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Comparing the impact of microplastics derived from a biodegradable and a conventional plastic mulch on plant performance
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Researchers directly compared how microplastics from biodegradable and conventional plastic mulch films affect plant growth and found that biodegradable plastic particles actually reduced plant biomass more than conventional plastic particles in some cases. This challenges the assumption that biodegradable plastics are always safer for agriculture, since their breakdown products may still harm crops that end up in the human food supply.
Agricultural lands have been identified as plastic sinks. One source is plastic mulches, which are a source of micro- and nano-sized plastics in agricultural soils. Because of their persistence, there is now a push towards developing biodegradable plastics, which are designed to undergo (partial) breakdown after entering the environment. Yet, limited research has investigated the impacts of both conventional and biodegradable plastics on distinct plants. Moreover, comparisons among studies are difficult due to differences in experimental design. This study directly compares the effects of artificially weathered conventional polyethylene (PE) and starch-based biodegradable polybutylene adipate terephthalate (PBAT) on four food crops, including two monocots (barley, Hordeum vulgare, and wheat, Triticum aestivum L.) and two dicots (carrot, Daucus carota, and lettuce, Lactuca sativa L.). We investigated the effects of environmentally relevant low, medium, and high (0.01 %, 0.1 %, 1 % w/w) concentrations of PE and starch-PBAT blend on seed germination (acute toxicity), and subsequently on plant growth and chlorophyll through a pot-plant experiment (chronic toxicity). Germination of all species was not affected by both plastics. However, root length was reduced for lettuce and wheat seedlings. No other effects were recorded on monocots. We observed a reduction in shoot length and bud wet weight of carrot seedlings for the highest concentration of PE and starch-PBAT blend. Chronic exposure resulted in a significant decrease in shoot biomass of barley and lettuce. Additionally, a positive increase in the number of leaves of lettuce was observed for both plastics. Chlorophyll content was increased in lettuce when exposed to PE and starch-PBAT blend. Overall, adverse effects in dicots were more abundant than in monocots. Importantly, we found that the biodegradable plastic caused more commonly adverse effects on plants compared to conventional plastic, which was confirmed by a mini-review of studies directly comparing the impact of conventional and biodegradable microplastics.
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Microplastic exposure reduces plant biomass and chlorophyll content with no detectable safety advantage for biodegradable polymers
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This review pooled data from 31 studies and found that microplastics, whether "regular" plastic or the biodegradable kind used in eco-friendly farm mulch films, both shrink plant growth by about 19% and reduce chlorophyll (the stuff plants need for photosynthesis) by a similar amount. The "biodegradable" plastics didn't turn out to be any safer for crops, meaning swapping to them may not actually protect our food supply from plastic pollution like many assume. Since these microplastics build up in soil where our food grows, this matters for anyone hoping that "biodegradable" labels guarantee a health
The long-term uncertainty of biodegradable mulch film residues and associated microplastics pollution on plant-soil health
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This study investigated the long-term effects of biodegradable mulch film residues and their associated microplastics on soil health and plant growth. Researchers found that as biodegradable films break down faster than conventional plastics, they may actually generate more microplastics in a shorter timeframe. The results raise concerns that biodegradable mulch films, often promoted as eco-friendly alternatives, could pose their own risks to agricultural soil ecosystems.
Microplastics in agroecosystem – effects of plastic mulch film residues on soil-plant system
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This review examines how residues from both conventional polyethylene and biodegradable plastic mulch films accumulate in agricultural soils and affect plant growth and soil health. Both types of mulch film residues are found to have negative effects on the soil-plant system, raising questions about the environmental safety of biodegradable plastic alternatives.
Effects of microplastics derived from biodegradable mulch film on different plant species growth and soil properties
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Researchers studied how microplastics from biodegradable mulch film affect the growth of five different crop species in soil. They found that cabbages and strawberries were most sensitive, with reduced growth at higher microplastic concentrations, while other crops showed little effect. The findings suggest that even biodegradable plastics can break down into microplastics that may harm certain agricultural crops.
Soil biota modulate the effects of microplastics on biomass and diversity of plant communities
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Researchers used mesocosm experiments with natural soil biota to compare the effects of biodegradable and non-biodegradable microplastics on plant community biomass and diversity. Soil biota modulated the impact of microplastics, with biodegradable plastics showing similar effects to conventional plastics on plant community structure, challenging the assumption that biodegradable alternatives are environmentally benign.
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