Microorganisms play essential roles in agricultural systems, and their abundance, diversity and activity can be influenced by management practices. Crop rotational diversity is known to influence both soil microorganisms and crop productivity, yet the specific contributions of microorganisms to rotational benefits are unknown. To facilitate monitoring soil biological processes that support vigorous and high yielding crops, we studied maize (Zea mays L.) and soybean (Glycine max L.), and their associated microorganisms within a two-year maize-soybean rotation and within four-year crop rotations with varying crop sequences. We hypothesized that rhizosphere microbial communities are strong predictors of crop productivity contingent on rotational diversity and previous crop legacy. Sampling at seedling and flowering stages, we assessed rhizosphere bacterial and fungal communities, soil and plant tissue nutrients, aboveground biomass, and yield. Rhizosphere communities varied with rotational diversity and previous crop legacy. Concurrently, maize and soybean yield and biomass were approximately 15–25% larger in more diverse rotations and with different crop legacies, but there were no crop rotational effects on tissue or soil nutrients. Yield differences across rotational diversity or previous crop legacy were better predicted when microbial communities were considered. Fungal communities predicted lower maize seedlings biomass when following soybean, and lower soybean seedling biomass when following maize, independent of rotational diversity. Further, for maize, fungal communities predicted lower maize yield in the maize-soybean rotation, while in the four-year diverse rotations, bacterial communities predicted maize recovery from a soybean legacy by flowering. These results suggest that benefits of four-year rotations in maize and soybean production are driven by changes in plant pathogenic communities.

微生物在农业系统中起着至关重要的作用，其丰度，多样性和活动可能会受到管理实践的影响。已知农作物轮作多样性会影响土壤微生物和农作物生产力，但微生物对轮作效益的具体贡献尚不清楚。为了便于监测支持有力和高产作物的土壤生物学过程，我们研究了玉米（Zea mays L.）和大豆（Glycine max）。L.）及其相关微生物，在两年的玉米-大豆轮作中和四年的轮作中，具有不同的农作物序列。我们假设，根际微生物群落是作物生产力的有力预测指标，取决于轮作多样性和以前的作物遗产。在苗期和开花期取样，我们评估了根际细菌和真菌群落，土壤和植物组织养分，地上生物量以及产量。根际群落随着轮作的多样性和以前的农作物遗留而变化。同时，玉米和大豆的产量和生物量在更多样化的轮作中和具有不同的农作物遗留率的情况下大约增加15–25％，但没有农作物轮作对组织或土壤养分的影响。当考虑到微生物群落时，可以更好地预测轮作多样性或以前作物遗留的产量差异。真菌群落预测追随大豆时玉米幼苗生物量较低，追随玉米时大豆幼苗生物量较低，与轮作多样性无关。此外，对于玉米，真菌群落预测玉米-大豆轮作中玉米产量较低，而在四年的不同轮作中，细菌群落预测玉米通过开花从大豆遗留物中恢复。这些结果表明，玉米和大豆生产中每四年轮换的好处是由植物病原体群落的变化所驱动的。追随玉米时，较低的大豆幼苗生物量不受旋转多样性的影响。此外，对于玉米，真菌群落预测玉米-大豆轮作中玉米产量较低，而在四年的不同轮作中，细菌群落预测玉米通过开花从大豆遗留物中恢复。这些结果表明，玉米和大豆生产中每四年轮换的好处是由植物病原体群落的变化所驱动的。追随玉米时，较低的大豆幼苗生物量不受旋转多样性的影响。此外，对于玉米，真菌群落预测玉米-大豆轮作中玉米产量较低，而在四年的不同轮作中，细菌群落预测玉米通过开花从大豆遗留物中恢复。这些结果表明，玉米和大豆生产中每四年轮换的好处是由植物病原体群落的变化所驱动的。