Parameterization of the instantaneous profile method to determine soil hydraulic conductivity in evaporation experiments

Soil hydraulic conductivity is an essential property and its quantification is essential for any study that involves soil water movement. Methods of determination based on internal drainage, such as the instantaneous profile method (IPM) are among the most commonly used, but their determination is restricted to the soil water range between saturation and field capacity. In order to obtain hydraulic conductivity for lower water contents, we propose an IPM that takes into account evaporation as well as a calculation routines to determine the zero flux depth and to estimate flux densities. The application of the method is demonstrated by obtaining results for hydraulic conductivity of the surface layer of a monitored profile in a 12-day field experiment. The estimated maximum zero flux depth was about 0.50 m. Soil water content varied from 0.25 to 0.21 m(3) m(-3), complementing the range obtained in experiments without evaporation at the same site. Results confirm the applicability of the method, which is especially useful to extend the range of soil water contents in the surface layer obtained in this kind of experiment.