Comment on the paper 'Soil microplastic pollution under different land uses in tropics, southwestern China'.

Research on soil microplastics is currently at an early stage, and there is no widely approved sampling protocol. Even so, any basic research should minimize errors to ensure that they are not amplified in future research. This paper examines some weaknesses of the original research paper 'Soil microplastic pollution under different land uses in tropics, southwestern China' recently published in this journal. The authors neglected to report the equipment used for soil sampling and did not use field blank samples. There is also a soil layer that was incorrectly named. The type and pore size of filter paper used for filtration during pre-analytical soil sample preparation is very important. In this paper the nature of the filter paper used, and its larger pore sizes are questionable by today's scientists. In addition, the authors in the original paper also overlooked reporting the statistical package used for statical analysis and ensuring if all data sets obey normality, homogeneity, and equality before running the one-way ANOVA test. This statistical step is widely considered mandatory, especially in the soil science community. So, this makes it difficult to trust the results documented. Furthermore, in the original paper, the needle and stereo microscope instruments used to sort microplastic-like materials prior to proper analysis are not reliable. [Display omitted] • A dissecting needle and stereo microscope shouldn't be used to sort out soil microplastics. • Gold-coated filter paper with smaller pore size is better than nitrocellulose filter paper. • The 0–10cm is the top soil layer and 10–20cm is the subsoil layer not a deep soil layer. • The statistical package used for analysis must be documented accordingly. • If the dataset is a normal distribution prior to ANOVA testing, it must be confirmed and reported. [ABSTRACT FROM AUTHOR]