Behavior of carbon dioxide in soils affected by tillage systems

Agricultural management plays an important role in the storage of carbon in soils. The behavior of soil CO₂ in an Andisol in two different tillage systems (no tillage and tillage) was studied. Soil-column incubation experiments were performed for a period of 150 days to conduct this study. Soil CO₂ flux, under no-tillage and tillage treatments, was observed to be 0.557 and 0.616 gCO₂-C m^?2 d^?1, respectively. The cumulative CO₂ flux under tillage treatment was observed to be higher than that under no-tillage treatment, but no distinct difference in the soil carbon stock was observed between both treatments. The soil CO₂ concentration under no-tillage treatment was clearly much higher than that under tillage treatment, except at a depth of 2.5 cm. Tillage decreased soil dry bulk density and enhanced soil air-filled porosity. Soil gas diffusivity, which depends on air-filled porosity, was increased by tillage at a depth of 0–15 cm, which contributed to their lower soil CO₂ concentration. CO₂ flux through the soil profile, calculated from the CO₂ concentration, decreased with depth. Compared to the deep soils, the surface soil (0–5 cm) showed greater variation in CO₂ flux. The CO₂ production at depths of 0–10 cm accounted for 62.2 and 51.7 % of the whole CO₂ production of the 0–30-cm soil profile for no-tillage and tillage treatments. CO₂ production was higher for soil under no tillage at depths of 0–10 cm, but contrary results were observed for soil at depths of 10–30 cm.