Chitosan as an organic amendment to improve soil properties and plant growth in the presence of polystyrene microplastics

Abstract The widespread usage and production of microplastics (MPs) products has resulted in a surge of plastic waste in the natural environment. Chitosan (CH) is a natural polymer derived from chitin, found in the shells of crustaceans such as shrimp and crabs and studied extensively for its potential use as an amendment. The dynamic interplay between plastic, specifically polystyrene (PS), and the potential of CH as a soil enhancer holds pivotal implications for soil health and crop vitality. While PS seems to wield minimal influence on soil pH, CH demonstrates a distinct ability to lower pH levels significantly. However, the synergy between CH and PS in altering soil pH is relatively limited. Importantly, CH emerges as a compelling countermeasure against the detrimental impact of PS on soil chemistry. Its application brings about promising changes, such as mitigating nutrient depletion and enhancing organic matter (OM). Shifting focus to crop growth, PS emerges as a growth inhibitor, substantially reducing maize biomass and chlorophyll content. Conversely, CH emerges as a growth stimulant, positively affecting root and shoot dry weights, leaf area, and plant height. The interplay between CH and PS manifests complex outcomes on these growth metrics, indicating interdependence. These findings resonate with sustainable soil management practices and the optimization of crop productivity. Further scrutiny is warranted to unravel the underlying mechanisms and long‐term consequences, offering a comprehensive understanding of the interaction between PS, CH, and the ecological landscape. Such insights pave the way for informed decisions in ecological preservation and agricultural sustenance.