Eficiência de dispersantes na análise textural de materiais de solos com horizonte B latossólico e B textural

Abstract

Soils materiais (B horizons) from 19 distinct profiles (10 with Bo horizon and 9 with Bt horizon) were studied aiming to verify the efficiency of some chemical dispersers,sodium hidroxide, calgon (sodium hexametaphosphate), and calgon + sodium carbonate , using different mechanical skakings, in the presence and absence of abrasive agent (coarse sand). A completely randomised experimental design was used with a 2 x 3 x 2 factorial scheme, that is two methods of clay determination (pipette and hydrometer), three dispersers (NaOH, (NaP03)x, and (NaPO-) + Na-CO-J and presence and absence of abrasive agent (coarse sand) and with three replications. These analysis were performed using fast and slow shaking for each soil material. The dispersers efficiency was evaluated through the clay percentage. The data revealed that the sodium hydroxide was the best disperser for the oxic horizons while sodium hydroxide and calgon had similar action for the argillic horizons, stressing the need of taking into account the soil class. It was also verified that associated to the chemical process of dispersion there is a need of a good chemical action which was obtained with the slow shaking in the presence of abrasive agent.