926 ISSN 1064-2293, Eurasian Soil Science, 2019, Vol. 52, No. 8, pp. 926–934. © Pleiades Publishing, Ltd., 2019. Combined Application of Imaging Methods for Estimating Soil Physicochemical Properties F. Aghamir a, *, S. M. Hamidi b , M. M. Tehranchi b , and R. Mirzaiee c a Soil science, Faculty of Environmental sciences, Shahid Beheshti University, 16589-53571, Tehran, Iran b Laser & Plasma Research Institute and Department of Physics, Shahid Beheshti University, 16589-53571, Tehran, Iran c Department of Agroecology, Environmental Sciences Research Institute, Shahid Beheshti University, 16589-53571, Tehran, Iran *e-mail: aghamirsoil@gmail.com Received October 29, 2018; revised January 29, 2019; accepted February 15, 2019 Abstract—Traditional techniques and methods for evaluation and detection of soil samples are tedious, labo- rious, expensive, and time-consuming. In comparison, spectroscopic techniques have successfully overcome some of these disadvantages and can supplement or replace them. As soil is a complex media, it is difficult to assign specifically spectral features for physicochemical properties of soil. This study discusses the combined application of Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR), and Scanning Electron Microscopy coupled to EDX microprobe (SEM/EDX) methods for estimating soil physicochemical proper- ties. For this purpose, 30 topsoil samples were measured according to standard methods of soil analysis. All spectra were collected in the mid-infrared (MIR) from 4000 to 650 cm -1 . Chemometric methods were used in the analysis of multivariate data using the Quant2 package in OPUS 7 software and improved the prediction of soil properties using partial least squares regression (PLSR). The results showed that specific surface area (SSA MB-titration) had the best predictions for the soil properties in ATR-FTIR study with a RPD of 2.08, RMSE of 13.50 m 2 g –1 , and R 2 of 0.77 (very good); followed by cation exchange capacity, organic carbon, SSA (BET), Al, clay, and Ca (good); saturation, sand, silt/clay, electrical conductivity, saturated hydraulic conductivity, K, silt, Fe, C, and Si (fair); O, Mg, pH, bulk density, porosity, total pore volume, and particle density (poor). Also, we found that SEM-EDX is able to perform a rapid simultaneous multielement analysis without any special soil sample preparation. Consequently, modern techniques, such as ATR-FTIR and SEM-EDX can be used for such studies according to the information needed and the time required for the sample preparation. Keywords: ATR-FTIR, chemometrics, partial least squares regression, SEM-EDX, spectral preprocessing DOI: 10.1134/S1064229319080027 INTRODUCTION Soil properties are complex assemblies of minerals, organic material, living organisms, water, and gases. Many soil properties and functions emerge from inter- actions of physicochemical and biological processes at microscopic scales, but for many decades, measure- ments at this scale have remained largely unattainable. However, tremendous technological progress over the last decade has allowed soil scientists to observe and quantify the microscopic heterogeneity of soils in heretofore-unmanageable ways [16]. The mechanisms of enhanced metal sequestration and solid-phase metal speciation are quantified with a variety of high- resolution surface spectroscopy techniques including X-ray diffraction (XRD), scanning electron micros- copy with energy dispersive spectroscopy (SEM-EDS), transition electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy conducted at the premier facilities for determining the environmen- tal speciation of metals [18] might potentially over- come the cost and time-consuming efforts related to traditional laboratory analysis of many soils [10, 16]. Soil chemical and physical properties have been pre- dicted by reflectance spectroscopy successfully in the past [27, 33, 35]. As soil is a complex mixture of mate- rials, it is difficult to assign specific features of the spectra to specific chemical components [12]. Subtle differences in the spectral pattern also can indicate the presence of trace mineral or organic phases or specific features such as Fe substitution in clay minerals; such characteristics are not easily accessible by other meth- ods [21]. Near-infrared (NIR) and mid-infrared (MIR) measurements have been proposed to estimate the concentration of trace and major elements in solid samples with satisfactory results [22]. The relatively low concentration of heavy metals usually does not show absorption features in the Visible NIR (VIS-NIR) SOIL CHEMISTRY