Selected Soil Physical Properties and Implications on Water Management System in Northeast Florida

Abstract

Selected soil physical properties at varying depths in a cultivated Alfisol in northeast Florida were studied using classical and geostatistical techniques. The objective was to investigate the variation in the physical properties among and within the sampling depths and understand its implications to field water management in the area. Seventy soil core samples were collected in a grid sampling scheme from five depths: 22.5 cm, 45 cm, 67.5 cm, 90 cm, and 120 cm. Particle size distributions, bulk density (Db), and saturated hydraulic conductivity (Ks) of the soil samples from each depth were measured and statistically compared among depths, and the spatial variation of properties within each sampling depth was determined. Clay content and Db increased significantly with increasing depth, whereas the Ks decreased. The Ks exhibited the maximum variation in both vertical and horizontal direction, whereas Db was the least variable among the three properties. The semivariogram analysis showed a weak spatial autocorrelation in soil properties within the sampling depths. The results suggested that despite significantly low conductivity and high Db of the soil profile at 120 cm, it was not impermeable enough to restrict vertical water movement as opposed to the general perception of the occurrence of a shallow impermeable layer in the profile and consequent perched water table conditions. The results, therefore, provided a definitive insight into the water table management system in the area, which is important for understanding the irrigation system, its efficiency, and consequent water quality impacts on surface and/or groundwater.