Formas de micronutrientes em solos da regiao cacaueira da Bahia

Abstract

The distribution of different forms of Zn, Cu, Mn, Fe and Mo was investigated in eight typical soil profiles from the cocoa region of Bahia, Brazil. In general, the distribution of the total contents of trace elements in the profile was associated with clay distribution. In most of the samples analyzed the concentration of the available fraction was higher at surface horizons in association with organic matter. Among the elements analyzed for total content, Fe presented the highest concentration and Mo the least. The following order can be indicated: Fe major Mn major Zn major Cu major Mo. The total content of Mo was relatively low and was detected only by HClO4, 60 per cent method. In the case of the available form of trace elements, the amount extracted varied with the extracting solutions used. In general, Mn and Fe showed the highest concentrations, followed by Zn and Cu, whereas Mo was not detected in a significant amount. Among the extractants for available fractions, the following general order can be indicated: 0.1 N HCl major, equal 1 per cent Na2-EDTA major N NH4OAc pH 4.8 major N NH4OAc pH 7.0