In agricultural production, microplastics have become environmental pollutants that cannot be ignored. They may not only enter the food chain through the soil-plant system, threatening food safety, but also alter the physical and chemical properties of soil, interfere with microbial functions, and thereby affect soil health and crop growth. Traditional non-degradable plastic films are one of the main sources of microplastics in farmland. However, after long-term use, such films will gradually break down due to sunlight, microbial action, and mechanical wear, forming a large amount of microplastics that remain in the soil. To alleviate this problem, biodegradable plastic films have been widely promoted in recent years. Theoretically, such films can be decomposed by microorganisms in the natural environment, reducing plastic residues, but there are still controversies in practical applications: Can biodegradable plastic films really reduce the accumulation of microplastics? Will their degradation process change the characteristics such as particle size and morphology of microplastics in the soil? More importantly, what impact will they have on the soil microbial community involved in microplastic degradation? These issues are directly related to whether biodegradable plastic films can become truly “environmentally friendly” agricultural alternatives.
As the world’s major rice-producing country, China’s paddy field ecosystem is crucial to food security. However, for a long time, to increase yields, many paddy fields in southern China have adopted plastic film mulching technology to retain water and increase temperature, which also makes paddy fields a key area of concern for microplastic pollution. Against this background, Professor Rui Jiang from Soochow University and her colleagues conducted an empirical study on typical paddy fields in southern China. By comparing two types of soils—those with long-term use of biodegradable plastic films (BF) and those with no use of plastic films (CK)—they studied the core issue of “how biodegradable plastic films affect the distribution of microplastics and microbial degradation functions in paddy fields”. The relevant article was published in Frontiers of Agricultural Science and Engineering, Volume 13, Issue 1 (DOI: 10.15302/J-FASE-2025629).
The study first focused on the morphological code of microplastics. The results showed that there were significant differences in the distribution characteristics of microplastics between the two types of soils: in the soil with biodegradable plastic films, the number of microplastics with a particle size of 0.25–0.1 mm was significantly higher; in terms of morphology, there were more film-like microplastics in the soil with biodegradable plastic films, while the soil without plastic films was dominated by fibrous microplastics. This indicates that the degradation process of biodegradable plastic films does change the appearance of microplastics—it tends to form smaller and thinner film-like fragments.
However, the study found no significant difference in the total content of microplastics between the two types of soils. This means that biodegradable plastic films do not increase the total amount of microplastics due to their own degradation; instead, they may promote the conversion of microplastics into simpler structures through a more efficient degradation process.
Through gene sequencing, the research team found that although there was no significant difference in the diversity of microorganisms involved in microplastic degradation between the soil with biodegradable plastic films and the soil without plastic films, the division of labor structure of the microbial community was quite different. Further analysis revealed that a total of 26 functional genes and 10 microbial genera were directly related to the degradation of major polymers.
More importantly, the preferences of different microorganisms for different polymers also changed due to the use of biodegradable plastic films. For example, in the degradation of polystyrene (PS), the genus Nocardioides contributed about 9% in the soil without plastic films, but dropped to 5% in the soil with biodegradable plastic films; in the degradation of polyethylene, the contribution of the genus Bradyrhizobium was more prominent in the soil with biodegradable plastic films compared to the soil without plastic films. These changes indicate that biodegradable plastic films improve the degradation efficiency of microplastics by reshaping the structure of the microbial community.
This study shows that biodegradable plastic films not only have the yield-preserving advantages of traditional plastic films, but also reduce the environmental risks of long-term accumulation of microplastics through synergistic effect with soil microorganisms, providing important scientific support for the sustainable application of biodegradable plastic films.
DOI: 10.15302/J-FASE-2025629