Stanislav Sergeevich Ryazanov

The concept of "soil health" has gained significant popularity in scientific literature as a key framework for ensuring ecosystem sustainability. However, the meaning of this term remains ambiguous, and universal assessment criteria are lacking. The aim of this article is to analyze contemporary definitions of "soil health" proposed by domestic and international soil scientists and to review methods for its evaluation. Emphasis is placed on indicators and monitoring systems that claim a degree of universality in diagnosing soil health. According to the European conceptual framework, the term "soil health" should reflect the broad influence of soil cover on ecosystems, including traditionally recognized aspects such as crop productivity, water and air quality regulation, climate regulation, biodiversity conservation, and the provision of social and cultural ecosystem services. In 2021, the European Union adopted a soil development strategy aimed at achieving healthy conditions for all EU soils by 2050. The term "soil health" is expected to be formalized with the adoption of the Soil Monitoring and Resilience Law, which will establish soil health standards. Researchers from Cornell University (USA) have proposed a similar methodology for comprehensive soil health assessment, termed CASH (Comprehensive Assessment of Soil Health). Both systems – CASH and the Soil Monitoring and Resilience Law – are examined in detail in the article. Additionally, the search for a universal soil health indicator continues; the article discusses metrics such as organic matter content, the soil organic carbon-to-clay ratio (SOC:Clay), and its alternatives (Observed/Typical SOC ratio, SOC/SOCexp). A literature review reveals that the rationale for introducing the term "soil health" remains questionable. In practice, "soil health" is almost universally interpreted as a combination of physical and chemical properties that potentially influence soil fertility. Moreover, practices aimed at restoring "soil health" primarily focus on maintaining agronomic soil properties. In this regard, the indicators and methods for assessing "soil health" differ little from those used to evaluate "soil quality". Russian studies tend to explore fundamental aspects of soil system resilience, emphasizing the biological origins and biodynamic essence of soil. Proposed assessment methods are also based on microbiological indicators: thermodynamic characterization of microbial systems, the heterotrophic parameter of soil health, the self-sufficiency parameter for biophilic elements, phytosanitary soil status indicators, and enzymatic activity. The reviewed indicators and monitoring systems demonstrate potential for comprehensive soil diagnostics. However, their universality is limited by variability in soil-climatic conditions and land-use types.