Legacy Effects of Cover Crop on Cash Crop Rhizosphere Microbiota in a No-Till Maize–Soybean Cropping System

Introducing cover crops is a conservation practice that diversifies cropping systems and counteracts the detrimental consequences of simplified cropping systems. However, the legacy effects of cover crops on cash crop rhizosphere microbiota are poorly understood. We investigated the response of cash crop rhizosphere microbiota following 5 years of cover crops (winter rye for maize and a mixture of winter rye, forage turnip, clover, Berseem, and Crimson for soybean) introduced into a long-term maize–soybean rotation. Five years of cover crop integration significantly increased the average soybean yields and marginally increased maize yields between 2018 and 2022. Cover crops had significant effects on soybean rhizosphere microbiota selecting bacterial genera within Actinobacteria and Thaumarchaeota phyla and some potentially pathogenic fungi species. There was no significant effect of cover crops on maize rhizosphere microbiota. Cash crop growth stage had consistent, significant effects on both soybean and maize rhizosphere microbiota and accounted for a higher percentage of variation in the rhizosphere microbiota compared with cover crops. Crop growth stage effects were notably strong at the flowering stage for soybean and the seedling stage for maize. The soybean rhizosphere was enriched with nitrogen-fixing bacteria in the flowering stage, whereas the maize rhizosphere recruited a high abundance of plant growth-promoting bacteria in the seedling stage. Cover crops did not significantly improve six selected soil health indicators, with the weak responses linked with cash crop identity. Cover crop legacies may promote beneficial changes in cash crop rhizosphere microbiota, but legacy assessments should account for cash crop identity and growth stage. [Figure: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.