Soil chemical and physical characteristics were evaluated on a Rhodic Nitisol Eutrophic clayey located in Passo Fundo, Rio Grande do Sul State, Brazil in a trial of agronomic performance of three perennial summer grasses (kikuyu grass, elephant grass and Tifton 68 grass) for milk production after two growing seasons. The trial used a complete randomized block design replicated three times. Soil samples were also taken in a fragment of subtropical forest near the experiment. Soil reaction (pH), aluminum, calcium, magnesium, and phosphorus varied according to the studied soil layer. Some grasses increased the level of phosphorus content in all layers. Pastures increased accumulated carbon levels in the 0-20 cm layer in comparison to subtropical forest. No differences among grass species were observed for soil organic matter contents. Soil bulk density and soil mechanical resistance did not differ among pastures in both sampling layers. However, in the 0-5 cm layer (and in the 10-15 cm), these values increased in comparison to the subtropical forest. Total porosity and macroporosity did not differ among of three grass species, but the values were respectively lower and greater in comparison to soil forest.
kikuyu grass; Pennisetum clandestinum; elephant grass; P. purpureum; Tifton 68; Cynodon nlemfuensis
