Estratégias de aplicação e doses de nitrogênio para o milho cultivado em solo argiloso.

Abstract

Nitrogen utilization by maize is dependent on the rate and time at the nutrient issupplied. The objective ofthis study was to evaluate the maize morphological and productive aspectsin a clayey Oxisol. The experiment was carried out under field conditions in the Iraí de Minas - MGin irrigated area. A randomized complete block design was used in a 5 x 2 + 1 factorial scheme,with four replications. The treatments consisted of five N rates (0, 50, 100, 150 and 200 kg ha-1)associated with two application times (pre-sowing and sidedressing) and an additional treatmentreferring to the fertilization adopted by the farm. The pre-sowing application was performed 15 daysbefore sowing and the sidedressing when the plants had 4 - 5 fully expanded leaves. The farmfertilization consists ofthe 35 kg ha-1ofN, 139 kg ha-1ofP2O5and 70 kg ha-1ofK2O at sowing andtwo applications of50 kg ha-1ofN in sidedressing, the first was performed 17 days after the plantsemergence and the second 10 days after the first application. Urea was used as the source ofN. Itwas concluded that the N application in pre-sowing was efficient under the edaphoclimaticconditions considered. The Nrate of200 kg ha-1provided the highest crop yield.