scholarly journals Pedotransfer functions of soil water properties to estimate the S-index

2018 ◽  
Vol 22 (7) ◽  
pp. 465-470
Author(s):  
João H. Caviglione
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
Field Conditions ◽  
Pedotransfer Functions ◽  
Water Retention Curve ◽  
Coefficient Of Determination ◽  
Native Forest ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Soil Physical Quality

ABSTRACT One big challenge for soil science is to translate existing data into data that is needed. Pedotransfer functions have been proposed for this purpose and they can be point or parametric when estimating the water retention characteristics. Many indicators of soil physical quality have been proposed, including the S-Index proposed by Dexter. The objective of this study was to assess the use of pedotransfer functions for soil water retention to estimate the S-index under field conditions in the diversity of soils of the Paraná state. Soil samples were collected from 36 sites with textures ranging from sandy to heavy clay in the layers of 0-0.10 and 0.10-0.20 m and under two conditions (native forest and cultivated soil). Water content at six matric potentials, bulk density and contents of clay, sand and silt were determined. Soil-water retention curve was fitted by the van Genuchten-Mualem model and the S-index was calculated. S-index was estimated from water retention curves obtained by the pedotransfer function of Tomasella (point and parametric). Although the coefficient of determination varied from 0.759 to 0.895, modeling efficiency was negative and the regression coefficient between observed and predicted data was different from 1 in all comparisons. Under field conditions in the soil diversity of the Paraná state, restrictions were found in S-index estimation using the evaluated pedotransfer functions.

scholarly journals Assessment of pedotransfer functions for estimating soil water retention curves for the amazon region

2014 ◽  
Vol 38 (3) ◽  
pp. 730-743 ◽  
Author(s):  
João Carlos Medeiros ◽  
Miguel Cooper ◽  
Jaqueline Dalla Rosa ◽  
Michel Grimaldi ◽  
Yves Coquet
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
Soil Layer ◽  
Direct Determination ◽  
Exchange Capacity ◽  
Pedotransfer Functions ◽  
Water Retention Curve ◽  
Spatial And Temporal Variability ◽  
Soil Water Retention Curve ◽  
Soil Water Retention

Knowledge of the soil water retention curve (SWRC) is essential for understanding and modeling hydraulic processes in the soil. However, direct determination of the SWRC is time consuming and costly. In addition, it requires a large number of samples, due to the high spatial and temporal variability of soil hydraulic properties. An alternative is the use of models, called pedotransfer functions (PTFs), which estimate the SWRC from easy-to-measure properties. The aim of this paper was to test the accuracy of 16 point or parametric PTFs reported in the literature on different soils from the south and southeast of the State of Pará, Brazil. The PTFs tested were proposed by Pidgeon (1972), Lal (1979), Aina & Periaswamy (1985), Arruda et al. (1987), Dijkerman (1988), Vereecken et al. (1989), Batjes (1996), van den Berg et al. (1997), Tomasella et al. (2000), Hodnett & Tomasella (2002), Oliveira et al. (2002), and Barros (2010). We used a database that includes soil texture (sand, silt, and clay), bulk density, soil organic carbon, soil pH, cation exchange capacity, and the SWRC. Most of the PTFs tested did not show good performance in estimating the SWRC. The parametric PTFs, however, performed better than the point PTFs in assessing the SWRC in the tested region. Among the parametric PTFs, those proposed by Tomasella et al. (2000) achieved the best accuracy in estimating the empirical parameters of the van Genuchten (1980) model, especially when tested in the top soil layer.

Evaluation of soil texture data for estimating soil water retention curve

2009 ◽  
Vol 89 (4) ◽  
pp. 461-471 ◽  
Author(s):  
B Ghanbarian-Alavijeh ◽  
A M Liaghat
Keyword(s):  
Soil Water ◽  
Soil Texture ◽  
Water Retention ◽  
Geometric Mean ◽  
Pedotransfer Functions ◽  
Water Retention Curve ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Statistical Parameters ◽  
Retention Curve

The soil water retention curve (SWRC) is one of the basic characteristics used in determining soil hydraulic properties, including unsaturated hydraulic conductivity. As its measurement is time consuming and difficult, much effort has been expended to develop indirect methods, such as pedotransfer functions and empirical relationships, to estimate SWRC. In this study, three methods were evaluated based on estimation of retention models parameters and, consequently, the soil water retention curve. For this purpose, soil data collected from three data bases, totaling 72 soil samples with 11 different textures, were used in this study. The statistical parameters such as: MR (mean of residual), RE (relative error), RMSE (root mean square error), AIC (Akaike’s information criterion) and GMER (geometric mean error ratio) showed that the Saxton et al. (1986) method estimates the soil water retention curve better than the other methods.Key words: Pedotransfer function, soil texture, soil water retention curve

scholarly journals Developing Pseudo Continuous Pedotransfer Functions for International Soils Measured with the Evaporation Method and the HYPROP System: I. The Soil Water Retention Curve

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3425
Author(s):  
Amninder Singh ◽  
Amir Haghverdi ◽  
Hasan Sabri Öztürk ◽  
Wolfgang Durner
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
Soil Samples ◽  
Pedotransfer Functions ◽  
Water Retention Curve ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Data Set ◽  
Retention Curve ◽  
Evaporation Method

Direct measurements of soil hydraulic properties are time-consuming, challenging, and often expensive. Therefore, their indirect estimation via pedotransfer functions (PTFs) based on easily collected properties like soil texture, bulk density, and organic matter content is desirable. This study was carried out to assess the accuracy of the pseudo continuous neural network PTF (PCNN-PTF) approach for estimating the soil water retention curve of 153 international soils (a total of 12,654 measured water retention pairs) measured via the evaporation method. In addition, an independent data set from Turkey (79 soil samples with 7729 measured data pairs) was used to evaluate the reliability of the PCNN-PTF. The best PCNN-PTF showed high accuracy (root mean square error (RMSE) = 0.043 cm3 cm−3) and reliability (RMSE = 0.061 cm3 cm−3). When Turkish soil samples were incorporated into the training data set, the performance of the PCNN-PTF was enhanced by 33%. Therefore, to further improve the performance of the PCNN-PTF for new regions, we recommend the incorporation of local soils, when available, into the international data sets and developing new sets of PCNN-PTFs.

scholarly journals Comparison Of Selected Pedotransfer Functions For The Determination Of Soil Water Retention Curves

2015 ◽  
Vol 23 (3) ◽  
pp. 33-36 ◽  
Author(s):  
Michal Kupec ◽  
Peter Stradiot ◽  
Štefan Rehák
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
Pedotransfer Functions ◽  
Water Retention Curve ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Undisturbed Soil ◽  
Retention Curve ◽  
Van Genuchten Model

Abstract Soil water retention curves were measured using a sandbox and the pressure plate extractor method on undisturbed soil samples from the Borská Lowland. The basic soil properties (e.g. soil texture, dry bulk density) of the samples were determined. The soil water retention curve was described using the van Genuchten model (Van Genuchten, 1980). The parameters of the model were obtained using the RETC program (Van Genuchten et al., 1991). For the determination of the soil water retention curve parameters, two pedotransfer functions (PTF) were also used that were derived for this area by Skalová (2003) and the Rosetta computer program (Schaap et al., 2001). The performance of the PTFs was characterized using the mean difference and root mean square error.

scholarly journals Estimation of the soil water retention curve (SWRC) using pedotransfer functions (PTFs)

2008 ◽  
Vol 2 (No. 4) ◽  
pp. 113-122 ◽  
Author(s):  
S. Matula ◽  
M. Mojrová ◽  
K. Špongrová
Keyword(s):  
Czech Republic ◽  
Soil Water ◽  
Water Retention ◽  
Pedotransfer Functions ◽  
Water Retention Curve ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
The Czech Republic ◽  
Retention Curve ◽  
Parameter Fitting

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.

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