Toward soil property‐driven identification of peat, limnic, and mineral horizons in Eastern Canada Histosols

Abstract Peat thickness mapping is crucial for supporting soil conservation practices at the field‐scale, but the presence of limnic layers complicates accurate estimates, including through manual probing. At this scale, proximal sensors could provide extensive data on soil stratigraphy. However, this approach relies on a solid understanding of the variability associated with depth and soil materials, including limnic and mineral layers. In Eastern Canada, reference characterization data for all three layers in an agricultural context are limited. Therefore, the objectives of this study were (1) to characterize and compare geophysical properties of peaty, limnic, and mineral layers from drained and cultivated Histosols in Eastern Canada as a function of depth (0–1 m); and (2) to evaluate probes or geophysical sensors that are responsive to properties which may aid in identifying soil layers in situ, minimizing the necessity for manual probing. Ninety sites were sampled across nine fields. At each site, the upper meter of soil was divided into discrete 10 cm layers. The impacts of soil material and depth on six soil properties were assessed using linear mixed‐effects models. Both effects were significant ( p < 0.0001) for all soil properties. Volumetric soil water content, electrical conductivity, and soil penetration resistance were promising candidates for identifying soil materials. In future studies, a time‐domain reflectometry probe could be automated and combined with a soil penetrometer to reduce manual sampling efforts by leveraging regional reference data. Bulk density and organic matter content quantification from this project will support future carbon stock mapping projects.