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

摘要

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.