Using Ground‐penetrating Radar to Study Changes in Soil Map Unit Composition in Selected Histosols

Intensive cultivation practices and subsidence of Histosols in Florida's Everglades Agricultural Area (EAA) has resulted in the need to reevaluate soils information gathered and published in the early 1970s as part of the National Cooperative Soil Survey Program. This study was initiated to determine the present range, thickness, distribution, and spatial variability of selected Histosol map units in the EAA using ground‐penetrating radar (GPR). Four consociations were selected for study. The thickness of the organic materials has decreased significantly when compared to the thickness in the published soil survey report. When compared with the GPR data, the proportions of areas mapped in the 1970s that have thick organic layers (>90 cm) had decreased with a corresponding increase of areas with thin organic layers (<90 cm). This shift represents approximately a 35% increase in lithic subgroups. Also, many areas previously mapped as consociations need to be recorrelated as complexes; only the Okeechobee muck map unit would remain a discrete consociation. Using the GPR increased sampling speed and enabled a continuous profile of organic thickness over bedrock to be obtained.