EVALUATION OF DIFFERENT SOURCES AND RATES OF NITROGEN FERTILIZATION IN MAIZE (Zea mays L.)

Nitrogen fertilization is a major contributor to the increase in productivity, but also is the nutrient withthe highest rates of loss, especially when applied to the surface. The aim of this study was to evaluate different sourcesand levels of this nutrient and its effect on maize production and weight of 1000 grains. The experiment was conductedin Patos de Minas, MG, in the 2009/2010 growing season. A randomized blocks design was used, in a factorial scheme3 x 4 + control, with 13 treatments and four replications. The sources used were urea, ammonium nitrate and slowrelease urea, and doses of nitrogen applied as topdressing were 0, 40, 80, 120 and 160 kg.ha-1. After harvest, maize wasweighed and converted to 13% moisture; the mass of 1,000 grains was determined by sampling the total amount ofeach plot. No significant difference was observed between nitrogen sources at the studied conditions, however increasein doses of all sources increased production (11,083 kg for each kg.ha-1 of N added) and mass of 1000 grains (0.1025g for each kg.ha-1 of N).