Economic viability of doses and split-applications of nitrogen fertilization in corn crop in a eutrophic Red Latosol/Viabilidade economica de doses e parcelamentos da adubacao nitrogenada na cultura do milho em LATOSSOLO VERMELHO Eutrofico

Nitrogen is the nutrient that is most absorbed by the corn crop, with the most complex management, and has the highest share on the cost of corn production. The objective of this work was to evaluate the economic viability of different rates and split-applications of nitrogen fertilization, as such as urea, in the corn crop in a eutrophic Red Latosol (Oxisol). The study was carried out in the Experimental Station of the Regional Pole of the Sao Paulo Northwest Agribusiness Development (APTA), in Votuporanga, State of Sao Paulo, Brazil. The experimental design was randomized complete blocks with nine treatments and four replications, consisting of five N rates: 0, 55, 95, 135 and 175 kg [ha.sup.-1], 15 kg [ha.sup.-1] applied in the seeding and the remainder in top dressing: 40 and 80 kg [ha.sup.-1] N at forty days after seeding (DAS), or A + A at 20 and 40 DAS; 120 kg [ha.sup.-1] N split in 1/2 + 1/2 or 1/3 + 1/3 + 1/3 at 20, 40 or 60 DAS; 160 kg [ha.sup.-1] N split in 1/4 + 3/8 + 3/8 or 1/4 + 1/4 + 1/4 + 1/4 at 20, 40, 60 and 80 DAS. The application of 135 kg [ha.sup.-1] of N split in three times provided the best benefit/cost ratio. The non-application of N provided the lowest economic return, proving to be unviable.