Dataset on the existence of andisols under aridic-hyperthermic environments in the harrats region of the Arabian Shield

The data from twelve representative soil profiles on six harrats (two profiles from each Harrat) within the Arabian Shield are presented, including full morphological descriptions made during the field the soil survey. A number of selected physicochemical and mineralogical analyses were also conducted in the laboratory and the data were interpreted to examine the possibility of the presence of andic/vitric soil properties in the studied soils, and thus the existence of Andisols in the harrats soils. The existence of andic/vitric properties in soils is not typical of regions characterized by aridic and hyperthermic soil moisture and temperature regimes, respectively, and is probably due to the influence of paleoclimatic conditions. The data is available online for further reuse and to provide a better understanding of the findings linked to this research.


a b s t r a c t
The data from twelve representative soil profiles on six harrats (two profiles from each Harrat) within the Arabian Shield are presented, including full morphological descriptions made during the field the soil survey. A number of selected physicochemical and mineralogical analyses were also conducted in the laboratory and the data were interpreted to examine the possibility of the presence of andic/vitric soil properties in the studied soils, and thus the existence of Andisols in the harrats soils. The existence of andic/ vitric properties in soils is not typical of regions characterized by aridic and hyperthermic soil moisture and temperature regimes, respectively, and is probably due to the influence of paleoclimatic conditions. The data is available online for further reuse and to provide a better understanding of the findings linked to this research.  Fig. 1 gives an overview of some of the features and profiles in the study area. Table 1 gives detailed information for selected environmental characteristics of the selected representative soil profiles in the study area. Table 2 presents the morphological descriptions of the representative soil profiles. Tables 3  and 4 illustrate the physicochemical properties data for the representative soil profiles. Table 5 shows data from the selective dissolutions analysis and P-retention of the representative soil profiles. Table 6 shows data on the most important ratios of selective dissolutions analysis and calculated allophane and ferrihydrite concentrations for the studied profiles. Table 7 presents the index values for the andic soil properties in the studied representative profiles.

Experimental design, materials, and methods
The representative soil profiles were selected from six harrats within the Arabian Shield, Saudi Arabia. All profiles were excavated down to the C horizon and fully described in the field using the standard guidelines for soil profile description as outlined by Ref. [1]. Soil bulk density (BD) was Specifications Table   Subject Soil science: Pedology. More specific subject area Soil classification. Type of data Table, image. How data were acquired The field data for the morphological properties of the representative profiles were acquired during a soil survey, carried out in April-2017 using standard guidelines for soil profile description. Data on the physicochemical properties were acquired using standard soil laboratory methods, while the clay mineralogical composition data were acquired using selective dissolutions, XRD

Value of the Data
The data showed that andic/vitric soil properties and poorly-crystalline minerals were present in soils of the harrats region, and the soils were thus classified as Andisols.
The data is a valuable resource for pedologists and soil scientists in general to gain a better understanding of the role of paleoclimate on soil formation. The dataset can be considered a guideline and a point of comparison for future research on soils in similar geoenvironmental settings around the world. The presence of Andisols in the studied area was attributed to the influence of the paleoclimatic conditions. The data given in this article is a brief explanation of the data attributed to the research article titled "First evidence for the presence of Andisols in the dry-hot environment of the Arabian Shield" which accepted in 2019 by Geoderma (https://doi. org/10.1016/j.geoderma.2019.114068).
determined using the core method [2]. Water retention capacity (at 33 and 1500 kPa) was determined by the pressure plate method [3]. Soils were size fractionated using the pipette method [4] and the percentage of sand, silt and clay fractions were used for soil texture identification using the USDA particle size classification [5]. Soil pH was measured potentiometrically using a pH meter (ORION STAR A211) in H 2 O, 1 M KCl, 0.01 M CaCl 2 , and 1 M NaF as outlined by Ref. [5]. The calcimeter method was used to determine the total CaCO 3 equivalent [6]. Total organic carbon (TOC) was determined using the Walkley and Black wet digestion method [7]. Cation exchange capacity (CEC) and exchangeable cations were determined with extraction by the 1 M NH 4 OAc (pH ¼ 7.0) method [8]. Base saturation was calculated from the sum of bases extracted by 1 M NH 4 OAc according to Ref. [8]. P-retention was determined using the Blakemore method [5] and measured using a spectrophotometer (Palintest 9100 UV-VIS, USA). Selective dissolution analyses were performed with acid ammonium oxalate (AAO), dithionite-citrate bicarbonate (DCB) and Na-pyrophosphate for the extractable Fe, Al, and Si [9], and      measured using inductively coupled plasma optical emission spectroscopy (ICP-OES, Optima 4300 DV, PerkinElmer Inc). The allophane content was quantified using the methods of [10]. Ferrihydrite content was quantified according to Ref. [11]. Clay mineralogy was determined using an X-ray diffractometer   Parfitt and Childs (1988). a according to Parfitt and Wilson (1985) b according to Parfitt and Henmi (1982) c according to Parfitt (1990).
(MAXima_X XRD-7000, Shimadzu, Japan) and interpreted according to Ref. [12]. The surface morphology of the clay minerals was investigated using scanning electron microscopy (SEM; EFI S50 Inspect, The Netherlands) and transmission electron microscopy (TEM 1011, Joel, Japan) according to Refs. [13,14]. Volcanic glass content was determined by the point count method using a petrographic microscope as described by Ref. [5]. The soils were classified based on their properties as described by Refs. [15,16].

Transparency document
Transparency data associated with this article can be found in the online version.