Cattle ranching is one of the main economic activities in the agrosystem of Itapetinga, state of Bahia, Brazil. This activity is known to cause direct impacts on soil, subsoil and vegetation. This study aimed at verifying changes in soil chemical characteristics and texture under different vegetation covers in the cattle ranching region of Itapetinga by sampling soils in a primary forest-secondary forest-pasture sequence. Soil samples were collected along a transect with 36 small trenches, 60 cm deep, spaced 5 m apart (12 samples taken from soil under primary forest, 12 from soil under secondary forest and 12 from soil under pasture) in the 0-10 cm, 10-20 cm and 20-40 cm soil layers. Every three sampling points along the transect were grouped to a composite sample. The results were subjected to analysis of variance and the averages were compared by the Tukey's test at 5 % significance. Differences were observed in the chemical properties and organic matter concentration of the soils under study. Changes in the original vegetation cover, from the primary forest to pasture, led to a reduction in the levels of phosphorus, potassium, calcium, magnesium, aluminum, hydrogen, sum of bases, base saturation and cation exchange capacity, indicating that, in general, these parameters were affected by the introduction and use of pastures. Significant differences were observed in the soil texture according to the vegetation type; clay content increased in the across the primary forest-secondary forest-pasture sequence, and the greater proportion of sand was found for soils under pasture.
primary forest; pasture; sum of bases; base saturation; CEC; texture
