Plastic Film Mulching Increases Soil Respiration in Ridge-furrow Maize Management

The cultivation practice of ridge-furrow with full plastic film mulching has been significantly promoted for crop production and is now used extensively in northwest China. There is still a dearth of information on the change in carbon dioxide (CO2) emission under plastic film mulching. A study was implemented to assess how plastic film mulching altered the soil profile CO2 concentration and fluxes within a whole growing season; moreover, through the total carbon budget, to evaluate the potential risk of this cultivation system. A full plastic film-mulched ridge-furrow (PM) treatment and a conventional ridge-furrow treatment without mulching (CK) were studied. The plastic film had a significant blocking effect on CO2 release, and the soil profile CO2 concentration in PM was twice that of CK. The CO2 diffusion coefficient for PM was only 48% of the CK value. The soil profile CO2 concentration increased with soil depth and the concentration in furrows was lower than in ridges at the surface (0–10 cm) but higher in the deeper soil (10–30 cm). More soil organic carbon was lost in PM, and total emitted CO2 in PM was 22% higher than for CK. Meanwhile, the total biomass in PM was 39% higher than that in CK. This study demonstrated that full plastic film mulching was an effective management to increase crop production. However, it could have a negative effect on soil carbon storage and controlling greenhouse gas emissions.