Clay fraction characterization of the soil profile of a quinoa plantation by X-ray diffraction and Mössbauer spectroscopy

X-ray diffractometry (XRD) and Mössbauer spectroscopy (MS) were used to study the clay fractions of soil profile samples from the quinoa (Chenopodium quinoa Willd.) plantations at the Salcedo Experimental Station of the National Institute of Agrarian Innovation located in the southern Peruvian plateau. The sample extraction was made at 40 cm intervals from 20 cm to 180 cm in depth, and the clay fraction was obtained by the Stokes’ law. In addition, the tests of the physical and chemical properties were included, such as pH, organic matter, and humidity, which present values that increase in relation to the depth from 6.75 to 8.09, 4.31% to 6.25%, and 5.38% to 27.08% respectively, and with class texture of sandy loam (first three) and clay loam (remaining two samples). The XRD results showed the presence of phases such as quartz, montmorillonite, andesine and hematite. The room temperature MS spectra were fitted using four paramagnetic sites, doublets, and one magnetic site, sextet. The hyperfine parameters for the sextet are compatible with hematite. Three of the paramagnetic sites were assigned to montmorillonite, two in the octahedral sites, trans and cis configurations, and one at the edge site. The presence of hematite and montmorillonite were confirmed at low temperature; in addition, a second sextet was observed with hyperfine parameters that were compatible with goethite. © 2024, The Author(s), under exclusive licence to Springer Nature Switzerland AG.