Taxonomic and Geographic Distribution of Soil Organic Carbon Pools in Ohio

Abstract

Spatial distribution information about soil organic C (SOC) pools at a proper scale is critical for developing feasible C sequestration programs. This study characterizes the spatial variation in SOC pools related to soil taxon, Major Land Resource Area (MLRA), and land use. Grouping data by the land uses associated with soil orders within each MLRA leads to a statewide average SOC pool of 10.2 ± 2.8 kg m −2 in the upper 1‐m depth, ranging from 7.1 kg m −2 in Ultisols to 117 in Histosols (8.8, 11.3, 12.7, and 16.9 kg m −2 in Alfisols, Inceptisols, Entisols, and Mollisols, respectively), and geographically varying from 7.7 kg m −2 in MLRA 124 to 12.0 in both MLRA 99 and 111. These variations can be also partially attributed to the properties for suborder differentiation. Moreover, land use effects are confounded by preferential selection of land for cropland use and site topographic features, resulting in a higher SOC pool in cropland (10.9 kg m −2 ) than in both forestland (9.5 kg m −2 ) and pastureland (8.4 kg m −2 ). The grand total SOC storage in Ohio ranges from 853 to 881 Tg (1 Tg = 10 12 g). The SOC pool is primarily related to landscape slope and soil drainage, and must be considered in interpretations for C sequestration potential among land uses for each soil taxon at the MLRA scale.