TEORES DE NUTRIENTES NO SOLO E NUTRIÇÃO MINERAL DO MILHO EM ÁREAS IRRIGADAS COM ÁGUA CALCÁRIA

Abstract

In order to study the effect of nitrogen sources upon the yields and nutrition of corn for silage and on the chemical attributes of a Cambisol, at Northern of Minas Gerais, Brazil, under calcareous water. The cultivar used was Decalb 390®, with a spacing of 0,8 m x 0,2 m. The base fertilization consisted in 330 kg ha-1 of formulation 4-30-10 and 50 kg ha-1 of FTE-BR12. Two equal dosages of 40 kg ha-1 of K2O, in the KCl form, were applied 45 and 60 days after corn sowing (DAS), phenologic phases V7 and V10 . The experiment it was realized in a randomized blocks design with six repetitions, been the treatments constituted by: ammonium sulfate (topdressing manuring), urea (topdressing manuring), Crotalaria juncea (before de maize crop). The Nfertilizers were applied parceled into three equal dosages of 40 kg ha-1, 30 DAS, with 15 days between fertilizations. The corn yields increased above control treatment average in 33, 27 and 14 t ha-1 with ammonium sulfate and urea topdressing and with C. juncea pre cropped, respectively. The ammonium sulfate use allows better recovery rate of the N applied by the extractor and higher uptake of Fe, Mn, Zn and S by the corn plants.