## 1 Introduction  
Non-destructive analytical techniques for soil and sediment investigation have undergone rapid development and can provide fast, low-cost, and continuous information compared to classical destructive methods [1, 2]. By studying either soil properties or sediment cores, a much higher resolution can be achieved concerning geochemistry, textural features etc. Physical and chemical properties can be studied down to nanometre resolution, marking changes even on a seasonal scale. Furthermore, highlighting significant sections on sediment cores can lead to more targeted sampling.  
In particular, X-ray-based systems, such as X-ray Fluorescence scanning and Computed Tomography scanning, have been established in the last decades as standard and common techniques. Both methods are based on the study of the wavelength that is produced by the incident of X-rays on a studied sample and the excitation of electrons that produces a movement from outer to inner shells. Later, characterization of the wavelength spectra to either specific elements or relative density can derive automatically through software. Therefore, recent studies, aim for better quantification of the prior mentioned systems, such as quantitative calibration of elemental intensities [3], internal sediment structure [4], porosity, microfauna internal and external structures [5], bioturbation [6], ichnofacies, and microfacies [7] in sediment cores as well as wave sediments structure [8, 9].  
In parallel to this field of detailed soil imaging, rapid advances are being made in various geophysical techniques for inferring the spatio-temporal variation of physical properties of the earth. These techniques are applied at various scales to obtain information on the underground structure, although at a much lower resolution than that achieved through CT and XRF scanning. However, geophysical prospecting provides an alternative means to examine soil structure at the scale of the outcrop and are easily extendable to larger scales in space and time. Thus, it is essential to test the synergetic potential of more traditional soil imaging techniques with geophysical methodologies and to assess their complementarity in studying wide areas (e.g., [10] and references therein).  
Soil/sediments exploration by electromagnetic induction (EMI) is currently a widely accepted technique in precision agriculture, geological survey, and geophysics. The main advantages of the method are that (a) it is a non-invasive one, (b) it is fast and cost-effective, and (c) all the measurements can be easily geo-referenced [11; 12]. Several studies correlate electrical conductivity (EC) with soil properties, such as percentage of clay fraction [13; 14; 15], water content [16], salt content [17], and organic matter [18]. The observed variations in soil electrical conductivity mainly depend on these soil properties. In agriculture, that can potentially influence crop growth and development [19]. For the in situ measurement of EC, several types of equipment are available. In the present study, we use GSSI EMP-400 of GSSI.  
In this study, we present the results of a comparative application of CT, XRF, and Electro-Magnetic geophysical measurements in the area of the former marsh field Agoulinitsa, currently agricultural fields, which is located in western Peloponnese, Greece (Figure 1). The first overview of XRF data and CT scanning has already been discussed [20], so in this study, we primarily focus on the results of all three methods, highlighting their synergetic and complementary character toward studying soil characteristics of the studied area.