A Simple Method to Assess Key Soil Hydraulic Properties

Abstract

We devised a simple infiltrometer to easily assess soil infiltration capacity and key soil hydraulic properties considering the impact of soil structure on soil infiltration. We conducted two series of five in situ infiltration experiments each on undisturbed forest and grassland soil of contrasting bulk densities and saturated hydraulic conductivity (Ks), and one on six soil columns with mineral soil and various textures without structure. Finally, we measured Ks, saturated water content and the van Genuchten parameters of these soils. Based on the obtained results, we found the best correlations to be exponential correlations between clay content and infiltrated water volume on the one hand and between clay content and the hydraulic properties on the other hand in all cases. Considering the infiltrated volume obtained by the infiltrometer and the measured soil parameters in mineral soil columns as references, we hypothesized that any change in hydraulic parameters of the natural soil is proportional to the change in infiltration volume. Thus, a second term accounting for water volume changes was therefore included in the correlation equations. The first validations of Ks values in forest soil showed good agreement with the laboratory measurements. Further investigations are needed to extend our validation to other soils with various textures.