Does High Soil Moisture in No-till Systems Increase CO2 Emissions and Reduce Carbon Sequestration?.

Soil respiration plays a crucial role in the global carbon cycle and the evolution of greenhouse gases into the atmosphere. The soil carbon storage in cropping systems is notably affected by intensive tillage practices that modify soil conditions. Soil physical properties control several processes including the storage and flow of water and gases from the soil, the oxidation of organic matter and microbial activity that contribute importantly to soil respiration. The objective of this study was to investigate the effect of soil moisture and temperature on soil respiration in long-term tillage experimental plots. We collected soil respiration data from a long-term experiment site at the Texas A&M University Research Farm in College Station, Texas. Soil carbon dioxide (CO₂) emissions were continuously measured in soybeans (Glycine max) using four automated chambers (Model LI-8100A, LI-COR Biosciences, Lincoln, NE, USA) and compared among tillage treatments implemented continuously over 33-years. Soil temperature and volumetric water content (VWC) were continuously monitored at 5cm, 10cm, 20cm and 30 cm during the growing season of soybeans using a soil water content reflectometer (CS655, Campbell Scientific). This research provides important insight of the effect of soil physical properties in sustainable production practices and in determining the potential of agroecosystems in sequestering or releasing carbon. More detailed results will be presented at the conference.