Ensemble pedotransfer functions to derive hydraulic properties for New Zealand soils

Soil Research ◽  
2013 ◽  
Vol 51 (2) ◽  
pp. 94 ◽  
Author(s):  
Rogerio Cichota ◽  
Iris Vogeler ◽  
Val O. Snow ◽  
Trevor H. Webb
Keyword(s):  
New Zealand ◽  
Hydraulic Conductivity ◽  
Water Content ◽  
Hydraulic Properties ◽  
Production Systems ◽  
Clay Content ◽  
Pedotransfer Functions ◽  
Future Research ◽  
Soil Parameters ◽  
Soil Hydraulic

Modelling water and solute transport through soil requires the characterisation of the soil hydraulic functions; however, determining these functions based on measurements is time-consuming and costly. Pedotransfer functions (PTFs), which make use of easily measurable soil properties to predict the hydraulic functions, have been proposed as an alternative to measurements. The better known and more widely used PTFs were developed in the USA or Europe, where large datasets exist. No specific PTFs have been published for New Zealand soils. To address this gap, we evaluated a range of published PTFs against an available dataset comprising a range of different soils from New Zealand and selected the best PTFs to construct an ensemble PTF (ePTF). Assessment (and adjustment when required) of published PTFs was done by comparing measurements and estimates of soil water content and the hydraulic conductivity at selected matric suction values. For each point, the best two or three PTFs were chosen to compose the ePTF, with correcting constants if needed. The outputs of the ePTF are the hydraulic properties at selected matric suctions, akin to obtaining measurements, thus allowing the fit of different equations as well as combining any available measurements. Testing of the ePTF showed promising performance, with reasonably accurate estimates of the water retention of an independent dataset. Root mean square error values averaged 0.06 m3 m–3 for various New Zealand soils, which is within the accuracy level of published PTF studies. The largest errors were found for soils with high clay content, for which the ePTF should be used with care. The performance of the ePTF for estimating soil hydraulic conductivity was not as reliable as for water content, exhibiting large scatter. Predictions of saturated hydraulic conductivity were of the same magnitude as the measurements, whereas the unsaturated values were generally under-predicted. The conductivity data available for this study were limited and highly variable. The estimates for hydraulic conductivity should therefore be used with much care, and future research should address measurements and analysis to improve the predictions. The ePTF was also used to parameterise the SWIM soil module for use in Agricultural Production Systems Simulator (APSIM) simulations. Comparisons of drainage predicted by APSIM against results from lysimeter experiments suggest that the use of the derived ePTF is suited for the estimation of soil parameters for use in modelling. The ePTF is not envisaged as a substitute for measurements but is a useful tool to complement datasets with limited amounts of measured data.

scholarly journals Comparison of the inverse modeling approach and traditional methods to estimate the unsaturated hydraulic properties in a sandy loam soil

2020 ◽  
Vol 34 (3) ◽  
pp. 310-324
Author(s):  
Leonardo Ezequiel Scherger ◽  
Victoria Zanello ◽  
Claudio Lexow
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Hydraulic Properties ◽  
Sandy Loam ◽  
Inverse Solution ◽  
Pedotransfer Functions ◽  
Retention Data ◽  
Soil Water Retention ◽  
Solution Approach ◽  
Soil Hydraulic

The aim of this work is to compare the use of the inverse solution approach in the estimation of soil hydraulic properties with traditional tension disk infiltrometer (TDI) data analysis, field retention data and commonly used pedotransfer functions (PTFs). Field data were collected in an experimental plot located at Bahía Blanca, Argentina. Field infiltration under saturated conditions was measured by the inverse auger hole method and infiltration under unsaturated conditions were carried out with TDI. Field retention data (θ(h)) were also collected periodically. The HYDRUS 2D/3D software was used to optimize soil hydraulic parameters by inverse solution according to TDI data. The saturated hydraulic conductivity measured by inverse auger hole method (5.53 cm.h-1) and calculated by Wooding analytical approach (5.35 cm.h-1) and inverse numerical simulations (5.36 cm.h-1) showed very close values. According to macroporosity estimates infiltrated water is mainly conducted through soils micro and mesopores.  Macropores only channeled 15.9% of total infiltrated flow.  Soil water retention curves (SWRC) predicted by PTFs did not represented correctly field retention data. The best adjustment between water content at specific pressure heads predicted by SWRCs and field measured water content was reached by the TDI inverse solution approach (RMSE: 0.050 cm3.cm-3). The inverse solution approach probed to be a simple and practical method to obtain an accurate estimate of both, SWRC and hydraulic conductivity curve.

euptfv2: updated hydraulic pedotransfer functions for Europe

2021 ◽  
Author(s):  
Brigitta Szabó ◽  
Melanie Weynants ◽  
Tobias Weber
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Properties ◽  
Water Content ◽  
Hydraulic Properties ◽  
Field Capacity ◽  
Pedotransfer Functions ◽  
Predictor Variables ◽  
Soil Hydraulic Properties ◽  
Matric Potential ◽  
Soil Hydraulic

<p>We present improved European hydraulic pedotransfer functions (PTFs) which now use the machine learning algorithm random forest and include prediction uncertainties. The new PTFs (euptfv2) are an update of the previously published euptfv1 (Tóth et al., 2015). With the derived hydraulic PTFs soil hydraulic properties and van Genuchten-Mualem model parameters can be predicted from easily available soil properties. The updated PTFs perform significantly better than euptfv1 and are applicable for 32 predictor variables combinations. The uncertainties reflect uncertainties from the considered input data, predictors and the applied algorithm. The euptfv2 includes transfer functions to compute soil water content at saturation (0 cm matric potential head), field capacity (both -100 and -330 cm matric potential head) and wilting point (-15,000 cm matric potential head), plant available water content computed with field capacity at -100 and -330 cm matric potential head, saturated hydraulic conductivity, and Mualem-van Genuchten parameters of the moisture retention and hydraulic conductivity curves. The influence of predictor variables on predicted soil hydraulic properties is explored and suggestions to best predictor variables given.</p><p>The algorithms have been implemented in a web interface (https://ptfinterface.rissac.hu) and an R package (https://doi.org/10.5281/ZENODO.3759442) to facilitate the use of the PTFs, where the PTFs’ selection is automated based on soil properties available for the predictions and required soil hydraulic property.</p><p>The new PTFs will be applied to derive soil hydraulic properties for field- and catchment- scale hydrological modelling in European case studies of the OPTAIN project (https://www.optain.eu/). Functional evaluation of the PTFs is performed under the iAqueduct research project.</p><p> </p><p>This research has been supported by the Hungarian National Research, Development and Innovation Office (grant no. KH124765), the János Bolyai Research Scholarship of the Hungarian Academy of Sciences (grant no. BO/00088/18/4), and the German Research Foundation (grant no. SFB 1253/12017). OPTAIN is funded by the European Union’s Horizon 2020 Program for research and innovation under Grant Agreement No. 862756.</p>

Hyphal colonization of Rhizophagus irregularis increases unsaturated hydraulic conductivity of a loamy sand distant from roots

2021 ◽  
Author(s):  
Michael Bitterlich ◽  
Richard Pauwels
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Hydraulic Properties ◽  
Volumetric Water Content ◽  
Rhizophagus Irregularis ◽  
Loamy Sand ◽  
Soil Hydraulic Properties ◽  
Unsaturated Hydraulic Conductivity ◽  
Soil Hydraulic ◽  
Root Exclusion

<p>Hydraulic properties of mycorrhizal soils have rarely been reported and difficulties in directly assigning potential effects to hyphae of arbuscular mycorrhizal fungi (AMF) arise from other consequences of AMF being present, i.e. their influence on growth and water consumption rates of their host plants that both also influence soil hydraulic properties.</p><p>We assumed that the typical nylon meshes used for root-exclusion experiments in mycorrhizal research can provide a dynamic hydraulic barrier. It is expected that the uniform pore size of the rigid meshes causes a sudden hydraulic decoupling of the enmeshed inner volume from the surrounding soil as soon as the mesh pores become air-filled. Growing plants below the soil moisture threshold for hydraulic decoupling would minimize plant-size effects on root-exclusion compartments and allow for a more direct assignment of hyphal presence to modulations in soil hydraulic properties.</p><p>We carried out water retention and hydraulic conductivity measurements with two tensiometers introduced in two different heights in a cylindrical compartment (250 cm³) containing a loamy sand, either with or without the introduction of a 20 µm nylon mesh equidistantly between the tensiometers. Introduction of a mesh reduced hydraulic conductivity across the soil volumes by two orders of magnitude from 471 to 6 µm d<sup>-1</sup> at 20% volumetric water content.</p><p>We grew maize plants inoculated or not with Rhizophagus irregularis in the same soil in pots that contained root-exclusion compartments while maintaining 20% volumetric water content. When hyphae were present in the compartments, water potential and unsaturated hydraulic conductivity increased for a given water content compared to compartments free of hyphae. These differences increased with progressive soil drying.</p><p>We conclude that water extractability from soils distant to roots can be facilitated under dry conditions when AMF hyphae are present.</p><p> </p>

scholarly journals Geophysical mapping of soil texture variability in the root zone to improve modelling of the water and nutrient flow.

2020 ◽  
Author(s):  
Kim Schwartz Madsen ◽  
Bo Vangsø Iversen ◽  
Christen Duus Børgesen
Keyword(s):  
Soil Texture ◽  
Hydraulic Properties ◽  
Root Zone ◽  
Clay Fraction ◽  
Clay Content ◽  
Auxiliary Variable ◽  
Pedotransfer Functions ◽  
Soil Hydraulic Properties ◽  
Sampling Density ◽  
Soil Hydraulic

<p>Modelling is often used to acquire information on water and nutrient fluxes within and out of the root zone. The models require detailed information on the spatial variability of soil hydraulic properties derived from soil texture and other soil characteristics using pedotransfer functions (PTFs). Soil texture can vary considerably within a field and is cumbersome and expensive to map in details using traditionally measurements in the laboratory. The electrical conductivity (EC) of the soil have shown to correlate with its textural composition.</p><p>This study investigates the ability of electromagnetic induction (EMI) methods to predict clay content in three soil layers of the root zone. As the clay fraction often is a main predictor in PTFs predicting soil hydraulic properties this parameter is of high interest. EMI and soil textural surveys on four Danish agricultural fields with varying textural composition were used. Sampling density varied between 0.5 and 38 points per hectare. The EMI data was gathered with a Dualem21 instrument with a sampling density 200-3000 points per hectare. The EC values were used together with the measured values of the clay content creating a statistical relationship between the two variables. Co-kriging of the clay content from the textural sampling points with the EC as auxiliary variable produces clay content maps of the fields. Unused (80%) texture points were used for validation. EMI-predicted clay content maps and clay content maps based on the survey were compared. The two sets of soil texture maps are used as predictors for PTF models to predict soil hydraulic properties as input in field-scale root zone modelling.</p><p>The comparisons between EC and clay content show some degree of correlation with an R<sup>2</sup> in the range of 0.55 to 0.80 for the four fields. The field with the highest average clay content showed the best relationship between the two parameters. Co-kriging with EC decreased mean error by 0.016 to 0.52 and RMSE by 0.04 to 1.80 between observed and predicted clay maps.</p>

Prediction of three key hydraulic properties in a soil survey of a small forested catchment

Soil Research ◽  
2002 ◽  
Vol 40 (2) ◽  
pp. 191 ◽  
Author(s):  
D. A. O'Connell ◽  
P. J. Ryan
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Bulk Density ◽  
Hydraulic Properties ◽  
Saturated Hydraulic Conductivity ◽  
Soil Survey ◽  
Coarse Grained ◽  
Pedotransfer Functions ◽  
Explanatory Variables ◽  
Tree Models

Direct measurement of ψ(θ) and K(θ) relationships at all observation sites in soil survey is not feasible. Three key hydraulic properties — water content at field capacity (θ–5 kPa), water content at wilting point (θ–1.5 MPa), and saturated hydraulic conductivity (Ks) — can be used to derive K(θ) and ψ(θ) when combined with bulk density. These properties were measured in 'calibration' horizons in a soil survey in Yambulla State Forest in south-east New South Wales. Pedotransfer functions (PTFs) for predicting θ-5 kPa, θ–1.5 MPa, and Ks from the physical and morphologic soil attributes are presented and evaluated here. Models for predicting θ–5 kPa and θ–1.5 MPa relied on per cent clay. An R2 of 0.64 (for θ–5 kPa) to 0.67 (for θ–1.5 MPa) was obtained for linear regressions using only morphologic explanatory variables. An R2 of 0.73 (for θ–5 kPa) to 0.90 (for θ–1.5 MPa) was obtained if laboratory-measured clay content was included as an explanatory variable. Ks was measured in situ using well permeameters, and used for developing PTFs. Large cores were taken from a small subsample of horizons and measurements of Ks, K–0.1 kPa, K–0.2 kPa, and K–0.5 kPa were made in the laboratory. Ks measurements from well permeameters were similar to K-0.5 kPa from laboratory measurements. Regression and tree models were used to predict Ks. The linear regression had an R2 of 0.55, while the tree models accounted for approximately 40% reduction in deviance. Bulk density was the most useful predictor in all Ks models. The inclusion of per cent rock fragments, bulk density, and estimated percentage clay as useful explanatory variables demonstrated the utility of functional descriptors not routinely measured in soil survey. The models are empirical and were locally calibrated for use in a soil survey. They may be applicable in target domains similar to the source domain (i.e. coarse-grained adamellite soils in similar climatic regimes). surrogates, saturated hydraulic conductivity, K(θ), ψ(θ), Ks, pedotransfer functions, soil survey, soil morphology, PTF.

Estimating soil hydraulic properties from saturation to complete dryness

2021 ◽  
Author(s):  
Budiman Minasny ◽  
Rudiyanto Rudiyanto ◽  
Federico Maggi
Keyword(s):  
Soil Moisture ◽  
Hydraulic Conductivity ◽  
Soil Water ◽  
Hydraulic Properties ◽  
Water Retention ◽  
Pedotransfer Functions ◽  
Soil Hydraulic Properties ◽  
Soil Moisture Dynamics ◽  
Soil Hydraulic ◽  
Moisture Dynamics

<p>To study the effect of drought on soil water dynamics, we need an accurate description of water retention and hydraulic conductivity from saturation to complete dryness. Recent studies have demonstrated the inaccuracy of conventional soil hydraulic models, especially in the dry end. Likewise, current pedotransfer functions (PTFs) for soil hydraulic properties are based on the classical Mualem-van Genuchten functions.</p><p>This study will evaluate models that estimate soil water retention and unsaturated hydraulic conductivity curves in full soil moisture ranges. An example is the Fredlund-Xing scaling model coupled with the hydraulic conductivity model of Wang et al. We will develop pedotransfer functions that can estimate parameters of the model. We will compare it with existing PTFs in predicting water retention and hydraulic conductivity.</p><p>The results show that a new suite of PTFs that used sand, silt, clay, and bulk density can be used successfully to predict water retention and hydraulic conductivity over a range of moisture content. The prediction of hydraulic properties is used in a soil water flow model to simulate soil moisture dynamics under drought. This study demonstrates the importance of accurate hydraulic model prediction for a better description of soil moisture dynamics.</p><p> </p>

scholarly journals Updated European Hydraulic Pedotransfer Functions with Communicated Uncertainties in the Predicted Variables (euptfv2)

2020 ◽  
Author(s):  
Brigitta Szabó ◽  
Melanie Weynants ◽  
Tobias KD Weber
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Pedotransfer Functions ◽  
Model Parameters ◽  
Matric Potential ◽  
Prediction Uncertainty ◽  
Continental Scale ◽  
Available Water ◽  
Plant Available Water ◽  
Soil Hydraulic

Soil hydraulic properties are often derived indirectly, i.e. computed from easily available soil properties with pedotransfer functions (PTFs), when those are needed for catchment, regional or continental scale applications. When predicted soil hydraulic parameters are used for the modelling of the state and flux of water in soils, uncertainty of the computed values can provide more detailed information when drawing conclusions. The aim of this study was to update the previously published European PTFs (Tóth et al., 2015, euptf v1.4.0) by providing prediction uncertainty calculation built into the transfer functions. The new set of algorithms was derived for point predictions of soil water content at saturation (0 cm matric potential head), field capacity (both -100 and -330 cm matric potential head), wilting point (-15.000 cm matric potential head), plant available water, and saturated hydraulic conductivity, as well as the Mualem-van Genuchten model parameters of the moisture retention and hydraulic conductivity curve. The minimum set of input properties for the prediction is soil depth and sand, silt and clay content. The effect of including additional information like soil organic carbon content, bulk density, calcium carbonate content, pH and cation exchange capacity were extensively analysed. The PTFs were derived adopting the random forest method. The advantage of the new PTFs is that they i) provide information about prediction uncertainty, ii) are significantly more accurate than the euptfv1, iii) can be applied for more predictor variable combinations than the euptfv1, 32 instead of 5, and iv) are now also derived for the prediction of water content at -100 cm matric potential head and plant available water content.

scholarly journals Relationship between hydraulic properties and plant coverage of the closed-landfill soils in Piacenza (Po Valley, Italy)

Solid Earth ◽  
2015 ◽  
Vol 6 (3) ◽  
pp. 929-943 ◽  
Author(s):  
C. Cassinari ◽  
P. Manfredi ◽  
L. Giupponi ◽  
M. Trevisan ◽  
C. Piccini
Keyword(s):  
Water Content ◽  
Hydraulic Properties ◽  
Vegetation Type ◽  
Pedotransfer Functions ◽  
Water Retention Curve ◽  
Soil Hydraulic Properties ◽  
Soil Water Retention Curve ◽  
Po Valley ◽  
Plant Coverage ◽  
Soil Hydraulic

Abstract. In this paper the results of a study of soil hydraulic properties and plant coverage of a landfill located in Piacenza (Po Valley, Italy) are presented, together with the attempt to relate the hydraulic properties in relation with plant coverage. The measured soil water retention curve was first compared with the output of pedotransfer functions taken from the literature and then compared with the output of the same pedotransfer functions applied to a reference soil. The landfill plant coverage was also studied. The relationship between soil hydraulic properties and plant coverage showed that the landfill soils have a low water content available for plants. The soils' low water content, together with a lack of depth and a compacted structure, justifies the presence of a nitrophilous, disturbed-soil vegetation type, dominated by ephemeral annual species (therophytes).

scholarly journals Updated European hydraulic pedotransfer functions with communicated uncertainties in the predicted variables (euptfv2)

2021 ◽  
Vol 14 (1) ◽  
pp. 151-175
Author(s):  
Brigitta Szabó ◽  
Melanie Weynants ◽  
Tobias K. D. Weber
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Pedotransfer Functions ◽  
Model Parameters ◽  
Matric Potential ◽  
Prediction Uncertainty ◽  
Continental Scale ◽  
Available Water ◽  
Plant Available Water ◽  
Soil Hydraulic

Abstract. Soil hydraulic properties are often derived indirectly, i.e. computed from easily available soil properties with pedotransfer functions (PTFs), when those are needed for catchment, regional or continental scale applications. When predicted soil hydraulic parameters are used for the modelling of the state and flux of water in soils, uncertainty of the computed values can provide more detailed information when drawing conclusions. The aim of this study was to update the previously published European PTFs (Tóth et al., 2015, euptf v1.4.0) by providing prediction uncertainty calculation built into the transfer functions. The new set of algorithms was derived for point predictions of soil water content at saturation (0 cm matric potential head), field capacity (both −100 and −330 cm matric potential head), wilting point (−15 000 cm matric potential head), plant available water, and saturated hydraulic conductivity, as well as the Mualem–van Genuchten model parameters of the moisture retention and hydraulic conductivity curve. The minimum set of input properties for the prediction is soil depth and sand, silt and clay content. The effect of including additional information like soil organic carbon content, bulk density, calcium carbonate content, pH and cation exchange capacity were extensively analysed. The PTFs were derived adopting the random forest method. The advantage of the new PTFs is that they (i) provide information about prediction uncertainty, (ii) are significantly more accurate than the euptfv1, (iii) can be applied for more predictor variable combinations than the euptfv1, 32 instead of 5, and (iv) are now also derived for the prediction of water content at −100 cm matric potential head and plant available water content. A practical guidance on how to use the derived PTFs is provided.

Pedotransfer functions estimating soil hydraulic properties using different soil parameters

2008 ◽  
Vol 22 (11) ◽  
pp. 1630-1639 ◽  
Author(s):  
Christen D. Børgesen ◽  
Bo V. Iversen ◽  
Ole H. Jacobsen ◽  
Marcel G. Schaap
Keyword(s):  
Hydraulic Properties ◽  
Pedotransfer Functions ◽  
Soil Parameters ◽  
Soil Hydraulic Properties ◽  
Soil Hydraulic
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