Evaluation of the Soil Health Assessment Protocol and Evaluation (SHAPE): a comparative analysis with SMAF and CASH across diverse land uses and management practices

The Soil Management Assessment Framework (SMAF) and the Comprehensive Assessment of Soil Health (CASH) are widely used to assess soil health, but both rely on limited datasets. To address this, the Soil Health Assessment Protocol and Evaluation (SHAPE v1.0) was released in 2024, incorporating expanded datasets and Bayesian modeling to improve soil health interpretation. This study evaluated SHAPE using an independent dataset across diverse land uses (i.e. native forest, pastures and crop fields) with 11 different management practices and compared its performance with SMAF and CASH, while also examining relationships between soil health and soil carbon fractions, including particulate organic carbon (POC) and mineral-associated organic carbon (MAOC). Results showed that SHAPE provided greater sensitivity in distinguishing soil health differences among forests, pastures and croplands than either CASH or SMAF. Overall soil health scores from SHAPE were more closely aligned with CASH than SMAF under Midwestern U.S. conditions, with pasture systems consistently exhibiting the highest soil health. Across all three frameworks, improved soil health was associated with reduced soil disturbance. Organically managed systems also showed greater carbon accumulation throughout the 0–30 cm profile. These findings suggest that integrating carbon fractions with SHAPE may enhance future soil health assessments.