Spatial variation in soil hydraulic properties in an agricultural field estimated using Tension Disc Infiltrometer

Understanding spatial variation in soil hydraulic properties is important for comprehending the physical behaviour of soil and for analysing field-scale water flow and solute transfer processes. Tension disc infiltrometers are commonly used for measuring in-situ unsaturated hydraulic properties of soil. In this study, spatial variation in soil hydraulic properties is analysed for an experimental plot at IIT Kanpur, India after harvest of rice crop using tension disc infiltrometer. Measurements were taken at three different depths of 10, 25 and 50 cm and at multiple locations in the field for consecutive supply pressure heads of -12, -9, -6 and -3 cm. The measured data was analysed using HYDRUS-2D model and four Maulem-van Genutchen parameters (θ_s, α, n and K_s) were inversely estimated. The maximum variation was observed in α at the depth of 50 cm. The reduced variability observed in pore size distribution index (n) could be attributed to the flooded irrigation practice in rice. The findings of this study enhance our understanding of soil-water interaction in agricultural settings.

Keywords: Soil hydraulic properties, Tension disc infiltrometer, HYDRUS-2D