Geospatial Assessment of Soil–Biosphere Nexus Using a Biophysical Soil Security Matrix: Evidence from Minnesota, USA

The soil-biosphere nexus is a critical component embedded in the concepts of soil security and ecosystem services (ES) and is directly linked to several global challenges identified by the United Nations (UN). Although soil security has been proposed as a policy framework, a major problem is that there are no standard procedures to assess the five dimensions of soil security: capability, condition, capital, connectivity, and codification in relation to the soil-biosphere nexus. This study proposes a land cover change matrix, disaggregated by soil type (“biophysical soil security matrix”), as a tool to evaluate the biophysical soil security continuum and its temporary changes, integrated with ES valuation. The matrix was tested using the state of Minnesota (MN) as a case study. Although the dominant soil orders in MN possess high natural capability, widespread human-caused land degradation has dramatically lowered their actual biophysical condition and has fueled massive soil decarbonization. Historic land degradation in MN due to human activity totaled 98,516 km2 through 2024, with nearly 480 km2 of anthropogenically degraded land created between 2001 and 2024. Based on carbon emissions alone, we estimate that historic land degradation in MN has resulted in total social costs of nearly $50B (U.S. dollars, B = billion = 109) through 2024, with about 10% of this total social cost being realized between 2001 and 2024. Trends like this threaten soil security by directly eroding the soil’s capacity to sustain ES. Based on the analyses and results, this study recommends conducting both soil-centric and human-centric analyses of soil security to ensure the sustainable use of soil.