Resistência hidráulica da crosta formada em solos submetidos a chuvas simuladas

SUMMARY : CRUST HYDRAULIC RESISTANCE IN SOILS UNDERSIMULATED RAIN To evaluate the decrease in infiltration rate in crusting soils an experiment was carriedout 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 andArenic 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, asdetermined by micromorphometry, the crust hydraulic conductivity and hydraulic resistancewere 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 followingdecrease of crust hydraulic resistance was attributed to the crust erosion caused by increasingrunoff. Multiple regression analysis determined the relationship of crust hydraulic resistancewith the rainfall kinetic energy as well as the chemical and physical characteristics of eachsoil. The hydraulic resistance appeared to be an appropriate variable to be used in modelsof water infiltration in the soil to describe the crust influence on this process.Index terms: crusting, rainfall simulator, crust hydraulic resistance.