Operationalising the dimensions of soil security assessment for water storing function in Australia

This study assesses the security of the Soil Water Storing Function (SWSF) across Australia by operationalising and combining the five dimensions of soil security: capacity, condition, capital, connectivity, and codification. Utilising the pedogenon mapping concept, we quantified the capacity dimension using available water capacity of reference soils (genosoils), and the condition dimension as the deviation of current state (phenosoils) from the reference state within the top one metre. Capital was estimated via production functions linking plant available water capacity to land value. The connectivity dimension integrated spatially interpolated stakeholder survey data. Codification was scored based on the existence of legislative protections for SWSF. These multi-scalar datasets were synthesised using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) to rank locations based on their geometric distance from an ideal state. The resulting soil security index ranged from 0.26 to 0.75 (mean = 0.59, SD = 0.05). High-security regions (e.g., Northeast regions) were driven by robust condition and governance, whereas low-security areas (e.g., near Nullarbor Plain) were restricted primarily by inherent capacity and capital in some other scattered areas. The analysis identified the restrictive dimension for each mapping unit (pedogenon), the specific factor most limiting soil security. Soil capacity was found as the most widespread restrictive dimension across Australia for SWSF’s security. This research demonstrates an operational framework that moves beyond biophysical health, providing policymakers with a prescriptive tool to target interventions based on combined biophysical, socio-economic, and regulatory risks.