Spatial Variability in Properties Affecting Organic Horizon Carbon Storage in Upland Soils

Citation

Stutter MI, Lumsdon DG, Billett M, Low D & Deeks LK (2009) Spatial Variability in Properties Affecting Organic Horizon Carbon Storage in Upland Soils. Soil Science Society of America Journal, 73 (5), pp. 1724-1732. https://doi.org/10.2136/sssaj2008.0413

Abstract
Quantifying the amount and distribution of soil organic carbon (SOC) within natural soils is important for sample design, C budgeting/pool estimation, and understanding SOC turnover at a process level. We examined the distribution of SOC across a typical UK upland, moorland catchment to establish the amount and spatial structure of variability in key soil properties affecting SOC stocks, namely O horizon C content, bulk density (DB) and horizon depth. Organic horizons of Histosols and Gleysols had greater SOC contents but smaller bulk densities than Podzols and Leptosols. Consequently, SOC density differences between soils were minimized and horizon depth variation became crucial to the measurement of SOC stocks. However, individual Podzol profiles stored appreciable amounts of SOC in O horizons (up to 50 kg m-2). Geostatistical analyses showed spatially structured variance in many properties relating to SOC storage at both plot (variograms reaching sills at ranges 3-8 m) and catchment scales (ranges 437-529 m). The increase in variance from plot to catchment scales was large for O horizon depth. However, DB showed complex scale and soil type inter-relationships, with similar variance at different scales. We show that detailed soil investigations spanning multiple spatial scales are necessary to quantify soil C storage properties for purposes of hydro-ecological modeling and C budgeting at small catchment scales. This has implications for upscaling to regional or national soil C databases.

Journal
Soil Science Society of America Journal: Volume 73, Issue 5