Soil microbial community dynamics in plots managed with cover crops and no-till farming in the Lower Mississippi Alluvial Valley, USA

Authors: FIRTH, ALEXANDRA - Mississippi State University; Brooks, John; Locke, Martin; MORIN, DANA - Mississippi State University; BROWN, ASHLEY - Mississippi State University; BAKER, BETH - Mississippi State University

Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/2022
Publication Date: 12/6/2022
Citation: Firth, A.G., Brooks, J.P., Locke, M.A., Morin, D.J., Brown, A., Baker, B.H. 2022. Soil microbial community dynamics in plots managed with cover crops and no-till farming in the Lower Mississippi Alluvial Valley, USA. Journal of Applied Microbiology. 134(2); 1-13. https://doi.org/10.1093/jambio/lxac051.
DOI: https://doi.org/10.1093/jambio/lxac051

Interpretive Summary: The purpose of this study was to determine the change in bacterial community following a multi-year study on the effect of conservation practices into a continuous soybean system. The practices investigated included the use of cover crops and no till practices. Overall, the use of these practices influenced the bacterial community in the soil. Bacterial numbers increased with increasing moisture, particularly during the summer growing season, while reduced tillage was more effective at improving bacterial diversity. Interestingly, cover crop did not improve the bacterial diversity under no till under drought conditions when compared with reduced tillage, which would bring in more water to the system. Cover crops did affect the type of bacteria that were present in the systems, as would be expected. Overall, no till practices lowered the bacterial diversity of the system, while cover crop enacted a more temporary shift in bacterial communities. These practices can influence the bacterial presence and numbers in soil, but their positive or negative effect can be region dependent.

Technical Abstract: Aims: Assess bacterial community changes in soybean (Glycine max) crop fields following long-term CC and NT implementation under contrasting abiotic stressors (abundant water or drought). Method and Results: Soil bacterial community composition was obtained by amplifying, sequencing and analyzing the V4 region of the 16S rRNA gene. Generalized linear mixed models were used to assess the effects of tillage, CC and time on bacterial community response (community composition, phyla abundance shifts and bacteria diversity). The most abundant phyla present were Acidobacteria, Actinobacteria, Bacteroidetes, and Verrucomicrobia. Bacteria diversity increased in periods with abundant water. Reduced tillage increased overall bacterial diversity, but no-till with a cover crop was not significantly different than reduced till treatments under drought conditions. Cover crops shifted abundances of Firmicutes and Bacteroidetes depending on abiotic conditions. Conclusions: No-till practices lower diversity and influence long-term community changes while cover crops enact a seasonal response to environmental conditions. Significance and Impact of study: Given the environmental and agricultural productivity concerns of intensely managed soils, conservation practices that improve soil health and environmental integrity while mitigating the negative effects of crop production are critical. In the mid-South region of the United States, there is a lack of research on cover crop and no-till management’s impact on soil biology that is specific to the regional nuisances. The results show that no-till and cover crop management affect soil bacterial communities differently than found in other regions of the country and thus implementation must be uniquely approached.