a cover crop in this semi-arid cotton-growing region can initiate beneficial changes to the dynamics of the indigenous rhizobial assemblage.