To evaluate the decrease in infiltration rate in crusting soils an experiment was carried out using a rainfall simulator. Treatments were distributed in a factorial schedule 5 x 6, using five soils (Red Ultisol, Red-Yellow Ultisol, Red-Yellow Oxisol, Fluvic Entisol and Arenic Entisol) and six rainfall kinetic energies (0, 525, 1051, 2102, 3153, and 4204 J m-2) with three replications. According to the water infiltration rate and crust thickness, as determined by micromorphometry, the crust hydraulic conductivity and hydraulic resistance were calculated. The crust hydraulic resistance increased with the kinetic energy of the rain (especially for Red-Yellow Ultisol and Red Ultisol) up to a maximum value. The following decrease of crust hydraulic resistance was attributed to the crust erosion caused by increasing runoff. Multiple regression analysis determined the relationship of crust hydraulic resistance with the rainfall kinetic energy as well as the chemical and physical characteristics of each soil. The hydraulic resistance appeared to be an appropriate variable to be used in models of water infiltration in the soil to describe the crust influence on this process.
crusting; rainfall simulator; crust hydraulic resistance
