Quantifying the relative impact of climate smart agricultural practices on soil carbon uptake in the Central Mississippi River Basin Long-Term Agroecosystem Research (CMRB-LTAR) site

Authors: Schreiner-Mcgraw, Adam; Ransom, Curtis; Veum, Kristen; WOOD, JEFFREY - University Of Missouri; Sudduth, Kenneth - Ken; Abendroth, Lori

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/26/2023
Publication Date: 10/30/2023
Citation: Schreiner-Mcgraw, A.P., Ransom, C.J., Veum, K.S., Wood, J.D., Sudduth, K.A., Abendroth, L.J. 2023. Quantifying the relative impact of climate smart agricultural practices on soil carbon uptake in the Central Mississippi River Basin Long-Term Agroecosystem Research (CMRB-LTAR) site [abstract]. ASA-CSSA-SSSA Annual Meeting Abstracts. Paper 14837.

Interpretive Summary:

Technical Abstract: Climate smart agricultural practices have received considerable attention recently for their potential for climate change mitigation through sequestering atmospheric carbon. Despite the enthusiasm for climate smart practices, there is limited evidence they are more effective at removing carbon from the atmosphere and storing it in the soil than current practices. We hypothesized that a field with aspirational (ASP) practices (i.e., no-till corn-soybean-wheat-hay rotation with cover crops) would accumulate more soil organic carbon (SOC) versus a business-as-usual (BAU) field (i.e., conventional-tillage, corn-soybean-soybean rotation). We used deep soil cores (1 m) to assess changes in soil organic carbon ('SOC) between 2016 and 2022 for the two fields and compare with estimates based on eddy covariance calculation of 'SOC. We found that the ASP field had carbon uptake that was positive, and larger than the BAU field. Both the soil sample method ('SOCSS) and the eddy covariance method ('SOCEC) agreed on this point, but the magnitude of carbon uptake was much larger when estimated with soil samples ('SOCSS was 1.9 ± 1.7 % yr-1 and -0.7 ± 1.3 % yr-1 at ASP and BAU, respectively) than with eddy covariance ('SOCEC was 0.80 ± 0.09 % yr-1 and 0.12 ± 0.06 % yr-1 at ASP and BAU, respectively). Finally, we used the continuous measurements of carbon fluxes from the eddy covariance towers to evaluate which conservation practice (cover crops, no-till, or expanded crop rotation) led to the most carbon uptake. We found that cover crops, that were not harvested, were the primary cause for the difference in 'SOC between the ASP and BAU fields. The cover crops prevent carbon losses that otherwise occur when the field is fallow. Results from this study illustrate the value of conservation practices in a changing climate and the value of eddy covariance measurements for assessing climate smart practices.