Microplastic contamination in agricultural soils: occurrence, polymer characterization, and ecological risk in banana farmlands of Southwestern India

Microplastic pollution has been widely studied in aquatic environments, but limited evidence is available on its presence in agricultural soils, especially in India. Farmlands are increasingly exposed to plastic debris through irrigation, fertilizers, mulching materials, and other human activities. Understanding the occurrence and characteristics of microplastics in soil is critical for assessing potential ecological and agricultural risks. This study investigates the presence, types, and possible sources of microplastics in banana farmland soils of Kasaragod District, Kerala. A total of sixteen soil samples were collected in the month of February from banana cultivation areas in triplicates (n = 48). Microplastic contamination was confirmed in all samples, with concentrations ranging from 19.17 to 319.17 particles per kilogram of soil, and an average of 137.19 particles per kilogram of dry soil. Morphological analysis by microscopy revealed that fibres were the most dominant form (72%), followed by fragments (15%), microbeads (10%), and films (3%). Most of the particles black, blue, and red being the prevalent colours, with possible inputs from both agricultural and domestic sources. Polymer identification using Fourier transform infrared spectroscopy confirmed polypropylene (70%) and polyethylene (30%) as the main polymers. Pollution hazard index analysis suggested that all sites posed medium to high ecological risk with the highest PHI value recorded as 1100. Statistical analysis demonstrated significant differences in microplastic abundance among locations, and correlation analysis indicated a strong association between fibre particles and coloured microplastics, highlighting their link to human activities. This study provides the first documented evidence of microplastic contamination in banana farmland soils in India. The findings demonstrate that agricultural soils can act as an important sink for microplastics and are vulnerable to ongoing plastic deposition from multiple sources. The dominance of coloured microplastic fibres suggests substantial anthropogenic contributions. The observed ecological risks underscore the urgent need for improved management of plastic waste, better agricultural practices, and stronger regulatory measures to protect soil quality and ensure sustainable farming systems. This highlights the critical need for integrating sustainable plastic management strategies within agricultural practices to prevent long-term soil degradation and ensure food security.