Soil chemistry soils studies the behavior of the mineral fraction of weathered tropical soils, including electrochemistry, development of charges and adsorption phenomenon. Because of the broad spectrum to be covered in the understanding of the behavior of mineral fraction added to the methodological difficulties, the study of complex soil organic fraction was relatively less developed. The current proposal revisits the early works related to the chemistry of tropical soils with the objective to relate them with electrochemical data of soil carbon stocks. The objective of this study was to review aspects of soil electrochemistry, to determine and to relate the points of zero charge by different methods, the potentials of the electric double layer and the electrochemistry of humus of Brazilian modal soils in a typical sequence of weathering, aiming to generate information for their management and conservation. The methods for estimating the point of zero charge of the soils show different results, but with the same trend among soils. There is a predominance of negative charges on both layers of soils. The negative charges of the colloids are significantly associated with the availability of electrons from the humus and both decrease with the weathering stage of the soil.
electrochemistry; ionic exchange; organic matter; point of zero charge; soil chemistry
