Valuing and integrating soil roles in assessing the capital dimension of soil security: An Australian case study

•3 soil roles (functions, services, and threats) were quantified for holistic valuation.•pH regulation costs were estimated to represent a soil threat.•The market prices and soil stocks of OC, N, P, and k were integrated.•Possible benefits obtained from the AWC were calculated.•The results revealed larger values soil capital in eastern Australia and Tasmania. The crucial role of soil in global food production and its multifaceted contributions to ecosystem services underscore the need for a comprehensive evaluation framework. This study presents a novel approach to soil evaluation by integrating the assessment of soil functions, services, and threats into a unified metric which quantifies the capital dimension which is termed "soil management capital". To achieve this, we focused on three key roles: a threat, evaluated by the pH regulation costs, factoring in different buffering capacities and liming/sulphuring treatments to attain an optimal reference pH, a function, representing soil's role as a reservoir and regulator of nutrients; and a service, considering available water holding capacity (AWC) for water security. Integrating these activities culminates in a soil capital metric, providing a comprehensive understanding of the soil's economic value in US$/ha units on a pixel-by-pixel basis across Australia. To achieve this, we analysed spatial information from the Soil and Landscape Grid of Australia (SLGA) with Google Earth Engine (GEE). Our study generated detailed maps illustrating pH regulation costs, OC, nutrients (N, P, K), and AWC across Australia. The integration of these roles revealed regions of large soil capital in the Australian eastern coast and Tasmania.