Mineralogical characterization of Pozuzo District's soils through physical techniques

Abstract

We introduce a study on soils in three different fields of plantations in Pozuzo District, Oxapampa province, Peru. Two of the fields are cultivated and the third one has a degradation problem. In situ, in all, we collected 29 samples in the three plantations. We utilized analytical and physical techniques, namely, energy dispersive X-ray fluorescence, X-ray diffractometry, and transmission Msbauer spectroscopy; we complemented our research with a physical-chemical analysis to determine texture, pH, content of organic matter and cation interchange capacity. For all analyzed samples, the results of the analysis by energy dispersive X-ray fluorescence show the presence of the following elements: Si, Cl, K, Ca, Ti, Cr, Mn, Fe, Cu, Zn, Rb, Sr and Zr. By X-ray diffractometry, we observe the structural phases associated with quartz, montmorillonite, illite, microcline, kaolinite, muscovite, and iron oxides such as goethite and hematite. By using transmission Msbauer spectroscopy, we observe the presence of magnetic sextets assigned to Fe³⁺ from hematite ; doublets associated with Fe³⁺ and Fe²⁺, respectively, localized in illite and/or interstratified montmorillonite; similarly, we observe other states attributed to a Fe³⁺ site. The results of the physical-chemical analyses of the plantations are of great importance to determine the soil conditions. Furthermore, a low level of organic matter is observed with a pH ranging from 4.6 to 6.0, what limits the nutrient absorption by the plants.