Application of evaporation method to determine the soil water retention curve

Tsvetina Paparkova

Abstract: The evaporation method for determination of the soil water retention curve (SWRC) has been increasingly used as it provides a large number of simultaneous measurements of various soil water contents and matric potentials. The aim of the current study is to use the evaporation method for determination of SWRC via TDR/MUX/mpts apparatus and to compare the results with the data obtained via suction type apparatus. The investigation was carried out on the undisturbed soil samples, taken with rings from Epicalcic Chernozem from flat non-cultivated land in the experimental field Kovachitsa, Montana region and from 6 variants of a field experiment on sloped terrain in the experimental field Trastenik, Ruse region.
Two settings of mini tensiometers in the soil samples were investigated in case of the evaporation method: one vertically inserted mini tensiometer; two horizontally inserted mini tensiometers at two depths. The obtained data for the volumetric soil water content showed good coincidence of the applied methods regarding the mean values at the corresponding matric potentials. The data scattering was relatively high in case of horizontally positions of the mini tensiometers. This can be attributed to a natural variation among the soil samples and to a hysteresis effect or other factors occurring during the laboratory experiment. The later can be overcome by increasing the number of replicates.

Keywords: Epicalcic Chernozem; laboratory mini TDR sensor; mini tensiometer; suction type apparatus

Date published: 2023-04-19