Nitrogen fertilization is very important to wheat crop, since nitrogen constitutes one of the most demanded nutrients by this crop, which yield is directly related to the amount of nutrients accumulated in the plant. Three nitrogen sources were tested at 70 kg N ha-1: ammonium sulfonitrate with nitrification inhibitor, ammonium sulfate, and urea in two applications (at sowing or at side dressing), besides a control that did not receive nitrogen as treatment. Four wheat cultivars were tested: EMBRAPA 21, EMBRAPA 22, EMBRAPA 42, and IAC 370. The experiment was carried out under irrigation in two years (2005 and 2006) at Experimental Station of UNESP/São Paulo - Brazil. The N sources ammonium sulfonitrate, ammonium sulfate, and urea did not differ among them; however, they were higher than the control regarding the grain yield. N applied at side dressing provided an increase in grain yield. The cultivar performance concerning the production and grain yield depended on the environmental condition of the year.
Triticum aestivum L.; nitrogen fertilizer; urea; ammonium sulfate; ammonium sulfonitrate
