Methodological Approaches to the Allocation of Reference Soil Plots on Lands for Various Purposes: Review and Comparative Analysis

The article presents an analytical review of methodological approaches to the allocation of reference soil plots on land for various purposes. The scientific concepts of reference, background, control and reference state of soils used in soil science, agroecology, environmental regulation, pollution monitoring and land degradation assessment are considered. Based on the analysis of domestic and foreign publications, it is shown that the choice of a reference site is determined not only by the degree of soil cover preservation, but also by the category of land, the nature of anthropogenic impact, the objectives of the study and the required level of evidence for conclusions. The main approaches to soil standardization are systematized, including natural genetic, agroecological, background monitoring, expert legal, and restoration and reclamation. The methodological options and limitations of using reference plots in agricultural, forest, urbanized, specially protected and disturbed territories are analyzed. It is shown that the comparative approach is widely used in modern research, however, the criteria of spatial comparability, representativeness and functional adequacy of reference sites remain different. The necessity of a transition from an intuitive choice of background and control sites to a more unified system of choosing soil standards considering genetic, landscape, functional, analytical and legal criteria is substantiated. It is concluded that the reference site should be considered as a special tool for comparative assessment of soil condition, applied differentially depending on the objectives of monitoring, rationing, damage assessment, and land restoration.