Linking soil microbial community structure to potential carbon mineralization: A continental scale assessment of reduced tillage

Authors: REIKE, ELIZABETH - Soil Health Institute; CAPPELLAZZI, SHANNON - Soil Health Institute; COPE, MICHAEL - Soil Health Institute; LIPTZIN, DANIEL - Soil Health Institute; BEAN, GREGORY - Soil Health Institute; GREUB, KELSEY - Soil Health Institute; NORRIS, CHARLOTTE - Soil Health Institute; TRACY, PAUL - Soil Health Institute; ABERLE, EZRA - (NCE, CECR)networks Of Centres Of Exellence Of Canada, Centres Of Excellence For Commercilization A; Ashworth, Amanda; Baumhardt, Roland - Louis; Dell, Curtis; Derner, Justin; Ducey, Thomas; Fortuna, Ann Marie; Kautz, Mark; Kitchen, Newell; Moore, Philip; Osborne, Shannon; Owens, Phillip; Sainju, Upendra; Sherrod, Lucretia; Watts, Dexter

Submitted to: Soil Biology and Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2022
Publication Date: 3/11/2022
Citation: Reike, E., Cappellazzi, S.B., Cope, M., Liptzin, D., Bean, G.M., Greub, K.L., Norris, C.E., Tracy, P.W., Aberle, E., Ashworth, A.J., Baumhardt, R.L., Dell, C.J., Derner, J.D., Ducey, T.F., Fortuna, A., Kautz, M.A., Kitchen, N.R., Moore Jr., P.A., Osborne, S.L., Owens, P.R., Sainju, U.M., Sherrod, L.A., Watts, D.B., et al. 2022. Linking soil microbial community structure to potential carbon mineralization: A continental scale assessment of reduced tillage. Soil Biology and Biochemistry. 168. Article 108618. https://doi.org/10.1016/j.soilbio.2022.108618.
DOI: https://doi.org/10.1016/j.soilbio.2022.108618

Interpretive Summary: Over the past few decades numerous biologically based measurements have been designed to assess how agricultural management decisions affect soil functioning (e.g. cycle nutrients, decompose organic matter) and overall soil health. Current measurements used by the scientific community to evaluate soil heath include microbial biomass, and available carbon and nitrogen pools for microbial consumption. Increases in measurements are commonly interpreted under the assumption, “more is better”. However, greater values from these measurements are difficult to interpret because the measurements are not directly tied to increases in soil function, such as greater plant available nutrients or improved ecosystem benefits. Groups of organisms responsible for driving the metabolic processes that create agricultural or ecosystem benefits could be identified to better understand how measurements of microbial activity relates to soil health. Therefore, researchers set out to compare and recommend soil health indicators of carbon formation at 124 locations across Canada, Mexico, and the United States. The unique sampling design incorporated in this study elucidated soil bacterial communities that were enriched in soils under minimum tillage across soil types and climates. Results from this study indicate that type of cash-cropping system, intensity of physical disruption, and soil pH all influence the degree of bacterial sensitivity to tillage. These results can be used to provide expected impacts from soil management on a given soils function and resilience to environmental stress.

Technical Abstract: Potential carbon mineralization (Cmin) is a commonly used indicator of soil health, with greater Cmin values interpreted as healthier soil. While Cmin values are often greater in agricultural soils managed for minimal physical disturbance, the mechanisms driving increases in Cmin remain poorly understood. To better understand the drivers of Cmin values in soils managed for minimal physical disturbance, this study assessed changes in microbial community structure resulting from physical disturbance, as well as their influence on Cmin. Potential carbon mineralization, 16S rRNA sequences, and soil characterization data used in the study were collected as part of the North American Project to Evaluate Soil Health Measurements (NAPESHM). Results indicate type of cash-cropping system, intensity of physical disturbance, and soil pH all influence microbial sensitivity to physical disturbance. Furthermore, 28% amplicon sequence variants (ASVs), which were important in modeling Cmin, were enriched under soils managed with minimal physical disturbance. Sequences identified as important for modeling Cmin and enriched under minimal disturbance were linked to organisms which could produce extracellular polymeric substances and contained metabolic strategies suited for microcosms with finite nutrient concentrations. Enhancing interpretation of standardize Cmin measurements will provide stakeholders the context necessary to evaluate management impacts on soil function.