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.