Horizon Hydraulic Conductivities Determined in situ for the Wilderness,Mexico and Menfro Soils and Used to Predict Soil Water Content.

摘要

Hydraulic conductivities were determined by in situ methods for the major genetic horizons of three Missouri soils. The interrelationships between hydraulic conductivity,soil matrix potential and soil water content were determined by in situ methods for a fragipan soil of the Wilderness series, a claypan soil of the Mexico series and a deep loess soil of the Mexico series. Hydraulic properties of a draining profile were determined by the instantaneous profile method. Hydraulic properties of a wetting profile were determined by the crust infiltration method for the Mexico and Menfro soils. The hydraulic conductivity values determined by both methods compared favorably when examined at a given matrix potential. Hydraulic conductivities decreased sharply as the soil dried from saturation. The hydraulic conductivity of all horizons in all soils approached a value of 0.01cm/day. This supports the use of a field capacity definition based upon an hydraulic conductivity of 0.01cm/day. The measured hydraulic properties of the Menfro soil were used in a soil-plant-atmosphere model (Saxton, 1974) to predict seasonal soil water content.