The present work was developed from a field experiment, conducted from February to June 2007, in the experimental area of the Jatobá Campus Jataí Unit, at the Federal University of Goiás. The soil of the site is a Distroferric Red Latosol, was grown with the Pionner 30S40 hybrid. The aim of this study was to evaluate nitrogen volatilization losses in different doses of common urea and treated with polymers and urease inhibitor in the off-season corn crop using static semi-open collectors. The experimental design was randomized blocks with 7 treatments and four replications, totaling 28 plots. The treatments consisted of urea nitrogen levels with different treatments to inhibit volatilization: 1) control, 2) urea 40 kg ha-1 of N, 3) urea 80 kg ha-1 of N, 4) polymerized urea 40 kg ha-1 N + leaf, 5) polymerized urea 40 kg ha-1 N, 6) polymerized urea 80 kg ha-1 and 7) urease inhibitor urea (UI) N 80 kg ha-1 The treatment doses were divided into two application times (half on the sixth and half on the expanded leaves, except for treatment 4 that all N was applied on the first coat). Nitrogen volatilization through absorbent foam collections was evaluated after each nitrogen application at 24 hour intervals until the third day and after the third day every 48 hours, ie at 1, 2, 3, 5, 7. 9, and 11 days after each application totaling seven collections. The collecting foams were packed in static semi-open collectors placed in each of the plots. Volatilized N-NH3 was retained in foams soaked in acidic solution and extracted with KCl solution for further quantification of losses. The results showed that the treatments with polymerized urea and urease inhibitor urea reduced N volatilization by 50% in relation to common urea, both in the first and second nitrogen coverage. Demonstrating that the urea polymerization and the urease inhibitor were efficient in reducing the urea nitrogen volatilization applied in coverage, reflecting through the higher yields obtained. There was also a higher activity of ureaase in the treatments with application of common urea.