Spatial Variability of Morphological Properties at a Florida Flatwoods Site

Abstract Soil profiles were described on a grid at 60‐m intervals to assess the variability of soil morphological properties in 60 ha of Florida flatwoods. Depths from the soil surface to the spodic and argillic horizons were mapped using field data supplemented with kriged values. In addition, a 120 by 120 m subarea was described at 15‐m intervals. The occurrence of a single deep spodic horizon at a few peripheral locations influenced the structure of variograms and contributed to anisotropy. The soil profiles adjacent to these locations exhibited two spodic horizons, one much deeper than the other. The variance structure model for spodic horizon depth in the overall 60‐ha site accurately described the variance structure for the subarea. At some sampling locations, neither a spodic nor an argillic horizon was observed. Absence of the argillic horizon was more common than absence of the spodic horizon. Areal discontinuity in the argillic horizon was more extensive than in the spodic horizon. Such discontinuity in the argillic horizon was observed near and between depressional areas. Although the variance structure of depth to the argillic horizon could be described using an anisotropic variogram model, better estimates of depth to the argillic horizon were obtained using variograms of residuals and drift functions.