Soil CO2 in organic and no-till agroecosystems

Authors: LOCKHART, SUMMER - Washington State University; KELLER, KENT - Washington State University; EVANS, DAVID - Washington State University; CARPENTER-BOGGS, LYNNE - Washington State University; Huggins, David

Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2023
Publication Date: 2/28/2023
Citation: Lockhart, S., Keller, K., Evans, D., Carpenter-Boggs, L., Huggins, D.R. 2023. Soil CO2 in organic and no-till agroecosystems. Agriculture, Ecosystems and Environment. 349. Article 108442. https://doi.org/10.1016/j.agee.2023.108442.
DOI: https://doi.org/10.1016/j.agee.2023.108442

Interpretive Summary: Increasing soil Carbon storage can aid climate change mitigation. We found that soil CO2 (a major greenhouse gas) concentrations were greater in an organically managed farming system than in a paired no-till managed system down to 1.5m below the soil surface. We also discovered that CO2 left the soil of the organically managed system more effectively than in the no-till system. We concluded that soil CO2 production rates must have been greater in the organically managed system than in the no-till system and that the increased soil CO2 concentrations could increase carbon storage rates in the subsoil of organically managed systems. This research is important to researchers, farmers and agencies (NRCS) interested in climate-smart farming systems.

Technical Abstract: Increased carbon dioxide (CO2) concentrations in soil profiles could increase carbon sequestration via improved preservation of soil organic carbon (SOC), increased chemical weathering rates, increased photosynthetic rates, and other pathways, but the effect of different agricultural management techniques on subsoil CO2 is poorly understood. Soil profile CO2 concentration was measured in paired conventional no-till (CONV ) and organic (ORG) agricultural systems in the Palouse region of eastern Washington State, USA, to investigate the effects of agricultural management on soil CO2 concentrations. These concentrations were significantly greater in ORG than in CONV. Concentrations were greatest in both systems during the growing season (May-September). The rate at which CO2 diffused out of the soil profile towards the atmosphere was generally greater in ORG; the surface flux (soil respiration) estimated using Fick's first law was also greater in ORG, as expected considering the greater diffusivity and gradients observed in ORG. These results demonstrate that organic agriculture may drive increased subsoil CO2 concentration. Further research is needed to quantify and understand the effects of increased CO2 on subsoil carbon cycling in agroecosystems.