Resumo

BUFFA, Eduardo V  e  RATTO, Silvia E. Pseudototal Copper, Zinc, Iron and Manganese content in soils for assessing the geochemical background of the Chaco-Pampean Plain of Cordoba, Argentina. Cienc. suelo [online]. 2009, vol.27, n.2, pp.185-198. ISSN 1850-2067.

Data on the total nutrient content of soils is essential for assessing potential fertility and is fundamental to environmental and edaphogenetic studies. The aim of this paper was to measure Cu, Zn, Fe y Mn in soils of the Chaco Pampean Plain in Argentina using the simultaneous acid nitric (HNO₃ 4 M) extraction procedure (called pseudototal) to infer geochemical background and geochemical baseline data by analysing surface and subsurface samples. The results can be related with other edaphic features such as organic carbon, acidity, salinity and carbonates. Average values of 11.3 to 19.2 mg Cu kg-¹, 29.4 to 61.5 mg Zn kg-¹, 285 to 626 mg Mn kg-¹ g-¹ and 9 to 19.9 g Fe kg-¹ were found at a soil depth of 0-60 cm, falling within the range reported in worldwide literature. The lowest values were found in sandy soils. The values at a soil depth of 0-20 cm were 17 mg Cu kg-1, 55 mg Zn kg-¹, 562 mg Mn kg-¹ and 16 g Fe kg-¹ in loessic and loam loessic soils and 12 Cu kg-¹, 36 mg Zn kg-¹, 347 mg Mn kg-¹ and 11 g Fe kg-¹in loam sandy soils. The textural difference between loessic and sandy soils reflects different background values for the four elements studied, the lowest values corresponding to sandy soils. Multiple regression analysis included Fe and Mn as the main variables to explain the amounts found for each of the four elements at each depth which is related to the high affinity between transition metals and their tendency to co-precipitate as low cristallinity oxides.The second variable in most of the models for the studied elements was organic carbon, confirming the importance of organic matter as a primary source of these micronutrients.

Palavras-chave : Background value; Baseline; Cu; Zn; Fe; Mn; Nitric acid; Córdoba; Argentine.

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