Soil chemical properties of a toposequence under primary rain forest in the Itacoatiara vicinity (Amazonas, Brazil)

Nine soil profiles of a typical toposequence under primary rain forest of the Amazon area were investigated, distinguishing between Geric Ferralsols (Xanthic Kandiudox) in the upper and middle parts of the slope and Geri-Haplic Arenosols (Oxyaquic Quartzipsamments) in the lower ones, Generally, the soils are strongly acid with very high Al contents and show extremely low nutrient contents, In spite of this conformity, significant differences were found referring to the agricultural suitability along the toposequence, The decrease of soil potentials from the top to the lower positions is mainly due to the variation of texture.