Understanding the Effect of Tillage and Environmental Factors on the Diurnal Patterns of Soil CO2 Flux.

The release of carbon dioxide (CO₂) into the atmosphere, known as soil respiration, is highly sensitive to changes in environmental conditions, land use, management, and vegetation characteristics. Determining the variables that drives soil CO₂ flux can help to assess the impacts of soil managements and to evaluate the land-use adaptation to future climate change. In this study, we are currently investigating the factors affecting the magnitude and pattern of diurnal and seasonal changes in soil CO₂ flux at an agroecological long-term experiment site at the Texas A&M University Research Farm. Soil CO₂ flux is being collected continuously using automated closed-chamber systems in various tillage systems. Soil moisture and temperature at 5, 10, 20 and 30 cm depth are being monitored and related to soil respiration. Preliminary data collected indicated that soil respiration was highly affected by soil temperature and moisture, and crop development. The diurnal soil CO₂ flux peaked around 3 PM and followed the same pattern independent of the tillage practice. We found that the magnitude of the soil CO₂ flux was significantly lower under no-till (2.7 µmol m^-2 s^-1) compared to conventional tillage (4.2 µmol m^-2 s^-1). The results from this project are significant in determining carbon dioxide emissions under various environmental conditions and time-scales that can improve estimating the carbon fluxes from agricultural systems. Further results will be presented at the conference