Abstract
Hydraulic conductivity at and near saturation (Ks and K(h)) are among the most important characteristics defining water behavior in soil. Characterization of possibilities, advantages and limitations of the Mini Disk infiltrometer (MDI) for Ks and K(h) determination in comparison with Hood infiltrometer (HI) was the main aim of this study. The MDI device was subjected to testing on a cultivated silty clay loam soil under three different tillage treatments; conventional, reduced and no-tillage plot. The results are based on 72 infiltration experiments carried out during four experimental phases within one year. Steady-state and transient data analysis methods were applied. K(h) values were determined for van Genuchten hydraulic parameters taken from different sources (two versions of User’s manual, Rosetta). The results show suitability of MDI to determine K(h) of tested soil; clear differences have been observed between the K(h) values measured on plots with different tillage treatment. However, these values were significantly lower (ANOVA, α = 0.05) than those measured by HI. MDI based data were reflecting seasonal changes in structure and pore-size distribution with quantification of macropore contribution to the total saturated flux. Application of K(h) MDI data for fine-textured and structural soils evaluated before 2010 should be reconsidered.
Highlights
Hydraulic conductivity characterizes the ability of soil to infiltrate and transport water through the soil profile; saturated hydraulic conductivity Ks for the saturated soil and unsaturated hydraulic conductivity K(h) for the unsaturated soil
The inverse solution provides a numerical solution of the Richards equation for given initial and boundary conditions, which are specified within the input data
The results are in agreement with findings of Çelik et al [26], who investigated possible differences in physical properties of soils under different tillage treatments for 10 years
Summary
Hydraulic conductivity characterizes the ability of soil to infiltrate and transport water through the soil profile; saturated hydraulic conductivity Ks for the saturated soil and unsaturated hydraulic conductivity K(h) for the unsaturated soil. The amount of conducted water is determined by the size and volumetric proportion of the pores, and their geometric configuration given by their connectivity and tortuosity. These characteristics in a cultivated soil are subjected to changes in relation to the vegetation season and applied agrology, such as soil tillage treatment. The hydraulic conductivity is a key parameter in practically all models dealing with water resources, environmental and health risk, soil erosion assessment, etc. In situ techniques can produce more representative values of hydraulic conductivity in comparison to laboratory measurements on soil core samples, as they characterize larger volume of soil in its natural state with the undisturbed pore network [1,2,3]
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