Plastic pollution has become a globally recognized environmental issue, with agricultural increasingly serving as a significant reservoir for microplastics due to the widespread use of plastic films. These tiny plastic fragments can alter soil structure, disrupt microbial activity, and interfere with nutrient absorption in plants, thereby threatening the health of agricultural ecosystems. In recent years, biodegradable plastics have been viewed as potential alternatives to traditional plastics, but what are the differences in their impacts on agricultural fields? Which type is more beneficial for the health of the crop-soil system?
Recently, a research team led by Dr. Tida Ge from Xinjiang University and Ningbo University conducted a pot experiment to explore this question. The study selected peas as the experimental crop and examined two types of microplastics: traditional microplastics (polypropylene (PP) and polyethylene (PE)) and biodegradable microplastics (polycaprolactone (PCL) and polybutylene adipate terephthalate (PBAT)). These were added to the soil at doses of 0%, 0.1%, and 1% (w/w) to observe the growth status of peas during three critical growth stages: seedling, flowering, and maturity. The study also analyzed soil nutrients, microbial activity, and community changes. The study has been published in Frontiers of Agricultural Science and Engineering ( DOI: 10.15302/J-FASE-2025626 ).
The experimental results indicated significant differences in the effects of different types and doses of microplastics on pea growth. Notably, the biodegradable microplastic PBAT showed certain advantages during the seedling stage—soils with 0.1% PBAT saw a 35.3% increase in root biomass compared to the control group. This may be related to PBAT's ability to stimulate microbial growth, allowing roots to "mine" more available nutrients. In contrast, the effects of traditional microplastics PP and PE on the above-ground parts of the peas were more complex: seedlings treated with 1% PP experienced a 43.4% decrease in above-ground biomass, whereas 0.1% PP led to a 126.1% increase in biomass during the flowering stage. Similarly, treatments of 0.1% and 1% PE resulted in 88.0% and 68.7% increases in above-ground biomass during flowering, respectively. These differences may be attributed to the physical properties of traditional microplastics and their effects on soil structure.
From a soil ecology perspective, biodegradable microplastics, as easily decomposable carbon sources, can increase the carbon, nitrogen, and phosphorus content within soil microorganisms, promoting organic matter decomposition and nutrient cycling. Traditional microplastics, being more difficult to degrade, provide additional habitats for microorganisms through soil aggregation, but their impact on microbial biomass is less stable. Moreover, all microplastic treatments increased the complexity of bacterial and fungal networks without significantly altering material exchange between microorganisms, although this may have potential implications for ecological functions. The study also found that when the easily degradable carbon in microplastics was exhausted by microorganisms, the fresh carbon secreted by pea roots was insufficient to alleviate microbial "carbon hunger". At this point, peas and microorganisms would compete for limited nitrogen and phosphorus resources in the soil, which could be a significant reason for adjustments in pea growth strategies later on.
Although the experiment revealed the short-term effects of different microplastics on the pea–soil system, the research team emphasized that the long-term toxicity of microplastics has not yet fully manifested due to the short experimental duration. Future studies should involve longer-term field experiments, particularly focusing on leguminous crops that rely on biological nitrogen fixation, to further assess the potential risks of microplastics to agricultural ecosystems.
