P-341 - Changes to soil microbial assemblage and soil health indicators following biofumigation and application of composted manure

Soilborne diseases are a major challenge for U.S. potato production. While crop rotation, irrigation management, and resistant cultivars can help suppress soilborne diseases, soil fumigation is the most effective but costly management practice. Cultural practices, using organic amendments and biofumigant green manures in potato rotations, can suppress soilborne disease and promote beneficial microbial communities. We evaluated changes to microbial communities and soil health indicators following five soil treatments, non-treated, conventional fumigation, biofumigation and application of composted manure with and without biofumigation, in two- and three-year crop rotation experiments conducted over 4 years (2019-2022). We found the interaction between year and soil management practices explained 10% of the variation in bacterial communities (P_2-yr = 0.046; P<sub>3-yr < 0.001) and 9% to 11% in eukaryotic communities (P_{2- and 3-yr}  < 0.001). In 2022, the different soil management treatments explained 35% and 30% of the variation in bacterial and eukaryotic communities, respectively (P < 0.001). Application of composted manure significantly increased ACE Protein, CEC, and POXC indicators of soil health in 2022 compared to 2019 (P_{2- and 3-yr}  < 0.05). In 2022, soil health indicators correlated with bacterial and eukaryotic compositions (P_{2- and 3-yr}  < 0.05). Soil management practices influence soil microbial assembly and soil health indicators, but more research is needed to understand how management can be used to shape microbial communities in ways that enhance key soil functions.