Electrochemical attributes of soils influenced by sugarcane vinasse / Atributos eletroquímicos de solos influenciados pela vinhaça

ABSTRACT

The electrochemistry at the surface of colloidal particles in soils is related to important physical and chemical phenomena, such as flocculation and dispersion of soil particles, cation-exchange-capacity, anion adsorption, pesticides and heavy metals adsorption. Sorption of organic compounds on the surface of soil components may cause important changes on their electrochemical attributes. The vinasse has been applied in soils, mainly in sugarcane crops, as organic fertilizer. Its effects on physical, chemical and biological attributes of soils are well documented; however, little is known about the effects on electrochemical attributes. This work aimed to evaluate the effects of sugarcane vinasse on soil pH and zeta potential of the clay fraction of two Latosols (Oxisols) and an Argisol (Ultisol). The pH of soils amended with vinasse was measured in water and 1M KCl solution (ratio soil:water 1:2.5), and estimated the ∆pH (pH 1M KCl - pH in water). The zeta potential (ζ)) of the clay fraction was determined by electrophoretic mobility in 0,01M NaCl solution adjusted to different pH values (2, 3, 5, 6, 7, 9 and 11), and estimated the point of zero charge (PZC) (ζ) = 0). The soil pH and net charge of soils were clearly influenced by vinasse. These changes may influence important chemical and physical phenomena in soils and also help future studies involving vinasse in soils.