Spatial and fractal characterization of soil hydraulic properties along a catena

Abstract

AbstractSoil hydraulic properties influence water and nutrient availability as well as environmental sustainability, and these properties vary across several landscape positions. This study investigated the spatial variability and fractal characterization of soil hydraulic properties across five slope positions: summit, shoulder, back, foot, and toe slopes. Triplicate soil samples (0–18 cm) were collected from each slope position from a pasture field planted to tall fescue [Festuca arundinacea Schreb., syn. schendonorus arundinaceus (Schreb.) Dumort., nom. cons.]. Soil bulk density (ρb); saturated hydraulic conductivity (Ksat); water retention at 0, −33, and −1,500 kPa soil water matric potentials; soil organic carbon (SOC); and various pore sizes (macropores [>1,000 μm], mesopores [10–1,000 μm], and micropores [<10 μm]) were analyzed. Results show that SOC was 26% higher, while ρb was 10% lower at the toe slope compared with the summit. Similarly, Ksat values were 3, 9, 16, and 2% greater at the toe slope compared with the summit, shoulder, back, and foot slopes, respectively. Semivariogram analysis showed that the gaussian isotropic model provided the best fit (R2 > .99) for hydraulic properties across all slope positions. The range of spatial variability of soil hydraulic properties was between 5.60 and 123.00 m at all slope positions. The fractal dimensions of soil hydraulic properties across all slope positions ranged from 0.784 to 1.966. Soil hydraulic properties were similar at the foot and toe slopes, which might favor improved crop productivity at these slope positions.