Water table dynamics across an Aquod-Udult transition in Florida flatwoods

Spodosol formation in the coastal plain of the southeastern United States i s largely restricted to areas where there are fluctuating water table condi tions within the zone of podzolization. The purpose of this study was to do cument specific hydrologic conditions associated with podzolization, and to address the idea that frequency and duration of saturation are critical th reshold factors triggering and driving the process regionally. The study wa s conducted along an abrupt Aquod-to-Udult transition, which showed the com monly observed trend of an upward curving spodic horizon (Bh) that merges w ith the A horizon of the Udult, Objectives were to (i) compare the Aquod an d the Udult with respect to depth and duration of saturation and (ii) deter mine hydraulic responses of horizons to rainfall events along the Aquod-Udu lt transition, Water table fluctuations within a rectangular area (15 X 25 m) encompassing the soils were monitored, using piezometers, over a 1-year period. Hydraulic and horizon surfaces were interpolated by Kriging. Result s confirmed that the water table sloped sharply downward across the Aquod-t o-Udult transition during most of the sampling period but was nearly level for brief periods after heavy rains. The hydraulic response of the Udult ar gillic horizon to rain events was much slower than that of the Aquod argill ic horizon, such that the Udult periodically experienced epiaquic condition s. The hydraulic head of the Aquod argillic horizon was consistently higher than that of the Udult argillic horizon; discharge from the Aquod argillic compensated for evapotranspiration and maintained wetter conditions in the upper sandy horizons. Depth and color development of the Aquod Bh horizon were inversely related to water table depth along the transition. Hence, th ese factors are not simple functions of central tendencies in water table d ynamics but relate to duration of saturated conditions in the near-surface sandy zone.