The influence of P, K, and NPK on some plant and ear characters was studied in two experiments conducted for various years at Campinas. The effects of the mentioned nutrients, which were very high on the total grain yields, manifested by increasing the number of plants which attained maturity, their size and the proportion of those bearing ears, as well as the weight of the ears and their shelling percentages. While the fertilizers affected considerably most of the characteristics studied, they modified only slightly the shelling percentage; however, irrespectively of the treatments, these percentages varied remarkably in the different years. Based on these results the authors suggest means for estimating the grain yields in outlying experiments, where the determination of the shelling percentage for each plot is frequently impracticable.