Effects of Different Plastic Mulching Film on Soil Hydrothermal Status and Water Utilization by Spring Maize in Northwest China

The problem of residual film pollution in farmland caused by polyethylene mulching films is serious. The application effects of different mulching films combined with drip irrigation on maize planting in the Ili area, Xinjiang, China, were explored. In this study, four types of mulching films and non-mulching treatment were used to study the degradation properties of different plastic mulching and their effects on the dynamic changes of soil moisture, heat, and crop yields of maize under drip irrigation. The results showed that after 160 days of mulching film, only small cracks appeared in polyethylene mulching films. The degradation performance of white oxo-biodegradable film treatment was optimal than the black oxo-biodegradable film treatment. The quality loss rate of the two biodegradable films were 52.26 and 48.48%, respectively. Various mulching film treatments could increase soil moisture in the early stage of maize growth. At the 0–60 cm soil layer, the soil moisture under the white oxo-biodegradable mulching film and black oxo-biodegradable mulching film treatments were lower by 2.75 and 2.66% (p < 0.05) than the white polyethylene mulching film and black polyethylene mulching film treatments. The soil water consumption was highest in the non-mulching treatment, followed by biodegradable film, and the small least value was observed in the polyethylene film treatment. The average soil temperature at depth of 0–15 cm in white polyethylene mulching film, black polyethylene mulching film, white oxo-biodegradable mulching film, and black oxo-biodegradable mulching film treatments were 1.43, 1.16, 0.72 and 0.64°C higher than the non-mulching treatment, respectively. Mulching films treatment played a critical role in increasing production and improving water use efficiency. The black polyethylene mulching film treatment had the highest yield and the best water use efficiency. The black oxo-biodegradable mulching film treatment only reduces the yield by 0.33% compared to the black polyethylene mulching film treatment, and the water use efficiency was only reduced by 0.90% (p > 0.05). Comprehensive analysis showed that black oxo-biodegradable mulching film could be used as a substitute for polyethylene mulching film and can be applied to the production practice of drip irrigation maize in the Ili area.

Evaluation of Polyethylene Mulching and Sugarcane Cultivar on Energy Inputs and Greenhouse Gas Emissions for Ethanol Production in a Temperate Climate

Fossil energy inputs and greenhouse gas (GHG) emissions associated with the cultivation and transport of sugarcane (Saccharum officinarum) for bioethanol production in Tanegashima, Japan, were estimated by life cycle assessment (LCA). The aim was to understand the effects of combined systems of polyethylene mulching treatment (mulching at planting and every ratooning, MM; mulching only at planting, MU; and untreated, i.e., no mulching at all, UU) and cultivar (a cold-tolerant genotype, NiTn18, and a conventional variety, NiF8). The mulch treatments and cultivars were combined to create six cultivation systems that were used to conduct a comparative assessment of cradle-to-gate energy inputs and emissions for bioethanol production. The LCA results showed that the energy inputs and GHG emissions resulting from the MM/NiF8 system were 6.29 MJ L−1 and 0.500 kg CO2e L−1, which were 14% and 23% lower, respectively, than the corresponding values in the UU/NiF8 system. In contrast, the MU/NiF8 system increased the environmental loads slightly. The use of NiTn18 improved sugarcane performance and ethanol yields substantially as compared with NiF8, reducing energy inputs to 5.38, 5.24, and 5.55 MJ L−1 and GHG emissions to 0.473, 0.450, and 0.441 kg CO2e L−1 for the UU, MU, and MM treatments, respectively. The energy inputs and GHG emissions were similar among the systems, indicating that more flexible mulching treatments might be acceptable in the NiTn18 systems than in the NiF8 systems. The energy inputs and GHG emissions resulting from the UU/NiTn18 system were 14% and 5% lower, respectively, than those of the MM/NiF8 system, suggesting that it may be possible to overcome the handicap of sugarcane production in cold conditions by breeding cold-tolerant cultivars.