Ultrasonication followed by density fractionation is a frequently used method to determine soil structural stability and the amount of occluded particulate organic matter. Our analyses of three soils (sandy, silty and loamy) showed that air drying and gentle rewetting change SOM (soil organic matter) fractions depending on the subsequent time of re-incubation compared to field-fresh samples. This is important, since, e.g., the measurement of archived soils requires the handling of air-dried samples.

The adverse effect of microplastic (MP) on soil biota and soil structure depends on MP particle size and surface characteristics. Since weathering plays a major role in the genesis of these, it must be considered in both the analysis of environmental MP and the production of artificial MP for laboratory experiments. This work integrates recent findings on adverse effects and the genesis of its surface characteristics and discusses how to reproduce them to obtain closer-to-nature designer MP.

Ultrasonication/density fractionation is a common method used to extract particulate organic matter (POM) and, recently, microplastic (MP) from soil samples. In this study, ultrasonic treatment with mechanical stress increasing from 0 to 500 J  mL⁻¹ caused comminution and a reduced recovery rate of soil-derived POMs but no such effects with MP particles. In consequence, the extraction of MP from soils is not affected by particle size and recovery rate artifacts.

Laboratory experiments that assess microplastic (MP) impact on the terrestrial environment require information on common soil MP concentrations. We reviewed item numbers and mass concentrations recorded in 23 studies, with 223 sampling sites in total with respect to the underlying entry pathways, land uses and vicinities. Common values included amounts of up to 13 000 items kg⁻¹ and 4.5  mg kg⁻¹ dry soil. Based on the collected data, we identified problems in past field studies.