No-till farming and greenhouse gas fluxes: Insights from literature and experimental data

Authors: RUIS, SABRINA - UNIVERSITY OF NEBRASKA; BLACNO-CANQUI, HUMBERTO - UNIVERSITY OF NEBRASKA; JASA, PAUL - UNIVERSITY OF NEBRASKA; Jin, Virginia

Submitted to: Soil and Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/2/2022
Publication Date: 3/16/2022
Citation: Ruis, S.J., Blacno-Canqui, H., Jasa, P.J., Jin, V.L. 2022. No-till farming and greenhouse gas fluxes: Insights from literature and experimental data. Soil and Tillage Research. 220. Article 105359. https://doi.org/10.1016/j.still.2022.105359.
DOI: https://doi.org/10.1016/j.still.2022.105359

Interpretive Summary: Agricultural soils can store more carbon by decreasing the use of tillage and removing carbon dioxide (CO2) from the atmosphere where it would otherwise contribute to global warming. However, the extent to which agricultural soils themselves release CO2 and other greenhouse gases (GHGs) into the atmosphere in response to tillage is less clear, especially under long-term management. Here we measured soil GHG emissions for 26 months in a field experiment studying a gradient in tillage intensity (moldboard plow>chisel plow>double-disk>no-till) for the last 40 years. In this rainfed corn-soybean rotation in eastern Nebraska, we found that no-till practices, which had the least amount of soil disturbance, decreased soil CO2 emissions by 40-80% compared to other common tillage practices (double-disk, chisel plow, and moldboard plow). We also found that soil CO2 emissions increased with tillage intensity, with the highest emissions occurring in moldboard plowed soils. Tillage did not affect soil emissions of other GHGs (nitrous oxide and methane). Based on this study and an assessment of the global literature, using no-till management is expected to have the greatest long-term carbon benefits by both increasing soil carbon capture as well as decreasing soil CO2 emissions into the atmosphere.

Technical Abstract: Tillage intensity may differently impact gaseous losses of C and N to the atmosphere, but data from long-term experiments are relatively few. Yet, this information is needed to better understand C and N losses and gains in agricultural systems. The objective of this study was to determine how tillage intensity affects soil greenhouse gas (GHG) fluxes (CO2, N2O, and CH4) by comparing experimental data from moldboard plow (MP), chisel plow (CP), double disk (DD), and no-till (NT) soils after 38-40 yr of management in a rainfed cropping system that rotated corn (Zea mays L.) and soybean (Glycine max (L.) Merr). We also used a global literature review to evaluate the long-term impacts of tillage on soil GHG emissions. After 38-40 yr of management, CO2 fluxes decreased in this order: MP > CP = DD > NT, indicating that as tillage intensity decreased, CO2 fluxes decreased. Indeed, daily CO2 fluxes were typically lower under NT than under MP and CP. Similarly, the overall cumulative CO2 fluxes across 26-mo of measurement were 1.4 to 1.8 times lower with NT than MP, CP, and DD soils. Also, MP soils had 1.3 times higher CO2 fluxes than CP and DD soils. These results are similar to those from our global literature review of 60 studies on CO2 fluxes. The reduction in CO2 fluxes in NT was likely due to a combination of increased residue cover, reduced soil temperature (r = 0.71; n = 12; p < 0.001), and increased water content (r = -0.75; n = 12; p < 0.001). Daily N2O and CH4 fluxes were highly variable; and cumulative fluxes across the 26-mo study were unaffected by tillage, mirroring findings of our literature review of 37 papers on N2O fluxes and 24 on CH4 fluxes. Overall, based on the data from both the long-term experiment and literature review, NT appears to be the best option to reduce losses of CO2 followed by reduced till (DD), but N2O and CH4 fluxes do not generally differ with tillage intensity.