A recent study published in Frontiers of Agricultural Science and Engineering highlighted the ecological effects of traditional and biodegradable microplastics on agricultural ecosystems, mainly focusing on pea (Pisum sativum) growth and soil health. Researchers investigated how different types and concentrations of microplastics affect soil microbial activity, nutrient availability, and plant development across key growth stages: seedling (15 days), flowering (27 days), and maturity (41 days).
The findings suggest that microplastics can negatively impact soil health and crop productivity, raising concerns about plastic pollution in agriculture and highlighting the importance of sustainable farming practices.
Image Credit: Arpon Pongkasetkam/Shutterstock.com
The Challenge of Microplastic Pollution
Microplastics, particularly those under 5 mm, pose a significant threat to soil health and ecosystem function. Agricultural soils have become major reservoirs of microplastics, primarily from plastic mulch films. These particles can alter soil properties, disrupt microbial communities, and interfere with nutrient cycling and plant growth.
Traditional microplastics such as polypropylene (PP) and polyethylene (PE) resist degradation and accumulate in soils, threatening soil quality and crop yields. To address this issue, biodegradable options such as polycaprolactone (PCL) and polybutylene adipate terephthalate (PBAT) have been developed. While designed to break down more easily, they may still affect microbial diversity and nutrient dynamics. The comparative effects of traditional and biodegradable microplastics across different plant growth stages remain underexplored, as most research focuses on single stages or specific plastic types.
Exploring Microplastic Effects on Pea-Soil System
Researchers conducted a controlled microcosm experiment to examine how traditional and biodegradable microplastics affect pea growth and soil nutrient processes at each individual stage. Soil samples were collected from an agricultural park in Zhejiang Province, China. Microplastics with a uniform particle size (~125 µm) were mixed into the soil at two concentrations: 0.1% and 1% (w/w), simulating field-relevant contamination levels.
Nine groups, including a control without microplastics, were tested with nine replicates each. Pea seeds were germinated in treated soils, and plants were grown under controlled conditions. Soil and plant samples were collected at each growth stage for analysis.
Measured soil parameters included dissolved organic carbon (DOC), ammonium, nitrate, and Olsen phosphorus. Microbial biomass carbon (MBC), nitrogen (MBN), and phosphorus (MBP) were quantified. Enzymatic activities of key soil hydrolases and oxidases, including β-glucosidase (BG) and β-cellobiohydrolase (CBH), were assessed to evaluate nutrient cycle.
Additionally, microbial diversity and community structure were analyzed using high-throughput sequencing of bacterial 16S rRNA and fungal ITS regions. Structural equation modeling (SEM) was also used to explore causal links among microplastic types, concentration, microbial metrics, soil enzymes, nutrient availability, and pea biomass.
Effects of Microplastics on Pea Growth
The study demonstrated stage-specific effects of microplastic type and concentration on pea shoot and root biomass. At the seedling stage, 1% PP reduced shoot biomass by 43.4%, while 0.1% PBAT increased root biomass by 35.3%. During flowering, shoot biomass increased by 126.1% with low-dose PP, 88.0% with PE, and 103.0% with high-dose PBAT. At maturity, most microplastic treatments enhanced shoot biomass by 72.5% to 193.0%, except for 1% PCL; root biomass also rose significantly with 1% PP, PE, and PBAT.
Soil nutrient analyses revealed lower DOC levels in microplastic-treated soils at the seedling stage, indicating that microplastics may bind organic matter and inhibit decomposition. Nitrate levels increased with PCL at the seedling stage but declined with PP, PE, and PBAT at maturity. Biodegradable microplastics, particularly PCL and PBAT, elevated microbial biomass (MBC, MBN, MBP) across stages, suggesting they stimulate microbial activity.
Enzyme assessments showed higher activities of carbon-acquisition enzymes (BG, CBH) in low-dose biodegradable treatments, especially during early growth stages. Furthermore, microbial diversity analysis indicated increased bacterial diversity with low-dose microplastics at the seedling stage, while fungal diversity remained unchanged.
Implications for Sustainable Agriculture
This research has significant implications for agriculture and plastic waste management. It suggests that using biodegradable microplastics like PBAT may improve crop growth and soil health, offering a sustainable alternative to conventional plastics. Such practices could help reduce the environmental impact of plastic use in farming.
The findings inform agricultural management decisions regarding plastic mulch use, advocating for careful evaluation of biodegradable plastics’ ecological safety before widespread adoption. The study emphasizes the importance of considering crop growth stages to optimize microplastic application and mitigate adverse effects.
Conclusion and Future Directions
Traditional and biodegradable microplastics significantly affect pea growth and soil health. Biodegradable microplastics, mainly PBAT, showed potential to improve nutrient cycling and crop performance. However, concerns remain about their long-term effects. As plastic pollution escalates, adopting sustainable materials in farming becomes critical.
Future work should prioritize longer field trials, particularly with legumes like peas that rely on biological nitrogen fixation, to fully assess how microplastics affect soil health, microbial activity, and crop productivity. Understanding interactions among microplastics, root exudates, and microbial communities across multiple seasons will be key to developing sustainable plastic use strategies in agriculture.
Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.
Source:
Wu, J., Liu, Y., Wang, L., Xiao, M., Wei, L., Ding, J., Chen, J., Zhu, Z. & Ge, T. (2025) Traditional and biodegradable plastics improve pea (Pisum sativum) growth by promoting nutrient turnover in soil. Frontiers of Agricultural Science and Engineering, 13(1), p.25626. Available at: https://doi.org/10.15302/J-FASE-2025626