[EN]: In connection with the study on mineralogy of the soil in the valley of the Guadalquivir, we are commenting and reporting the results obtained with the sand fractions of different types of soil (xerorrendsines, gleyzed brown loam, red calcareous loams and andalusian black earths) in Ecija (Seville). Xerorrendsines are the less developed soils, they have highest proportion of calcium carbonate in their profile, and the smallest relation between heavy and light minerals in its sands. The andalusian black earth has the highest grade of chemical erosion, the less amount of CaCO3 and a higher proportion of heavy minerals in relation to light minerals. The red calcareous loams and the brown gleyced one corresponding to relictus formation occupy un intermediate position in the grade of chemical erosion; the former close to the black earths and the latter to the xerorrendsines. The characteristic association of heavy minerals is the fol1owing: garnet-andalusite- zircon-turmaline, minerals of great resistance to chemical erosion. The presence of these minerals is according to the petrographic region surrounding this part of the valley of the Guadalquivir. Likewise the presence of this association of heavy minerals in the soils we are studying agrees with the analogy of the parent geological material. Other heavy minerals, such as staurolite, rutile, hornblende, hiperstene, distene, epidote, etc. vary in frequence from common to rare. When the heavy opaques minerals are found in upper horizonts more frequently, the show an increase of chemical erosion in this direction. The proportion of feldespts plus mica decreases in this relation: Xerorrendsines-brown loam-red loams-black earths. This fact shows again the growing degree of chemical erosion. The reducing conditions in the gleyzed brown loam profile determine a higher concentration of ferrous minerals (hornblende, hiperstene) which shows that existenee of Fe2+ and its oxidation possibility to Fe3H is an important factor in the determination of the capacity of erosion of these minerals.

[ES]: En la determinación de las propiedades generales y particulares de los suelos, de las que dependen tanto su definición y caracterización general como sus cualidades más importantes relacionadas con su aprovechamiento y empleo práctico, desempeña un papel importante el conocimiento de su composición mineralogica. La naturaleza y proporción de los minerales componentes afecta a los procesos mismos de que depende el desarrollo y evolución de los suelos, pero influye de un modo especial en sus propiedades físicas y químicas, razón por la cual el estudio mineralógico de las diversas fracciones de los suelos ha adquirido en los últimos tiempos un interés insospechado.

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Peer reviewed