Land Management Effects on Near‐Surface Soil Properties of Southeastern U.S. Coastal Plain Kandiudults

Abstract

The National Cooperative Soil Survey is evaluating techniques for better characterization of near‐surface, management‐dependent soil properties associated with soil change (decade to century time scale). The U.S. Soil Taxonomy and soil surveys have been developed with emphasis on subsoil properties to reduce the impacts of management on taxonomic placement. Considering the importance of near‐surface properties on ecosystem function, however, some degree of characterization of these properties is essential. The objectives of this study were to evaluate land use effects on management‐dependent soil properties, C stocks, and soil quality of mature longleaf pine (Pinus palustris Miller) systems relative to more intensively cultivated land use systems in the southeastern U.S. Coastal Plain. Sites in Thomas County, Georgia, representing well‐drained, upland Kandiudults, were selected in each of three land use systems for comparison of near‐surface soil properties. Studied land use systems were mature, multi‐aged longleaf pine forest (LL), slash pine (Pinus elliottii Engelm.) plantation (PP), and conventional row crop (RC) systems. Concentrations of microbial biomass C (0–5 cm) in LL were 69% greater than RC, and LL sequestered 64% more total organic C than RC systems. Inputs of fertilizer were evident in RC (0–30 cm) based on greater exchangeable K (433% greater in LL), base saturation, and extractable P (1700% greater in LL). The soil infiltration rate was 1015% greater in LL than in PP. Principal component analyses indicated that 80% of data variability was explained by exchangeable bases, C pools, and hydraulic soil properties. Clustering suggested that near‐surface soil properties were more similar by land use than by taxonomic‐based soil map units. Land use changed many of the investigated surface soil properties (0–30 cm) at these Coastal Plain sites, resulting in functional and interpretive differences of these soils within similar taxa.