Plastic mulching increased soil CO2 concentration and emissions from an oasis cotton field in Central Asia

Although previous researchers suggest that carbon dioxide (CO₂) emissions are influenced by plastic mulching, the effects of this method on soil CO₂ concentration and emissions remain uncertain. Soil CO₂ concentration and emissions from ridge and furrow soils under mulched and nonmulched treatments in 2014 and 2015 were measured. The soil CO₂ concentration was observed using modified diffusion equilibrium samplers, and the soil CO₂ emissions were measured using a closed‐chamber method. In the ridge soil, although the plastic mulching increased the CO₂ concentration by 49% (0–40 cm), no significant difference in CO₂ emissions was found between the mulched and nonmulched treatments. Accordingly, the relationship between soil CO₂ concentration and CO₂ emissions was affected by plastic mulching, with a lower slope of the linear equation found in the mulched treatment compared to the nonmulched treatment. In the furrow soil, the plastic mulching increased the CO₂ concentration and emissions by 15% and 21%, respectively. In conclusion, plastic mulching significantly increased the CO₂ concentration in both the ridge and furrow soils and increased the cumulative CO₂ emissions by 8%. The temperature sensitivity of the soil CO₂ concentration increased with soil depth, whereas the plastic mulching only influenced the temperature sensitivity of the soil CO₂ concentration in both the ridge and furrow soils at a depth of 40 cm. Our results suggest that the temperature sensitivity of the soil CO₂ concentration not only reflects the effects of temperature on CO₂ production but also indicates poor diffusion in the deep profile.