Sediment production and soil water infiltration under different simulated rainfall characteristics/ Producao de sedimentos e infiltracao de agua no solo sob diferentes caracteristicas de chuva simulada

The study was carried out to evaluate sediment production, water infiltration and surface runoff in an Ultisol under simulated rainfalls with similar erosivity, but different combinations of intensity (Int) and duration (Dur). The rainfalls were applied after soil tillage in the period from August to September 2017, in Seropedica, RJ State, Brazil. Using a computer program, the treatments were defined from the erosivity calculated for a rainfall with intensity of 60 mm [h.sup.-1] and duration of 60 min, resulting in the other combinations of Int and Dur: 44.5 mm [h.sup.-1] and 106 min; 53.5 mm [h.sup.-1] and 78 min; 66.9 mm [h.sup.-1] and 48 min; and 76.5 mm [h.sup.-1] and 38 min, in a completely randomized design with five repetitions. Sediment production varied from 2.17 to 6.11 g [m.sup.-2], respectively, in the treatments with Int 53.5 mm [h.sup.-1] and Dur 78 min and Int 44.5 mm [h.sup.-1] and Dur 106 min. Stable infiltration rate (mm [h.sup.-1]) were 21.6, 37.7, 31.4, 29.5, and 22.4, respectively, in the treatments Int 44.5 mm [h.sup.-1] and Dur 106 min; Int 53.5 mm [h.sup.-1] and Dur 78 min; Int 60.4 mm [h.sup.-1] and Dur 60 min; Int 66.9 mm [h.sup.-1] and Dur 48 min; and Int 76.5 mm [h.sup.-1] and Dur 38 min. The different combinations of intensity and duration of rainfalls with similar erosivity change sediment production, but do not significantly influence surface runoff and water infiltration in the soil. Key words: erosivity, rainfall intensity, rainfall duration, surface runoff O estudo foi realizado com objetivo de avaliar a producao de sedimentos, a infiltracao da agua e o escoamento superficial em um Argissolo Vermelho-Amarelo sob chuvas simuladas com erosividades semelhantes, mas com distintas combinacoes de intensidade de precipitacao (Int) e duracao (Dur). As chuvas foram aplicadas apos o preparo do solo e no perlodo de agosto a setembro de 2017 em Seropedica, RJ, Brasil. Utilizando um programa computacional, os tratamentos foram definidos a partir do calculo da erosividade para uma chuva de 60 mm [h.sup.-1] e 60 min de duracao, resultando nas demais combinacoes de Int e Dur: 44,5 mm [h.sup.-1] e 106 min; 53,5 mm [h.sup.-1] e 78 min; 66,9 mm [h.sup.-1] e 48 min; e 76,5 mm [h.sup.-1] e 38 min, em delineamento inteiramente casualizado com cinco repeticoes. A producao de sedimentos variou de 2,17 a 6,11 g [m.sup.-2], respectivamente, nos tratamentos com Int 53,5 mm [h.sup.-1] e Dur 78 min e Int 44,5 mm [h.sup.-1] e Dur 106 min. As taxas de