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A grid sampling pattern of 108 sample locations at distances ranging from 15 to 122 m was used to develop a baseline characterization of soil physical and hydrological properties in a 40 ha field. Statistical distributions of silt and sand were not normal. Coefficients of variation of sand, silt and clay contents were 59%, 18% and 25%. Pedotransfer functions (PTFs) were developed using indicator...
The determination of water retention characteristics of soils in tropical regions is hampered by the lack of adequate laboratory equipment and high cost of analysis. In this paper the possibilities of estimating water retention characteristics from routinely determined properties of Ferralsols/Oxisols and related soils are investigated. Two sets of data on soils from South America, Africa and South...
This paper deals with the applicability and validation of three predictive models for the estimation of soil hydraulic parameters (soil water characteristic and unsaturated hydraulic conductivity) by using routinely available soil data. Comparisons were made of the models of Campbell [Campbell, G.S., 1974. A simple model for determining unsaturated conductivity from moisture retention data. Soil Sci...
This paper presents pedotransfer functions to estimate soil water retention parameters of the Hutson-Cass modified form of the Brooks-Corey equation from soil texture, bulk density and organic carbon content. Multiple regression equations are developed from a subset (286 soil horizons) of the soil physical properties database of England and Wales. For this dependent dataset, the average root mean...
Data collected on benchmark soils from experimental sites in the Pianura Padano-Veneta, Northern Italy, stored in local soil data bases were used to test the reliability of existing pedotransfer functions to derive soil water retention properties, required as input to simulation models of pollutant transport in soils. Eight different algorithms were selected according to their principle of calculation,...
Simulation modelling is an important tool in evaluating the economical and environmental effects of different farm management practices. Availability and quality of input data are crucial factors that determine the accuracy of modelling results. With respect to soil water regimes, much depends on the accuracy of soil hydraulic properties. These are conventionally derived through expensive laboratory...
Soil survey data are required for different kinds of environmental and agronomic studies, especially for estimating general soil quality indicators such as Available Water Capacity (AWC) over large areas. Generally, AWC estimates take the form of a unique value per soil class, and the uncertainty pervading these estimates is not assessed, although it is of crucial importance for the users. To overcome...
Differences in land use history among taxonomically identical soils often result in different hydraulic properties, derived from either laboratory measurements or pedotransfer functions (PTFs). Additionally, flow mechanisms in sandy soils may also change through differences in water repellency associated with land use history. The soil water regimes for three sandy soils of the same taxonomic unit...
Currently, most of the research focused on general pedotransfer functions (PTFs) has been generated under humid climatic conditions. Nevertheless, this article proposes an estimation of pedotransfer functions for a great variety of climatic and physiographic conditions, with a predominance of soils developed under semi-arid conditions, such as those occurring in Spain. The results obtained, in spite...
Pedotransfer functions (PTFs) with quantified uncertainty for estimating water retention from soil structure and texture, organic carbon content, bulk density and derived variables are presented for the soils of the Pianura Padano–Veneta region of North Italy. A data set of 153 soil horizons from 59 soil profiles was used for calibration of parametric PTFs using a group method of data handling (GMDH);...
Estimates of soil water retention characteristics using pedotransfer functions (PTFs) are useful in many studies, such as hydrological modelling and soil mapping. The objective of this study was to calibrate and validate point and parametric PTF models based on neural networks and the Bootstrap method using different sets of predictors. The point PTF models estimated retention points at −1, −10, −100,...
Direct and indirect methods are available to estimate soil hydraulic properties, which are prerequisites to solve water movement equations. Direct methods are usually time consuming and require complex measuring devices, and a skilled operator compared to indirect methods. Indirect methods, e.g., pedotransfer functions (PTFs) estimate parameters based on easily obtained soil texture data, have lately...
Diffuse reflectance spectroscopy (DRS) is attracting much interest in the soil science community because it has a number of advantages over conventional methods of soil analyses. The techniques are more rapid, timely, cheaper and hence more efficient at obtaining the data when a large number of samples and analysis are required. Moreover, a single spectrum may be used to assess various physical, chemical...
The objective of this paper is to determine to what extent pedotransfer functions, PTFs, can be developed that have few coefficients and which are insensitive to soil type. The use of non-linear PTFs to predict penetrometer resistance of soils from their water status (matric potential, ψ and degree of saturation, S) and bulk density, ρ, appears to require that some other soil property, such as sand...
Soil scientists often have many covariates that they can use to predict soil properties by regression. They are ill-advised to use all available covariates uncritically, but methods for selection (whether informal or formal) that depend on data for both the predictors and the predictand are subject to selection bias. In this paper we propose an approach that uses automated methods for selecting variables,...
Direct determination of soil hydraulic properties is often costly and laborious hence the use of indirect methods such as pedotransfer functions (PTFs). Despite progress made in PTF development in general, little evaluation of PTFs has been done for the sandy soils of Niger. We tested the ability of three PTFs, (Campbell, van Genuchten, and Vauclin) to determine soil water retention and unsaturated...
Saturated hydraulic conductivity (K s ) and water retention characteristics (θ−h) of soil are needed to characterize the hydrological response of watersheds. Direct measurement of these two hydraulic properties at multiple locations in a watershed is time-consuming and costly. Alternatively, pedotransfer functions (PTFs) may be used to indirectly estimate these properties from easy-to-measure...
Characterization of soil hydraulic properties is an important step for assessing soil water regime in agricultural fields. Because direct measurement of soil hydraulic properties at multiple locations is costly and time-consuming, pedotransfer functions (PTF) are conveniently used to estimate these properties from easily measurable basic soil properties. Over the last two decades, several studies...
Mid-infrared diffuse reflectance spectroscopy (MIR-DRS, 2500 to 25000 nm) can provide rapid, cheap and relatively accurate predictions for a number of soil properties. This paper examines the ability of MIR-DRS to predict various soil chemical properties with emphasis on the elucidation of possible mechanisms of prediction. Three datasets from the states of Queensland, New South Wales, and Victoria,...
This study presents a methodology to assess uncertainties resulting from the use of pedotransfer functions (PTFs) when soil water budget is modelled at a hillslope scale. Two sources of uncertainty are examined: (i) errors in the assessment of the soil physical and chemical properties at unsampled locations, as related to the spatial spacing of the sample measurements across the entire study area,...
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