Saturday, 15 July 2006

Estimation of the Soil Moisture Retention Curve (SMRC) using Pedotransfer Functions (PTF).

Svatopluk Matula and Kamila Spongrova. Czech University of Agriculture in Prague, Dept. of Soil Science and Geology, Kamycka 129, Prague, CZ-165 21, Czech Republic

Soil hydraulic properties are needed as input data to describe and simulate transport of water and solutes in the soil profile. The most important characteristics are the soil moisture retention curve (SMRC) (h) and hydraulic conductivity. SMRC represents the amount of water remaining in the soil under equilibrium conditions and is unique for each soil. The measurement of the SMRC is labours and time consuming and sometimes there are not enough data available. The SMRC estimation models have been used extensively. More available soil properties, such as particle size distribution, organic matter content, soil structure and bulk density, have been taken into the calculations. Bouma, 1989 called these models pedotransfer functions. This preliminary study is based on the following European works: Wösten et al., 1998, Wösten et al., 1999 and others. Pedotransfer functions derived by Wösten et al., 1998 were used in the first part of the study. In the second part own pedotransfer functions were derived for localities with available data. The methodology of data processing was the same as used in Wösten et al., 1998 for continuous pedotransfer functions. Continuous pedotransfer functions were tested on the data sets from the following localities in the Czech Republic: Cerhovice, Černičí, Brozany, Ovesná Lhota, Tupadly, Džbánov, Podlesí, Žichlínek. Unfortunately, the data sets were not as large as the data sets in Wösten's work. Such large data sets are not available to the authors in the CR. Therefore only these data were used as an input for this preliminary study. Some examples of a rather good estimate of SMRC (expressed as pF curves) were found for example for the locality Cerhovice and Černičí, less successful are the estimates for Brozany and in the localities Ovesná Lhota, Tupadly and Džbánov, Podlesí, Žichlínek, the estimates were not successful due to the lack of input data. The applications of continuous pedotransfer functions derived by Wösten, 1998 on the soils tested were not successful. Key words: soil moisture retention curve, multiple linear regressions, pedotransfer functions.

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