scholarly journals Application of k-Nearest code to the improvement of class pedotransfer functions and countrywide Field Capacity and Wilting Point maps

2014 ◽  
Vol 9 (No. 1) ◽  
pp. 1-8 ◽  
Author(s):  
M. Miháliková ◽  
S. Matula ◽  
F. Doležal
Keyword(s):  
Czech Republic ◽  
Soil Water ◽  
Water Retention ◽  
Field Capacity ◽  
Pedotransfer Functions ◽  
Land Resource ◽  
Nearest Neighbour ◽  
Soil Water Retention ◽  
The Czech Republic ◽  
Wilting Point

The database of soil hydrophysical properties in the Czech Republic (HYPRESCZ) which contains the data needed for derivation of pedotransfer functions for soil water retention curves was used for the estimation of field capacity and wilting point of agricultural land resource on a countrywide scale. The results were combined with the existing Soil Texture Map of the Czech Republic to create four new maps, namely the Map of Field Capacity and the Map of Wilting Point for the topsoil and subsoil separately. From the total number of 1048 relevant database entries, only about a half included reliable wilting point data. The k-Nearest computer code employing the k-Nearest neighbour technique was used for estimation of the missing wilting points, which made it possible to use all entries. The estimation uncertainty was assessed in terms of standard deviations and the root mean square error. Finally, two sets of class pedotransfer functions were derived and found sufficiently comparable: (i) the functions estimating the soil water retention curve in the whole range, derived solely from the database entries containing the measured wilting points, and (ii) the functions estimating the field capacity and wilting point only, derived from all database entries, including the k-Nearest neighbour estimated data.

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.

Predicting hydraulic properties of seasonally impounded soils

2009 ◽  
Vol 148 (2) ◽  
pp. 159-170 ◽  
Author(s):  
N. G. PATIL ◽  
G. S. RAJPUT ◽  
R. K. NEMA ◽  
R. B. SINGH
Keyword(s):  
Hydraulic Properties ◽  
Water Retention ◽  
Monsoon Season ◽  
Field Capacity ◽  
Pedotransfer Functions ◽  
Agricultural Crop ◽  
Statistical Regression ◽  
Soil Water Retention ◽  
Retention Characteristics ◽  
Wilting Point

SUMMARYAgricultural crop management decisions often require data on hydraulic properties of soils. Little information is available on hydraulic properties of clay soils that are impounded by rainwater (known as ‘Haveli’ lands) every year during the monsoon season in large tracts of Madhya Pradesh in India. Estimating hydraulic properties using global pedotransfer functions (PTFs) is one possible way to collect such information. Rules in the widely used global PTF Rosetta were executed to obtain estimates of two important hydraulic properties, namely soil water retention characteristics (SWRC) and saturated hydraulic conductivity (Ks). SWRC estimates obtained with maximum input (particle size distribution, bulk density, field capacity and permanent wilting point) in Rosetta were relatively closer to the laboratory-measured data as compared with the estimates obtained with lower levels of input. Root mean square error (RMSE) of estimates ranged from 0·01 to 0·05 m3/m3. Hierarchical PTFs to predictKsfrom basic soil properties were derived using statistical regression and artificial neural networks. Evaluation of these indicated that neural PTFs were acceptable and hence could be used without loss of accuracy.

scholarly journals Using of pedotransfer functions for assessment of hydrolimits

2011 ◽  
Vol 48 (No. 9) ◽  
pp. 407-412 ◽  
Author(s):  
V. Štekauerová ◽  
J. Skalová ◽  
J. Šútor
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
Region Of Interest ◽  
Calcium Content ◽  
Field Capacity ◽  
Pedotransfer Functions ◽  
Water Retention Curve ◽  
Soil Water Retention ◽  
Laboratory Assessment ◽  
Retention Curve

Soil hydrologic coefficients, also called hydrolimits, are soil water contents defined for certain values of water potentials. Closer attention is paid to three hydrolimits: field capacity, point of decreased availability, and wilting point. The hydrolimits can be found by various ways. Their assessment under natural conditions should be seen as laboratory assessment of hydrolimit values or use of soil water retention curves for reading of hydrolimits. Therefore, some methods for indirect assessment of the water retention curve from actually mapped soil characteristics such as soil texture, bulk density and calcium content were devised. They are generally called pedotransfer functions (PTFs). Aim of the study is to calculate values of some important hydrolimits using PTFs. The hydrolimits calculated by this way are compared to hydrolimits determined from another measured water retention curves. The presented study documents an efficiency and promptness of PTFs use for a&nbsp;region of interest for dynamics evaluation of water storage in the soil aeration zone considering the water supply of plants.

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.

Multiscale Pedotransfer Functions for Soil Water Retention

2007 ◽  
Vol 6 (4) ◽  
pp. 868-878 ◽  
Author(s):  
Raghavendra B. Jana ◽  
Binayak P. Mohanty ◽  
Everett P. Springer
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
Pedotransfer Functions ◽  
Soil Water Retention

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 HYPRESCZ - database of soil hydrophysical properties in the Czech Republic

2013 ◽  
Vol 8 (No. 1) ◽  
pp. 34-41 ◽  
Author(s):  
M. Miháliková ◽  
S. Matula ◽  
F. Doležal
Keyword(s):  
Czech Republic ◽  
Mean Squared Error ◽  
Arable Land ◽  
Pedotransfer Functions ◽  
Coefficient Of Determination ◽  
Quality Of Data ◽  
Soil Water Retention ◽  
The Czech Republic ◽  
European Database ◽  
S Model

The database of soil hydrophysical properties in the Czech Republic called HYPRESCZ was created. It is based on the European database HYPRES, HYdraulic PRoperties of European Soils, and follows its structure with few modifications. It collects the available data from the Czech Republic from which pedotransfer functions (PTFs) for the estimation of soil hydrophysical properties from easily available soil properties can be derived and 2101&nbsp;database entries were collected. The entries have different quality of data, out of the total number of entries 707 entries were applicable to PTFs derivation for the estimation of soil water retention curves (SWRCs). After elimination of replicates, finally 159 unique soil horizons (arable land only) were used for PTFs derivation. The parametric continuous pedotransfer functions for estimation of SWRCs in the Czech Republic were derived within this study and are based on W&ouml;sten&rsquo;s model. The retention curves were estimated using both these newly derived PTFs and W&ouml;sten&rsquo;s original model, which was derived for European soils in general. The uncertainty of estimation was evaluated, employing the root mean squared error (RMSE) and the coefficient of determination (R<sup>2</sup>) comparing the PTF-estimated and the directly fitted retention curves. The reliability of the newly derived PTFs for Czech soils was higher (RMSE = 0.059 cm<sup>3</sup>/cm<sup>3</sup> and R<sup>2</sup> = 71%) compared to W&ouml;sten&rsquo;s general PTFs (RMSE = 0.11 cm<sup>3</sup>/cm<sup>3</sup> and R<sup>2</sup> = 36%).

Soil Water Retention Characteristics of Black Soils of India and Pedotransfer Functions Using Different Approaches

2013 ◽  
Vol 139 (4) ◽  
pp. 313-324 ◽  
Author(s):  
N. G. Patil ◽  
P. Tiwary ◽  
D. K. Pal ◽  
T. Bhattacharyya ◽  
Dipak Sarkar ◽  
...  
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
Pedotransfer Functions ◽  
Soil Water Retention ◽  
Retention Characteristics

Uncertainty analysis for large-scale prediction of the van Genuchten soil-water retention parameters with pedotransfer functions

Soil Research ◽  
2014 ◽  
Vol 52 (5) ◽  
pp. 431 ◽  
Author(s):  
K. Liao ◽  
S. Xu ◽  
J. Wu ◽  
Q. Zhu
Keyword(s):  
Soil Properties ◽  
Soil Water ◽  
Water Retention ◽  
Pedotransfer Functions ◽  
Soil Water Retention ◽  
Input Uncertainty ◽  
Spatial Estimation ◽  
Uncertainty Measurement ◽  
Error Bars ◽  
Retention Parameters

Hydrological, environmental and ecological modellers require van Genuchten soil-water retention parameters that are difficult to measure. Pedotransfer functions (PTFs) are thus routinely applied to predict hydraulic parameters (θs, ln(α) and n) from basic soil properties (e.g. bulk density, soil texture and organic matter content). This study investigated the spatial variations of van Genuchten parameters via geostatistical methods (e.g. kriging and co-kriging with remote-sensing data) and multiple-stepwise-regression-based PTFs with a limited number of samples (58) collected in Pingdu City, Shandong Province, China. The uncertainties in the spatial estimation of van Genuchten parameters were evaluated using bootstrap and Latin hypercube sampling methods. Results show that PTF-estimated parameters are less varied than observed parameters. The uncertainty in the parameter estimation is mainly due to the limited number of samples used for deriving PTFs (intrinsic uncertainty) and spatial interpolations of basic soil properties by (co)kriging (input uncertainty). When considering the intrinsic uncertainty, 36%, 29% and 47% of measurements are within the corresponding error bars (95% confidence intervals of the predictions) for the θs, ln(α) and n, respectively. When considering both intrinsic and input uncertainties, 86%, 66% and 88% of observations are within the corresponding error bars for the θs, ln(α) and n, respectively. Therefore, the input uncertainty is more important in the spatial estimation of van Genuchten parameters than the intrinsic uncertainty. Measurement of basic soil properties at high resolution and properly use of powerful spatial interpolation approach are both critical in the accurate spatial estimation of van Genuchten parameters.

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