Environmental and Economic Impacts of Biodegradable Plastic Film Mulching on Rainfed Maize: Evaluations on Sustainability and Productivity

Fully biodegradable (Bio) plastic film is an alternative option to replace widely used polythene film in semiarid rainfed regions. However, its productivity and environmental friendliness remain unclear. Field observations were conducted using maize variety Pioneer 335 to evaluate the effects of Bio film mulching on soil hydrothermal status, carbon sequestration, and water productivity in a semiarid site of northwest China from 2016 to 2017. Six treatments were designed as (1) CK-1, ridge and furrow (RF) without mulching, (2) CK-2, conventional flat planting without mulching, (3) RFT, RF with transparent polyethylene film mulching, (4) RFB, RF with black polyethylene mulching, (5) RFS, RF with wheat straw mulching, and (6) RFBIO, RF with Bio film mulching. The results indicated the growth prophase of maize from sowing to silking stage received 160 mm of rainfall in cool and wet 2016, but decreased to 119.8 mm in warm and dry 2017. Bio film degradation was advanced at the mid stages of maize growth by 10 days in 2017 compared with 2016. Similarly to RFT, RFBIO significantly improved soil hydrothermal conditions compared with RFS, CK-1, and CK-2; however, its magnitude decreased at the maturity stage (P< 0.05). Both RFT and RFB had significantly higher grain yields, economic benefits and water use efficiencies than RFBIO and RFS did across two growing seasons (P< 0.05). RFBIO led to a steady improvement in soil organic carbon, light fraction organic carbon, and carbon to nitrogen ratio, which were better than those of RFT. Therefore, Bio film mulching might be environmentally friendly but not highly productive.