Abstract
Soil hydraulic characteristics, especially the soil water retention curve and hydraulic conductivity, are essential for many agricultural, environmental, and engineering applications. Their measurement is time-consuming and thus costly. Hence, many researchers focused on methods enabling their indirect estimation. In this paper, W&ouml;sten&rsquo;s continuous pedotransfer functions were applied to the data from a selected locality in the Czech Republic, Ti&scaron;ice. The available data set related to this locality consists of 140 measured soil water retention curves, and the information about the soil texture, bulk density &rho;<sub>d</sub>, and organic matter content determined at the same time. Own continuous pedotransfer functions were derived, following the methodology used in continuous pedotransfer functions. Two types of fitting, 4-parameters and 3-parameters, were tested. In 4-parameter fitting, all parameters of the van Genuchten&rsquo;s equation, &theta;<sub>s</sub>, &theta;<sub>r</sub>, &alpha;, n, were optimized; in 3-parameter fitting, only three parameters, &theta;<sub>r</sub>, &alpha;, n, were optimised while the measured value of &theta;<sub>s</sub> was set as constant. Based on the results, it can be concluded that the general equations of W&ouml;sten&rsquo;s pedotransfer functions are not very suitable to estimate the soil water retention curves for the locality Ti&scaron;ice in the Czech Republic. However, the parameters of the same W&ouml;sten&rsquo;s equations, which were calculated only from the data for each particular locality, performed much better. The estimates can be improved if the value for the saturated soil water content &theta;<sub>s</sub> is known, applied and not optimised (the case of 3-parameter fitting). It can be advantageous to estimate SWRC for a locality with no data available, using PTFs and the available basic soil properties. In addition, to measure some retention curves and/or some their parameters, like &theta;<sub>s</sub>, can improve the accuracy of the SWRC estimation.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have