Study on the mechanism of a new degradable and easily recyclable color matching mulch film to promote clean agricultural production process

The objective of this study was to investigate the ecological effects of a novel colored biodegradable mulching film (CM) on agricultural sustainability and environmental protection. Traditional polyethylene mulching films are difficult to degrade and recover, while biodegradable mulching films are costly, hindering their large-scale application. This research aimed to address these issues by comparing the degradation performance, mechanical properties, soil water-heat effects, and agricultural cleaning benefits (ACB) of CM, DM, and PM. METHOD: Field experiments were conducted in Shenyang and Jianping, Liaoning Province, China, using three types of mulching films: PM, DM, and CM. CM consisted of a central black polyethylene (PE) strip flanked by white biodegradable polybutylene adipate terephthalate (PBAT) strips. DM was made entirely of PBAT, while PM was conventional PE. The experiments were designed to assess the degradation rate, tensile strength, water-heat effects, crop yield, precipitation water use efficiency (PWUE), and ACB of the different mulching films. Soil temperature and moisture were measured using an ECH2O water temperature monitor. Degradation speed and mechanical strength were evaluated through visual grading and tensile tests, respectively. Field degradation rates were calculated based on mass loss, and the ACB was analyzed considering purchase, recovery costs, and recovery rates. RESULTS: Upon further examination of the degradation rates, it was observed that the white PBAT sections of CM (CM_W) degraded at a slower rate compared to DM, with a degradation rate of 77.48% after 120 days. This slight difference can be attributed to the color differentiation, as the white PBAT sections were designed to degrade more slowly to provide initial soil warming effects similar to traditional PE films. Despite this, the degradation rate of CM_W was still substantially higher than that of PM, which does not degrade and contributes to soil pollution. The black PE section of CM (CM_B) maintained a significant portion of its initial tensile strength, with 81.74% remaining after 105 days. This high tensile strength allowed for easy recovery of the CM_B sections, ensuring that they could be collected and disposed of properly, reducing soil pollution. The combination of the biodegradable white PBAT sections and the recoverable black PE sections makes CM a more environmentally friendly alternative to traditional PE and fully biodegradable films. In terms of soil temperature and moisture content, CM performed exceptionally well during the early stages of coverage. The highest temperature increase observed was 1.23℃, and the moisture content increase was 25.20% compared to DM. These improvements in soil conditions are crucial for crop growth and development, as they provide optimal conditions for seed germination, root growth, and nutrient uptake. The similar soil temperature and moisture retention of CM compared to PM further highlights its potential as a sustainable alternative to traditional mulching films. The economic analysis conducted in the study revealed that CM increased costs by 12 yuan per mu compared to PM. However, when compared to DM, CM saved 43.51 yuan per mu. These cost savings can be attributed to the reduced need for film recovery and disposal, as well as the increased crop yield and PWUE associated with CM. The recovery rate of CM_B was 82.31%, which is similar to PM and meets the requirement for over 85% residual film recovery. This high recovery rate ensures that the CM_B sections can be collected and disposed of properly, minimizing soil pollution. The agricultural cleaning benefits (ACB) of CM_B were not significantly different from those of PM. This finding suggests that CM can provide similar benefits in terms of soil health and crop productivity as traditional PE films, while also reducing environmental pollution. The combination of these factors makes CM a promising solution for sustainable agriculture and environmental protection. CONCLUSION: This study demonstrated that the novel colored biodegradable mulching film (CM) combines the advantages of traditional PE mulching films (PM) and biodegradable mulching films (DM). CM's black PE strip ensures high tensile strength for easy recovery, while the white PBAT strips degrade effectively, reducing soil pollution. CM achieves comparable crop yields and superior water use efficiency to PM while being more cost-effective and environmentally friendly than DM. Therefore, CM offers a promising solution for sustainable agricultural production and environmental protection.