The response of corn to mineral fertilizers was studied in a series of trials conducted for four consecutive years at Campinas and Ipanema, and for five consecutive years at Engenheiro Hermilo. Ten different treatments were compared, and the basic fertilizer treatment (1-1-1) had 25, 25, and 45 kg/ha of N, P2O5, and K2O, applied respectively as ammonium sulphate, superphosphate, and potassium chloride. Corn responded best to phosphorus, as it can be seen ir: figures 1 and 2. The average yield increase per hectare in the three localities, due to the application of 75 kg/ha of P2O5, was as follows : Campinas, 620 kg ; Ipanema, 1,380 kg ; and Engenheiro Hermilo, 1,540 kg. Nitrogen increased corn yields only at Campinas and Ipanema. Potash did not induce any response in the three above-mentioned localities. There were indications that the application of the fertilizer in the furrows at planting time, although it was thoroughly mixed with the soil, impaired the stand in dry years.