objective. to assess the effect of different doses of lime in acid sulphate soils and physiological responses of two species of grasses, cynodon nlemfuensis vanderyst and brachiaria decumbens stapf. materials and methods. the work was carried out during 2006 in acid sulfate soils at el deseo farm (ciénaga de oro - córdoba, colombia), where 3, 6 and 9 tons/ha of agricultural lime was applied and two grass species, cynodon nlemfuensis vanderyst (pasto estrella) and brachiaria decumbens stapf (pasto brachiaria) were planted. the responses considered during 5 mowings were the chemical features of the soil, fresh and dry weight of each genotype and the leaf/stem ratio. an experiment of complete random blocks was designed using a structure of divided plots, where the main plots corresponded to the grasses and the subplots to the lime doses. results. the most outstanding results suggested that the ph values and aluminum in the soil concentrations fall significantly with the quantity of applied lime, decreasing up to 80%. in general, the interchangeable bases increased with the lime dosage and the contents of the microelements decreased considerably over time, although this was not evident for the lime. independently of genotype, the production of fresh biomass showed a linear relationship within lime dosage (y=0,656x + 11,99; r2=0.92); the dry mass and the leaf/stem ratio were always greater for b. decumbens compared to c. nlemfuensis, independent of lime dosage.