Ultrasonic Dispersion of Brazilian Soil Samples Influenced by Vinasse.

Vinasse is the main byproduct of the ethanol and sugarcane spirit industry; it has been applied to soils as organic fertilizer. The objective of this work was to evaluate the effect of vinasse application and incubation time on dispersion of soils material by ultrasonic energy. The soils (dystroferric RED LATOSOL, dystrophic RED-YELLOW LATOSOL and RED-YELLOW ARGISOL) were sampled at 0-10 cm depth. Soil columns (PVC tubes, 12-cm long and 4-cm internal diameter) were fist packed with 200 g of soil and then treated with increasing doses of vinasse (0 - control, 150 and 300 m³ ha^-1) and incubated for 1, 30 and 60 days. After each incubation time, the soil samples were submitted to different levels of ultrasonic energy and quantified clay, silt and sand contents of soils. Soil dispersion index (SDI) was calculated for each ultrasonic energy level, by relation between the clay + silt dispersible and the mass of sample before sonication and plotted against energy levels in order to obtain the soil dispersion curves. The results showed that increasing dose of vinasse and incubation time reduced the dispersion of all three soils. The soil dispersion curves were reasonable to identify differences on soil dispersion as affected by vinasse and incubation time. The effects of vinasse on soil dispersion were related with the changes on the colloidal properties.