Predictive soil health indicators across a boreal forest to agricultural conversion gradient

A changing climate offers new opportunities to expand agriculture in northern latitudes, and understanding forest-to-agriculture land conversion impacts is critical to ensure soil sustainability. Using the Comprehensive Assessment of Soil Health (CASH) framework, we identified a minimum suite of indicators with little collinearity to reliably predict soil impacts during the conversion of boreal forest to agriculture and a time since conversion gradient (forest, <10 years, >10 and <50 years, and >50 years since conversion). We sampled paired forest and agricultural sites and used multiple linear regression to assess 16 indicators and found four- and six-indicator models predicted the CASH score with varying but reasonable accuracy depending on conversion class. Organic matter, water aggregate stability, and pH were consistent predictors across all classes, as well as one or more micronutrients. The CASH framework appears to be more suitable for agricultural soils and as time since conversion proceeds.