Physical, Chemical and Biological Properties of Soil and their Relationship with Soil Health: A Critical Review

Abstract

Soil is one of the most functionally complex components of any terrestrial ecosystem, mediating nutrient cycling, water purification, carbon storage, and food production on a planetary scale. Yet soil health itself—understood here as the sustained capacity of soil to function as a living system that supports plant and animal productivity while maintaining or improving environmental quality—remains a concept that has proved difficult to pin down with precision. This critical review draws together evidence from three interlocking property domains: physical properties such as texture, structure, bulk density and water dynamics; chemical properties spanning pH, organic matter, nutrient availability, cation exchange capacity and contamination; and biological properties, including microbial community diversity, soil fauna, enzyme activity and mycorrhizal networks. Together, these properties drive the functions that define soil health, among them aggregate stabilisation, carbon sequestration, nutrient cycling and resilience to disturbance. A recurring theme in the literature reviewed here is that no single domain, taken on its own, can adequately describe soil health; the most informative assessments are those that explicitly account for the interactions among all three domains at once. Evidence from global meta-analyses and comparative field studies points consistently to the same conclusion: intensive land management—continuous tillage, heavy reliance on synthetic inputs, monocultural cropping, and repeated heavy machinery traffic—erodes physical structure, depletes organic carbon stocks, narrows microbial diversity, and ultimately weakens the soil's capacity to deliver ecosystem services. By contrast, practices such as cover cropping, reduced tillage, organic amendments and diversified rotations have repeatedly been shown to restore soil function across several of these dimensions simultaneously. The review closes by identifying the principal gaps that remain in this field, including the need for context-sensitive minimum datasets, monitoring frameworks capable of capturing change over meaningful timescales, and more equitable access to emerging sensing and molecular technologies as they are folded into global soil health reporting.