An integrated approach to assessing soil biological health

Soil health is an emerging field that holistically approaches key challenges within soil science through a chemical, physical, and biological lens. In recent years, soil health has become foundational to sustainability goals within the context of regenerative agriculture including climate mitigation and reversing biodiversity trends. However, given the vast array of indicators used to quantify soil health, there are still several unknowns regarding which indicators can most effectively indicate specific soil health outcomes and ecosystem functioning. Key linkages between indicators and soil health outcomes are especially lacking in the subfield of soil biological health. Moreover, the subfield of soil biological health, must expand its current portfolio of indicators to play an active role in soil biodiversity assessments. Here we propose an integrative approach to quantitatively assess soil biological health. We outline numerous key indicators that are important to consider because of their position in the soil food web and linkages to key soil processes. We recommend that future soil health assessments directly measure soil organisms in conjunction with indicators that reflect key ecosystem functions. Exploratory factory analysis, a powerful quantitative method, for integrating soil biological health indicators is also discussed.