Changes in Soil Properties Under the Influence of Microplastics in Plastic and Open Field Production in Three Serbian Valleys

Crop production in plastic greenhouses is one of the major sources of plastic pollution worldwide. The main hypothesis of this study is that the regular use of mulch film in greenhouses leads to the cumulative accumulation of microplastic particles (MPs) in the soil, which ultimately leads to changes in the soil properties. Therefore, the main objective of this study was to identify the possible changes in the physical, chemical, and biological properties of soil in greenhouses in three regions of Serbia. The following chemical parameters were determined: electrical conductivity, soil acidity, cation exchange capacity (CEC), total carbon (TC) and nitrogen (TN) content, plant-available phosphorus and potassium content, and trace element content. The following physical parameters were determined: particle size distribution, volumetric mass, specific mass, and porosity; the biological parameters that were determined were microbial respiration and labile carbon. The obtained data were processed using network analysis (NA) to identify the complex relationships between MP content and soil parameters. The NA results support the main findings that the presence of microplastics leads to the destruction of soil structure, which reduces bulk density and increases soil porosity. A strong positive correlation of MPs with soil particles < 0.02 mm and a negative correlation with CEC were found. In the Danube Valley, soil respiration was 78% higher in the open ground compared to a plastic greenhouse. The results contribute to a better understanding of the influence of MPs on soil properties and its ecological functions.