China has nearly 300 million acres of plastic film-covered planting area, making plastic film planting an essential measure to ensure national food security and achieve the goal of "Chinese people holding their own rice bowls." Provinces like Xinjiang, Gansu, and Inner Mongolia have found it difficult to return to the era without plastic films due to the widespread use of ultra-thin films and improper reuse, leading to increasingly severe residual pollution on agricultural land. This has become a significant factor hindering sustainable agricultural development and requires urgent governance.
The Chinese government attaches great importance to the governance of residual film pollution in farmland. Starting from 2022, the Ministry of Finance, in collaboration with the Ministry of Agriculture and Rural Affairs, will organize pilot projects for the scientific use and recycling of plastic films, focusing on promoting thicker high-strength plastic films and fully biodegradable plastic films to enhance the level of mechanized recovery and post-treatment of plastic films. The pilot areas are distributed in multiple counties across nine provinces and regions nationwide.
Taking Xinjiang as an example, the focus of residual film pollution control is on cotton fields. From 2018 to 2022, the cotton planting area in Xinjiang has remained around 38 million acres, with a coverage rate of over 90% and an average of 5.5-6 kilograms of plastic film used per acre. The long-term cultivation of cotton has led to severe residual film pollution in agricultural fields. Xinjiang has basically achieved full mechanization in cotton planting, laying the foundation for full mechanized recovery of residual films in the current season.
The governance of residual film pollution in farmland is a comprehensive project involving legal regulations, subsidy policies, reduction in plastic film usage, application of biodegradable plastic films, mechanized recovery of thicker high-strength plastic films, and the resource utilization of recovered films. In the sector of mechanized recovery of thicker high-strength plastic films, the key lies in developing advanced and applicable film recovery machinery.
Achieving mechanized recovery of residual films in farmland is an inevitable step, with human-machine collaboration or manual picking being temporary measures. Research efforts should be intensified in the mechanized recovery technologies and equipment for crops like corn, potatoes, and peanuts to achieve breakthroughs promptly. Improvements in cotton field residual film recovery technologies and equipment should focus on enhancing the durability and reliability of key components, strengthening research on manufacturing processes, and setting standards to build a solid foundation. The technology and equipment for recovering residual films in the tillage layer are notably lacking and require further research to meet the goal of addressing residual film pollution in farmland comprehensively.
For technologies and equipment used in the recovery of residual films with high yield and low impurity rates, the requirements include high recovery rates, low impurity rates, high reliability of recovery machinery, improved operational efficiency, and achieving resource utilization of recovered films. It is essential to increase the volume of recovered films to facilitate the scaled operation of related enterprises for resource utilization.
The reuse of residual films aims to find outlets for the films, avoiding long-term land occupation and secondary pollution. For instance, residual films can be processed into molded products like PE pipes, well rings, well covers, drip irrigation belts, or mixed with wood powder, straw, and other waste plant fibers to produce boards or profiles. Chemical methods can also be employed to recycle and refine residual films into oil.
The national attention to the resource utilization of residual films is significant, with support from the Ministry of Agriculture and Rural Affairs. However, there are few enterprises engaged in comprehensive post-treatment and utilization of recovered films in the long run due to challenges such as insufficient volume of recovered films, inadequate raw material supply to meet processing requirements, lack of production continuity, and inevitable poor profitability.
Currently, there is a lack of advanced and applicable technologies and equipment for comprehensive post-treatment and utilization of mechanically recovered residual films. In regions like Gansu, Inner Mongolia, and Xinjiang, the post-treatment and utilization of residual films are mainly limited to water washing and granulation, which consume a lot of energy and have low efficiency. The raw materials are mostly plastic films picked manually, with relatively high impurity rates in mechanically recovered films in Xinjiang, requiring manual assistance in clearing soil impurities to achieve comprehensive post-treatment and utilization, leading to increased costs and limited economic benefits.
One prominent issue is the large amount of mixed waste left after initial cleaning of mechanically recovered residual films transported back to factories, posing a challenge in handling and disposal, which is difficult for any individual farmer to accept. Mobile field-based initial cleaning machines are the optimal choice, allowing most soil impurities in mechanically recovered residual films to be processed on-site, minimizing disputes.
Simultaneously, the governance of residual film pollution in farmland requires efforts from government management departments. A fee of 30 yuan per acre is required for residual film recovery operations in farmland. Since land belongs to the state, compelling farmers to pay the operation fee necessitates legal regulations and administrative measures. While technical workers cannot take the lead, they can fully cooperate with government departments to make significant technological contributions, enabling large-scale promotion and application.
(The author is an academician of the Chinese Academy of Engineering and a researcher at Shihezi University. This article is based on an interview conducted by reporter Wen Caifei for the Leis Forum.)
