Can biodegradable plastic mulch boost chili yield in Sri Lanka?
Chili is a vital cash crop in many countries, and Sri Lanka is no exception. As one of the pillar industries of the country’s agriculture, chili not only meets domestic consumption needs but also is exported to markets such as India, the Middle East, and Europe in the form of processed products like dried chili and chili powder, supporting the livelihoods of numerous smallholder farmers. However, local farmers have long faced challenges including water scarcity, nutrient loss, and weed competition. Particularly against the backdrop of climate change exacerbating erratic rainfall, yield stability is severely threatened.
To address these issues, plastic film mulching (PFM) has been widely adopted. It promotes crop growth by reducing soil evaporation, regulating temperature, and improving water use efficiency. Nevertheless, the long-term use of traditional non-biodegradable mulches (such as polyethylene mulch) leads to soil microplastic accumulation and ecological pollution. The effectiveness and sustainability of biodegradable mulches in high-rainfall wet zone agriculture have not been fully verified.
So, in ecologically sensitive regions like Sri Lanka’s wet zone, how do different types of plastic mulches affect soil properties and chili yield? Can biodegradable mulch emerge as a viable alternative that balances productivity and environmental protection?
Dr. Mojith ARIYARATNA from the Department of Crop Science, Faculty of Agriculture, University of Peradeniya, Sri Lanka, and his colleagues conducted a field experiment in the country to systematically compare the effects of three types of plastic mulches: black non-biodegradable low-density polyethylene (LDPE) mulch, silver-black reflective LDPE mulch, and polylactic acid-polybutylene adipate-co-terephthalate (PLA-PBAT) biodegradable mulch, with unmulched soil as the control. The experiment lasted for 7 months, covering both dry and wet seasons, and the chili variety cultivated was “MICH HY-1”, which is widely grown locally. Researchers regularly measured soil physicochemical properties and crop growth indicators to evaluate the comprehensive impact of different mulches on chili production. The relevant article was published in Frontiers of Agricultural Science and Engineering (DOI: 10.15302/J-FASE-2025648).
The results showed that all mulch treatments significantly improved soil conditions and crop performance. In terms of soil moisture retention, the gravimetric moisture content (GMC) of mulched groups was higher than that of the control group at multiple key time points. The biodegradable mulch performed particularly well during the dry period; for example, the soil moisture content reached 23.6% at 8 weeks after planting, significantly higher than the control group’s 9.3%. Regarding soil temperature, the black non-biodegradable mulch had the most pronounced warming effect, with the highest temperature reaching 33.3 ℃, while the control group consistently maintained the lowest temperature. This helps promote chili root activity and nutrient uptake.
Nutrient retention is another important function of mulches. The experiment found that mulching effectively reduced the loss of soil nitrate nitrogen (NO3–) and available phosphorus (P), but had no significant effect on ammonium nitrogen (NH4+). In addition, although mulching did not change soil pH, it increased electrical conductivity (EC), indicating an accumulation of soluble salts and nutrients in the soil, which is associated with reduced leaching loss.
In terms of crop growth and yield, the advantages of mulch treatments were more significant. Chili plants under non-biodegradable mulch had the highest plant height; the biodegradable mulch achieved the highest total yield, followed by the reflective mulch and non-biodegradable mulch. Notably, the biodegradable mulch showed stable performance in all harvests, and its final biomass was comparable to that of non-biodegradable mulch, demonstrating its substitution potential in terms of productivity.
This study systematically evaluated the comprehensive performance of biodegradable mulch and traditional mulch in Sri Lanka’s wet zone. Previous studies have mostly focused on arid or semi-arid regions, while data on the effectiveness and environmental risks of mulches under high rainfall conditions in wet zones has been lacking. This research indicates that biodegradable mulch is comparable to non-biodegradable mulch in maintaining soil moisture, nutrients, and crop yield, while avoiding plastic residue problems, providing a feasible solution for sustainable agriculture in tropical high-rainfall regions.
Chili is a vital cash crop in many countries, and Sri Lanka is no exception. As one of the pillar industries of the country’s agriculture, chili not only meets domestic consumption needs but also is exported to markets such as India, the Middle East, and Europe in the form of processed products like dried chili and chili powder, supporting the livelihoods of numerous smallholder farmers. However, local farmers have long faced challenges including water scarcity, nutrient loss, and weed competition. Particularly against the backdrop of climate change exacerbating erratic rainfall, yield stability is severely threatened.
To address these issues, plastic film mulching (PFM) has been widely adopted. It promotes crop growth by reducing soil evaporation, regulating temperature, and improving water use efficiency. Nevertheless, the long-term use of traditional non-biodegradable mulches (such as polyethylene mulch) leads to soil microplastic accumulation and ecological pollution. The effectiveness and sustainability of biodegradable mulches in high-rainfall wet zone agriculture have not been fully verified.
So, in ecologically sensitive regions like Sri Lanka’s wet zone, how do different types of plastic mulches affect soil properties and chili yield? Can biodegradable mulch emerge as a viable alternative that balances productivity and environmental protection?
Dr. Mojith ARIYARATNA from the Department of Crop Science, Faculty of Agriculture, University of Peradeniya, Sri Lanka, and his colleagues conducted a field experiment in the country to systematically compare the effects of three types of plastic mulches: black non-biodegradable low-density polyethylene (LDPE) mulch, silver-black reflective LDPE mulch, and polylactic acid-polybutylene adipate-co-terephthalate (PLA-PBAT) biodegradable mulch, with unmulched soil as the control. The experiment lasted for 7 months, covering both dry and wet seasons, and the chili variety cultivated was “MICH HY-1”, which is widely grown locally. Researchers regularly measured soil physicochemical properties and crop growth indicators to evaluate the comprehensive impact of different mulches on chili production. The relevant article was published in Frontiers of Agricultural Science and Engineering (DOI: 10.15302/J-FASE-2025648).
The results showed that all mulch treatments significantly improved soil conditions and crop performance. In terms of soil moisture retention, the gravimetric moisture content (GMC) of mulched groups was higher than that of the control group at multiple key time points. The biodegradable mulch performed particularly well during the dry period; for example, the soil moisture content reached 23.6% at 8 weeks after planting, significantly higher than the control group’s 9.3%. Regarding soil temperature, the black non-biodegradable mulch had the most pronounced warming effect, with the highest temperature reaching 33.3 ℃, while the control group consistently maintained the lowest temperature. This helps promote chili root activity and nutrient uptake.
Nutrient retention is another important function of mulches. The experiment found that mulching effectively reduced the loss of soil nitrate nitrogen (NO3–) and available phosphorus (P), but had no significant effect on ammonium nitrogen (NH4+). In addition, although mulching did not change soil pH, it increased electrical conductivity (EC), indicating an accumulation of soluble salts and nutrients in the soil, which is associated with reduced leaching loss.
In terms of crop growth and yield, the advantages of mulch treatments were more significant. Chili plants under non-biodegradable mulch had the highest plant height; the biodegradable mulch achieved the highest total yield, followed by the reflective mulch and non-biodegradable mulch. Notably, the biodegradable mulch showed stable performance in all harvests, and its final biomass was comparable to that of non-biodegradable mulch, demonstrating its substitution potential in terms of productivity.
This study systematically evaluated the comprehensive performance of biodegradable mulch and traditional mulch in Sri Lanka’s wet zone. Previous studies have mostly focused on arid or semi-arid regions, while data on the effectiveness and environmental risks of mulches under high rainfall conditions in wet zones has been lacking. This research indicates that biodegradable mulch is comparable to non-biodegradable mulch in maintaining soil moisture, nutrients, and crop yield, while avoiding plastic residue problems, providing a feasible solution for sustainable agriculture in tropical high-rainfall regions.
Journal
Frontiers of Agricultural Science and Engineering
Frontiers of Agricultural Science and Engineering
DOI
Method of Research
Experimental study
Experimental study
Subject of Research
Not applicable
Not applicable
Article Title
Biodegradable and non-biodegradable plastic mulches enhance chili production in Sri Lankan wet zone agriculture
Biodegradable and non-biodegradable plastic mulches enhance chili production in Sri Lankan wet zone agriculture
Article Publication Date
15-Feb-2026
15-Feb-2026
How do biodegradable plastic films affect microplastics and soil microorganisms in paddy fields?
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.
Journal
Frontiers of Agricultural Science and Engineering
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Effect of biodegradable films on microplastic distribution and microbial community composition in paddy soil
Article Publication Date
15-Feb-2026
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