the experiment reported in this paper was started in 1954. its object was to study the effect of various treatments on the restoration of productivity in a tract of impoverished land (glacial formation), located at the usina ester, cosmópolis county. eight treatments with four replications are being compared in randomized blocks. they are as follows: (a) control, (b) p + lime + leguminous cover crop; (c) pk + cover crop; (d) pk + lime + cover crop; (e) npk; (f) npk + lime; (g) npk + cover crop, (h) npk + lime + cover crop. ammonium sulfate, plain superphosphate, and pottassiu chloride were applied at the rates of 90, 120, and 90 kg per hectare of n, p2o5, and k2o, respectively. the cover crop used was the sun hemp (crotalaria juncea l.). the sugar cane variety planted was the c. b. 40/69. the results obtained in the first harvest of this second planting were as follows: (a) all plots receiving fertilizers gave higher yields than the control; (b) the highest yields were given by the plots receiving pk + lime + cover crop, npk + lime + cover crop, and npk + lime. the results obtained so far indicate that the best treatments improved the soil productivity, whereas there is some evidence of a decrease in productivity induced by others.