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

João Carlos Medeiros,Yves Coquet,Jaqueline Dalla Rosa,Miguel Cooper,Michel Grimaldi

doi:10.1590/s0100-06832014000300005

Abstract

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.

Highlights

The term pedotransfer function (PTF) was first introduced by Bouma (1989) to describe the statistical relationship between easy-to-measure soil properties, such as particle size distribution, bulk density (Bd), soil organic carbon (SOC), and so on, and difficult-tomeasure soil hydraulic properties, such as the soil water retention curve (SWRC), hydraulic conductivity, etc
According to Vereecken et al (2010), the PTFs can be classified into two types: parametric PTFs that estimate the empirical parameters of the SWRC (Vereecken et al, 1989; Wösten et al, 1999; Navin et al, 2009; Gould et al, 2012) and point PTFs that are used to estimate soil water content at different matric potentials (Gupta & Larson, 1979; Saxton et al, 1986; Reichert et al, 2009)
Papers published in recent years highlight the usefulness of parametric PTFs (Vereecken et al, 2010) because they directly provide the required hydraulic parameters to be used in mathematical models that describe the movement of water and solutes in soil, as well as the soil-plant-atmosphere interactions

Summary

Introduction

The term pedotransfer function (PTF) was first introduced by Bouma (1989) to describe the statistical relationship between easy-to-measure soil properties, such as particle size distribution, bulk density (Bd), soil organic carbon (SOC), and so on, and difficult-tomeasure soil hydraulic properties, such as the SWRC, hydraulic conductivity, etc. According to Vereecken et al (2010), the PTFs can be classified into two types: parametric PTFs that estimate the empirical parameters of the SWRC (Vereecken et al, 1989; Wösten et al, 1999; Navin et al, 2009; Gould et al, 2012) and point PTFs that are used to estimate soil water content at different matric potentials (Gupta & Larson, 1979; Saxton et al, 1986; Reichert et al, 2009). In Brazil, Arruda et al (1987) were pioneers in relating soil particle size distribution to soil water content. Tomasella & Hodnett (1998) produced functions for Amazonian soils to estimate the empirical parameters of the SWRC proposed by Brooks & Corey (1964). Using data from reports of soil surveys of various locations in Brazil, Tomasella et al (2000)

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Conclusion