17 Jun 2025

Evaluating Permanganate Oxidizable Carbon (POXC)’s Potential for Differentiating Carbon Pools in Wetland Soils

Abstract: Soil carbon (C) storage is a globally important ecosystem service with potential to contribute to climate change mitigation. Wetlands are heavily researched for this. Most studies focus on total C quantification; there is limited methods that evaluate differences in C stability and vulnerability to mineralization within the C pool. Permanganate oxidizable C (POXC) is a well-established soil health indicator shown to be sensitive to changing conditions or management regimes and may prove equally informative. This research quantified POXC in six diverse wetland soils, then evaluated the relationship between POXC and basic soil C properties, microbial indicators, and physical and chemical fractionation metrics. POXC averaged ~ 37 times greater in wetlands than upland agricultural soils, but was less robust in differentiating between individual wetlands than total C or organic matter content. Rather, the ratio of POXC to soil organic C may be a more informative metric for evaluating the proportion of slightly processed C in wetland soils. Significant correlations were found between POXC and almost all soil properties measured, suggesting POXC could be a rapid, reliable, and economical proxy for other analyses. Overall, POXC shows potential for providing novel information about wetland soil C stability, but requires additional research.