Soil Water Movement As Affected By Hydraulic Conductivity, Initial Soil Moisture and Irrigation Intensity.

Improving irrigation strategies is of primary importance for conserving water during dry season mainly through avoiding over-irrigation and using available water resources in the most efficient way. The understanding of soil water infiltration behavior, which is affected by hydraulic conductivity, soil water content and water application intensity, in different zones of agricultural production fields is crucial to develop effective field irrigation water management. The objective of this study was to characterize hydraulic conductivity at a farmer’s field and investigate the influence of hydraulic conductivity, initial soil moisture as well as irrigation intensity on soil water flow.

Undisturbed soil cores were collected from ten soil profiles at five depths in a farmer’s field in Princeton, Kentucky for measuring saturated hydraulic conductivity (K_sat). K_sat was measured with a permeameter based on Darcy’s law and used as hydraulic parameter in soil water simulations. Soil water infiltration, redistribution and surface runoff were simulated using HYDRUS-1D under different initial soil moisture and irrigation intensities. Soil wetting front advanced faster with higher initial soil water content. Areas with higher clay content were less permeable and had a higher risk of surface runoff than silt loam locations. Lower irrigation intensity increased water infiltration, facilitated water redistribution and helped to reduce surface runoff. Our results indicated that slow, more frequent, and low-intensity irrigation is recommended for areas with high clay content.

Key words: Infiltration, Saturated hydraulic conductivity, Soil moisture, Irrigation intensity, Surface runoff