Soil organic matter (SOM) is an important store of carbon and is vital to maintaining soil health. Growing crops generally causes a reduction in SOM. However, organic farming systems often adopt practices that partially mitigate this loss. Biodegradable plastic film mulch (PFM) can increase yields by improving soil hydrothermal conditions, increasing nitrogen use efficiency and suppressing weeds. It can also speed up SOM breakdown and induce changes to the soil microbiome. Further, the increased return of C from rhizodeposition and crop residues from PFM-grown crops can compensate for SOM breakdown, although outcomes vary substantially with agronomic and environmental conditions. To address these uncertainties, a plot-scale field experiment was conducted on an organic farm with a 3-year vegetable rotation measuring SOM content from treatments with and without biodegradable PFM, inputs of poultry manure or green waste compost, and with or without an overwinter green manure. Biodegradable PFM caused a significant increase in yield in all the crops grown (43%–46%) and the overwinter green manures (18%), resulting in more organic matter incorporated into the soil. Despite this, there was no significant difference in the SOM content between the biodegradable PFM- and non-PFM-mulched plots over the 3 years, nor was there any significant change in soil bacterial diversity. In contrast, the large difference in the mass of green waste compost and poultry manure addition resulted in a 15% increase in SOM after 3 years. Biodegradable PFM did not affect alpha (Shannon) or beta diversity of soil bacterial community.
In the context of food security and the greening of agriculture, the sustainable management of agricultural plastics is critical. Although essential to agricultural production, agricultural plastics pose significant environmental risks, particularly in the waste management phase, requiring urgent intervention. Source reduction and effective recycling are key solutions. Based on a systematic review of policy documents, this study analyzed the evolution of China’s agricultural plastics management policies. This policy framework has progressed through three stages. The first stage focused on increasing production and promoting technology, leading to widespread adoption of agricultural plastics but weak environmental regulation. In the second stage, policies began balancing production growth with environmental protection, with stronger environmental regulations and regional successes, but nationwide systematic management remains inadequate. The third stage emphasizes agricultural sustainability, promoting life-cycle management and regionally differentiated management. Although recycling rates have improved significantly, a long-term sustainable management mechanism is still lacking, and there are many challenges to source reduction and effective recycling. Based on this analysis and incorporating international experience, a set of key strategies is proposed for sustainable management, including establishing a unified national framework with region-specific programs, advancing technological innovation and adoption, and integrating environmental regulations with market mechanisms.
Microplastic accumulation caused by traditional plastic mulching can disturb plant nutrient-mining strategies. Biodegradable plastics may reduce these risks. However, the different effects of traditional and biodegradable microplastics on agroecosystems and optimal microplastic type for crop-soil systems remain largely unknown. A pot experiment was performed to identify the mechanisms underlying the effects of traditional [polypropylene (PP) and polyethylene (PE)] and biodegradable [polycaprolactone (PCL) and polyadipate/butylene terephthalate (PBAT)] microplastics at 0%, 0.1% and 1% (w/w) in a pea-soil ecosystem. Traditional microplastics caused greater carbon allocation to shoots, while PBAT did not significantly alter dissolved organic-carbon content. NH4+-N increased with 1% (w/w) PP whereas NO3–-N decreased owing to enhanced N-acetylglucosaminidase activity with 0.1% and 1% PP and PE, and 1% PBAT during pea growth. Biodegradable microplastics enhanced microbial biomass carbon, nitrogen and phosphorus, whereas traditional microplastics gave inconsistent results. Microplastics increased the complexity of bacterial and fungal networks and impacted ecosystem functions because they may serve as labile carbon resources for soil microorganisms, stimulating organic matter decomposition. However, once labile carbon in native soils is depleted, inadequate fresh labile carbon from root exudates fails to alleviate microbial carbon limitations, resulting in peas competing with microorganisms for scarce nitrogen resources to promote its growth.
The global use of agricultural plastic film has severely impacted the ecosphere due to their non-biodegradability, unsafe disposal and limited recyclability. This study aimed to investigate how farmers use agricultural plastic film, including plastic mulch and plastic covers and manage their disposal. The study was conducted in three governorates of Egypt: Dakhalia, Giza and Minya. Data were collected through stratified proportional random sampling based on farm size, surveying 300 farmers managing four plasticulture systems: plastic mulch in open fields, net houses, low tunnels and high tunnels. The data were collected through face-to-face interviews using a structured questionnaire. The study findings reveal that plastic mulch residuals are often burnt in the open or plowed back into soil matrix, whereas plastic film covers are typically collected for recycling. Also, farmers identified the lack of recycling facilities and the absence of fixed disposal locations as the main obstacles for proper plastic waste management. The regression analysis findings also showed the main factors positively affecting the plastic mulch recycling behavior of farmers, including farm size, farm ownership, family member participation in agriculture, and years of experience with plasticulture systems. The findings provide valuable insights for policymakers to develop collaborative management strategies for plastic disposal and recycling, aiming to reduce the environmental risks of microplastics in terrestrial ecosystems.
Agricultural plastic mulch film represents a significant source of microplastic contamination in soils, raising concerns about soil health and food security. Oxo-degradable plastics (ODPs) have emerged as a potentially more sustainable alternative to current plastic mulch films, however, uncertainty remains around the degradation rate of ODPs in soil and their impacts on soil quality and crop health. The study evaluated the dynamics and impact of different concentrations of micro- and macroplastics derived from a commercial d2w ODP (0.01%, 0.1%, 1% and 10% w/w) on the growth of Zea mays in an agricultural soil over a 6-week period. Chemical analysis revealed the ODP contained about 0.29% additives by weight, primarily comprising antioxidants (tris(2,4-di-tert-butylphenyl) phosphite and its oxidized form) and lubricants, with minimal heavy metal content. ODP degradation was mainly limited to chain scission and had only partial formation of oxygenated groups, without an increase in carbonyl groups. The rate of ODP degradation was found to be inversely related to the ODP concentration in soil. Overall, typical field levels of plastic contamination (0.01% w/w) had negligible effect on soil quality or plant performance. However, higher levels of ODP contamination resulted in significant changes in soil pH, EC, NO3− and bulk density. At extreme plastic loading rates (10% w/w), both micro- and macro-sized ODPs caused significant reductions in plant growth, with microplastic treatments having consistently greater effects than the macroplastic treatments. Changes in bacterial 16S rRNA community composition were driven by Acidobacteriota and Gemmatimonadota. Macroplastics significantly altered these bacterial communities, while microplastics had minimal effect. These findings indicate that at realistic field concentrations, ODPs are likely to have little effect on agroecosystem functioning in the short-term but might persist in soil for long periods of time, leading to their progressive accumulation in agricultural soils if used over repeated cropping cycles.
This study investigated the residual plastic film and microplastic (MP) dynamics in cotton fields of Xinjiang after 5–30 years of mulching. Long-term mulching not only caused continuous accumulation of residual films and MPs but also triggered nonlinear accumulation dynamics. When residual film mass exceeded the critical threshold of 160–200 kg·ha–1, the MP generation rate increased significantly (by 85%), a phenomenon termed the critical effect. Residual films (manually collected) and MPs (extracted by density separation) had cumulative increases with mulching duration, reaching 127, 85.8 and 67.9 kg·ha–1 for films, and 10.8 × 103, 9.75 × 103 and 6.34 × 103 fragments kg−1 for MPs at depths of 0–1, 10–20, and 20–30 cm after 30 years. MPs had surface enrichment but also migrated downward, with < 1 mm fragments increasing from 7.9% to 22.6% to depth, while > 2 mm fragments declined from 49.2% to 13.8%. A strong linear correlation (R2 = 0.85–0.94) confirmed residual films as the primary MP source. Beyond the 200 kg·ha–1 threshold, MP accumulation rates accelerated sharply, highlighting fragmentation risks and vertical migration in arid soils. Timely residue removal before reaching critical thresholds is crucial to mitigate soil MP pollution. These findings provide actionable strategies for managing plastic-intensive agroecosystems, emphasizing proactive intervention to disrupt the critical effect and its cascading environmental impacts.
Biodegradable plastic film (BF) has been widely used in agriculture owing to concerns over microplastic (MP) contamination and its potential risks to agricultural sustainability. Elucidating the distribution of MP and the role of microbial communities in their biodegradation is crucial for evaluating the effectiveness of BF in paddy soil. In this study, soil samples were collected from typical paddies in southern China. The MP composition was analyzed by Fourier-transform infrared spectroscopy. Metagenomic sequencing was conducted to identify MP degradation genes and characterize microbial communities. The results revealed that BF-mulched soil had significantly higher MP abundance in the 0.25–0.1 mm size range than soil with a history of no film use as a comparator (CK) (P < 0.05). Similarly, BF had a significantly higher abundance of particular MP types than the CK (P < 0.05). Five main types of MP biodegradation pathways were identified in both BF and CK samples. Over 26 functional genes and 10 genera were associated with the biodegradation of the top five polymer types. However, only a subset of genes and genera significantly differed between BF and CK samples, particularly in the degradation of di(2-ethylhexyl) phthalate, polyethylene and other polymers (P < 0.05). At the functional level, similar genera contributed to MP degradation. However, the relative contributions of these genera varied depending on the polymer type. Overall, BF use led to more efficient MP degradation into simpler structures than in CK. Although the total MP content did not significantly differ between BF and CK samples, BF use had altered the composition and abundance of MP-degrading bacterial communities in the sampled paddy soil. This enhanced biodegradation efficiency under BF use further supports agricultural sustainability in paddy systems.
Plastic film mulching (PFM) enhances plant growth and productivity by modifying soil properties. In Sri Lanka, the adoption of PFM is gradually rising, especially for high-value crops. However, its influence on soil remains a topic of significant scrutiny, especially in environmentally delicate locations such as the wet zone (WZ) of Sri Lanka. This research examines how different PFMs affect soil physicochemical properties and plant performance in chili production within the WZ. Chili (Capsicum annuum cv. MICH HY-1) was cultivated under a non-biodegradable low-density polyethylene (LDPE) mulch (PEUK), a reflective LDPE mulch, a PLA-PBAT biodegradable mulch (BD) and no mulch film application for one growing season. Soil physicochemical properties (pH, EC, moisture, nutrients and temperature), plant height and leaf chlorophyll content (SPAD) were measured monthly. The fresh biomass of roots, leaves, stems and remaining fruits was measured at the end of the season. This study demonstrated that mulching effectively conserved soil NO3– and available P while having no significant impact on NH4+ levels. Mulching increased gravimetric moisture content (GMC) and soil temperature compared to the control, with PEUK achieving the highest soil temperature (36.3 ± 0.71 °C). Mulching did not influence soil pH, but the control consistently had the lowest EC (17.6 ± 1.54 µS·cm−1). Mulching significantly improved plant height (PEUK of 70.2 ± 1.7 cm), SPAD (PEUK of 65.6 ± 1.4), yield (BD of 1230 ± 84 g) and fresh biomass relative to the control (height of 58.8 ± 2.3 cm, SPAD of 49.7 ± 1.5 and yield of 736 ± 59 g). Overall, the findings demonstrate that biodegradable mulch performed similarly to non-biodegradable plastic mulches in improving both soil properties and crop yield, indicating it could be a sustainable alternative for chili production in wet tropical regions.
Plastic film mulching (PFM) significantly enhances crop yield and quality by increasing soil temperature, reducing water evaporation and optimizing nutrient cycling. However, improper management of plastic film residues has led to microplastic pollution in farmland, posing a major challenge to sustainable agricultural development. The accumulation of microplastics in soil not only affects soil structure but also profoundly impacts crop growth and ecosystem stability by altering nitrogen-related microbial activities and nitrogen (N) cycling processes. This review synthesizes the effects of PFM and microplastics on soil N pools and cycling, exploring their mechanisms in plant N uptake, microbial immobilization, gaseous emissions (e.g., NH3 and N2O), and N transformation processes (e.g., N fixation, assimilation, mineralization, nitrification and denitrification). Research indicates that PFM and microplastics significantly influence N processes by modifying soil physicochemical properties and microbial community structure, although their effects vary depending on plastic type, environmental conditions and crop growth stages. Future studies should further investigate the long-term ecological impacts of microplastics in complex natural environments and employ advanced statistical methods and models to quantify their dynamic effects on N cycling.
Plastic mulch film (PMF) can release microplastics (MPs) and phthalate esters (PAEs) into agricultural soils. These materials can contaminate the food chain, thereby posing a potential risk to human health. However, inconsistent methodologies hinder cross-regional comparisons of MP and PAE concentrations in agricultural soils, preventing an accurate assessment of the actual risk. To address this knowledge gap, a harmonized analysis of MPs and PAEs was conducted in soil across nine typical mulching region in six provinces of China (Gansu, Inner Mongolia, Liaoning, Shandong, Xinjiang and Zhejiang). The results showed that the abundance of MPs in the 0–30 cm soil layer ranged from 2.4 × 106 to 1.5 × 107 items m−2 (equivalent to 5.5 × 103 to 4.9 × 104 items kg−1 soil), with the highest abundance in Shandong and the lowest in Xinjiang. These MPs were mainly composed of rubber, polyolefin, polyester, resin, polystyrene, fluoropolymer, polyamide and polyurethane, of which polyolefin (primarily PMF-derived) accounted for up to 35%. Additionally, six PAEs (di(2-ethylhexyl) phthalate, diisobutyl phthalate, dibutyl phthalate, di-n-pentyl phthalate, diethyl phthalate and dimethyl phthalate) were detected, with total residues ranging from 3.6 to 22.3 mg·kg−1. It was estimated that the total PAE input from PMF constitutes < 0.1% of the measured PAEs at all the sampling sites. Overall, these findings indicate that PMFs are not the main contributor to MP and PAE contamination in agricultural soils under continued PMF application. While removal and recycling of PMF is essential in reducing PMF-derived MP accumulation in soil, further research into other sources is required to establish impactful mitigation strategies and regulations.