Microplastic contamination in farmyard manures: implications for sustainable agriculture

While extensive research on microplastics has been conducted in aquatic and terrestrial ecosystems, their presence in organic farmyard manures-a key component of agricultural lands-remains largely unexamined. Microplastics are plastic particles less than 5 mm in size, which may originate from the breakdown of larger plastics (secondary) or be produced directly in small sizes (primary). Given the potential of organic farmyard manures to serve as a source of microplastics in agricultural settings, the present study investigated the abundance and characteristics of microplastics in non-commercially prepared farmyard manures using density separation, wet peroxide oxidation, microscopic observation, and ATR-FTIR spectroscopy. The results reveal that these manures are significantly contaminated with both macro- and microplastics. All samples, except one collected from a rural area, showed the presence of microplastics. Five polymer types were identified-polyvinyl chloride, cellulose acetate, polypropylene, polyethylene terephthalate, and polycarbonate-all commonly associated with household and agricultural uses. Consequently, organic farmyard manure cannot be considered completely safe for agricultural use. Assessing fertilizer quality prior to application is essential to prevent soil contamination, and further research is needed to explore this source of microplastics in terrestrial ecosystems.