Location: Integrated Cropping Systems ResearchTitle: Diverse rotations mitigate the mutual suppression of corn and soybeans through the rhizosphere
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/15/2020
Publication Date: 11/11/2020
Citation: Ewing, P.M., Benitez, M.S., Osborne, S.L., Lehman, R.M. 2020. Diverse rotations mitigate the mutual suppression of corn and soybeans through the rhizosphere [abstract]. Tri-Societies Annual Meeting, November 11, 2020. Virtual.
Technical Abstract: The corn-soybean rotation dominates the US Corn Belt, a top corn-producing region globally. Diversifying this rotation tends to increase both corn and soybean production, with an unknown mechanism. We tested whether crops were healthier in more diverse rotations, and whether this greater health was due to nutrient availability or to microbial activity. We studied five rotations from a long-term (16+ year) trial that varied in rotation length and the preceding crop. We sampled both corn and soybeans at the seedling and flowering stage. We measured rhizosphere bacterial and communities as well as tissue nutrients and biomass. In-season biomass predicted yields, which were greater in more diverse rotations. However, larger plants did not have higher nutrient concentrations, refuting a nutrient uptake mechanism. Bacterial and fungal communities did vary with rotation and, moreover, predicted biomass better than rotation. Lower seedling biomass was suppressed by fungal communities when the previous crop was corn or soybean, while at flowering, bacterial communities in longer rotations allowed a full recovery of crop biomass. These results support a microbial mechanism behind the production benefits of diverse rotations, and suggest the development of a microbial “syndrome” specific to corn-soybean rotations that reduce production potential.