Evaluating Measures to Assess Soil Health in Long‐Term Agroecosystem Trials

Summary

This evaluation of soil health metrics across diverse long-term agroecosystem experiments in the Pacific Northwest proposes a seven-criterion framework for assessing soil monitoring tools. The authors found that measures of active soil organic matter were highly variable and insensitive to management practices, whereas permanganate oxidizable carbon demonstrated sensitivity to stabilized soil organic matter and strong correlation with more recalcitrant carbon and nitrogen pools, making it the highest-scoring metric for soil health assessment within the region.

UK applicability

The framework and evaluation criteria proposed may be applicable to UK soil health assessment programmes, though regional validation would be necessary given differences in soil types, climate, and management intensity between the Pacific Northwest and the United Kingdom. The finding that POXC is superior to active carbon measures could inform UK soil health monitoring protocols, particularly for long-term agroecological transition assessment.

Key measures

Soil organic carbon (SOC), total nitrogen, acid nonhydrolyzable carbon and nitrogen, acid-hydrolyzable carbon and nitrogen, microbial biomass carbon and nitrogen, carbon mineralization, permanganate oxidizable carbon (POXC), ion exchange membrane nitrogen, potential nitrogen mineralization, and the Haney soil health index

Outcomes reported

The study evaluated multiple soil organic matter (SOM) properties across five long-term field experiments (2–30 years old) in the inland Pacific Northwest to assess their effectiveness as soil health metrics. Permanganate oxidizable carbon (POXC) was identified as the most effective metric based on seven evaluation criteria: evidence-based, sensitivity to change, logistical feasibility, cost-effectiveness, accuracy and precision, in situ performance, and management utility.

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