Soil hydraulic conductivities and their spatial and temporal variations in a vertisol uri icon

abstract

  • Knowledge of soil hydraulic parameters and their spatiotemporal variation is crucial for estimating the water and solute fluxes across the landatmosphere boundary and within the vadose zone at different scales. The objective of this study was to determine soil hydraulic conductivities [saturated hydraulic conductivity, Ksat, and unsaturated hydraulic conductivity, K()] and their spatial and temporal variations in a claydominated biporous Vertisol near College Station, TX, using tension infiltrometers. The study was conducted within a 20 by 16m plot across several seasons during a 21mo period (May 2003January 2005) to investigate the impact of varying disk sizes (measurement support) on K(), and the spatial and temporal variations of K() under natural environmental conditions due to pore space evolution. Infiltration occurred in a bimodal fashion consisting of preferential flow (occurring at soil water pressure heads [] = 0.05 to 0 m) and matrix flow (at = 0.2 to 0.1 m). Biological and structural macropores present in the soil resulted in gravitydominated flow near saturation ( = 0.05 to 0 m) for all experiments. The Student's ttest of analysis of variance indicated that hydraulic conductivities were not affected by changes in the infiltration disk sizes. Although the K() values at four different locations within the plot did not show significant spatial variability, they demonstrated strong temporal variation during the 21mo period based on the evolution of natural environmental conditions due to seasonal precipitation, root growth and decay, and structural pore space dynamics. Temporal trends of K() indicated that hydraulic conductivities close to saturation were positively correlated with antecedent moisture conditions reflecting liquid cohesion, water films bridging across cracking peds, and the activation of flow in biological and structural macroporosity in the biporous soil system.

published proceedings

  • SOIL SCIENCE SOCIETY OF AMERICA JOURNAL

author list (cited authors)

  • Das Gupta, S., Mohanty, B. P., & Koehne, J. M.

complete list of authors

  • Das Gupta, Surajit||Mohanty, Binayak P||Koehne, J Maximilian

publisher