Can No-till Sequester Carbon? Overcoming Conjecture with Data.

Soil could become an important sink for atmospheric carbon dioxide (CO₂) as global agricultural greenhouse gas emissions continue to grow, but this hypothesis needs supporting data.  Sequestering soil carbon (C) depends upon many factors including soil type, climate, crop, tillage, nitrogen fertilization, cropping history and rotation, as well as the degree of soil degradation.  Reduced tillage, especially no-till, can result in reduced CO₂ emissions and sequestering of C if sufficient biomass is produced and near continuous ground cover maintained. In this study we used micrometeorology to estimate the CO₂ flux between the surface and the atmosphere by calculating changes in CO₂ concentration and energy in and above the crop canopy or soil surface. The study used Bowen ratio energy balance (BREB) micrometeorology to quantify differences in CO₂ fluxes between contrasting tillage practices.  Flux calculations showed that no-till was a net sink for CO₂ while the tilled plot was a net source during 104 days of the 2015 growing season in north-central Ohio.   In contrast to the conclusions of most recent discussions on this topic, the present study indicates that tillage practices affect C sequestration in a way that is also commensurate with the need for crop productivity.