Microbial feedbacks on soil organic matter dynamics underlying the legacy effect of diversified cropping systems

Authors: MOOSHAMMER, MARIA - University Of California; GRANDY, STUART - University Of New Hampshire; CALDERON, FRANCISCO - Oregon State University; CULMAN, STEVE - The Ohio State University; DEEN, BILL - University Of Guelph; DRIJBER, RHAE - University Of Nebraska; DUNFIELD, KARI - University Of Guelph; Jin, Virginia; Lehman, R - Michael; Osborne, Shannon; Schmer, Marty; BOWLES, TIMOTHY - University Of California

Submitted to: Soil Biology and Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2022
Publication Date: 2/9/2022
Citation: Mooshammer, M., Grandy, S.A., Calderon, F., Culman, S., Deen, B., Drijber, R.A., Dunfield, K., Jin, V.L., Lehman, R.M., Osborne, S.L., Schmer, M.R., Bowles, T. 2022. Microbial feedbacks on soil organic matter dynamics underlying the legacy effect of diversified cropping systems . Soil Biology and Biochemistry. https://doi.org/10.1016/j.soilbio.2022.108584.
DOI: https://doi.org/10.1016/j.soilbio.2022.108584

Interpretive Summary: The use of crop rotations to increase yield and improve soil health has been used for centuries, but how these practices specifically affect soil organic matter (SOM) and soil microbial communities are still unclear. Here, we evaluated five long-term crop rotation experiments in the US and Canada to explore this question. We found that across these sites, crop rotations affected SOM chemistry in similar ways and that SOM sources were largely microbial in origin. Generally, soil resources were more available when crop rotation diversity increased. Our results highlight how the interaction between plants, soil and microbes contribute to improved soil health and crop productivity in more diverse crop rotations.

Technical Abstract: Crop rotations have well-known aboveground and belowground benefits. At regional to continental scales, the unifying mechanisms of how diversified rotations alter soil organic matter (SOM) dynamics have not been demonstrated. We assessed how increasing crop rotational diversity across a soil-climate gradient affected the integrated response of SOM chemistry, microbial community composition, and its enzymatic potential to degrade SOM. Agroecosystems with the same crop rotational diversity shared similarities in molecular SOM patterns with a strong microbial signature, pointing to common transformation processes. Differences in SOM chemistry between rotations were mainly characterized by shifts in microbial necromass markers and in lipids produced or transformed by microbes rather.