Soil CO2 in organic and no-till agroecosystems

Increased carbon dioxide (CO2) concentrations in soil profiles could increase carbon sequestration via improved residence times of soil organic carbon (SOC), greater nutrient availability and plant growth, and via other pathways, but the effect of agricultural management techniques on soil CO2 is poorly understood. We used nondispersive infrared (NDIR) CO2 sensors to measure gas-phase CO2 concentrations in 1.50 m soil profiles in paired no-till (NT) and organic (ORG) agricultural systems in the Palouse region of eastern Washington State, USA, to investigate the effect of management on soil CO2. CO2 concentrations were significantly greater in ORG than in NT. The CO2 efflux into the atmosphere estimated using Fick's first law was generally greater in ORG due to both greater diffusivity and stronger concentration gradients observed in ORG. Results demonstrate that organic agriculture may facilitate greater soil CO2 concentrations and production rates. Further research is needed to quantify and understand the role of increased CO2 in soil carbon cycling in agroecosystems.