Resumo

CASTRO, Liliana N et al. The glauconitic levels of the Salamanca Formation, Chubut: its agronomic effectiveness as a potassium fertilizer alternative. Rev. Asoc. Geol. Argent. [online]. 2010, vol.66, n.3, pp.391-398. ISSN 0004-4822.

The Maastrichtian-Early Palaeocene Salamanca Formation and equivalent marine sequences show several glaucony levels, which could be used as a source of potassium and could partially replace current fertilizer requirements met from import. First agronomic assays are shown comparing the efficiency of greensands (GL) with a traditional potassium fertilizer (KCl). Prospection and sampling took place in the heads of Rio Chico to east of Lago Colhué Huapi, Chubut, where glauconitic levels thickness reach to 20m. This research was separated in phases: phase 1, prospection, sampling, and sedimentological and chemical routine analyses, phase 2a, concentration and ore treatment assays, and phase 2b, agronomic assays. This last phase, was done in culture chamber, with 125 μm and 250 μm fractions (2,85 and 2,82 % K2O respectively) and KCl. Varying the dose, seven treatments were completed. In successive harvests (four in total) was observed that GL1 and GL2 (125), did not present a significantly differential behavior with the control. Both treatments of GL 250 μm showed major accumulated biomass, overcoming the control in 44 and 60 % respectively. As conclusion, better results were obtained by 250 μm overcoming even to the KCl fertilization. Probably the major participation of K feldspars in the 125 μm and fast leaching of K in this fraction during successive irrigations of soil would originate the minor observed yield. The great areal extension of the Salamanca Formation and the continuity of the glauconitic levels encourage continuing the evaluation as fertilizer or amendment.

Palavras-chave : Glauconitic sandstones; Potassium fertilizer; Salamanca Formation; Potassium alternative sources.

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