AMMONIA VOLATILIZATION OF UREA IN THE OUT-OF-SEASON CORN

The aim of this study was to evaluate the N losses due to volatilization at different rates of common urea, polymer coated urea and urease inhibitor-treated urea in the out-of-season corn, using semi-open static collectors. The treatments consisted of N levels on side-dressing fertilization with urea in different treatments: (a) control (without N), (b) urea 40 kg ha(-1) N, (c) urea 80 kg ha(-1) N, (d) polymer coated urea 40 kg ha(-1) N, (e) polymer coated urea 80 kg ha(-1) N and (f) urea with the urease inhibitor (UI) N 80 kg ha(-1) N. The results showed that the treatments with polymer coated urea and with urease inhibitor-treated urea reduced the volatilization of N around 50 % compared to common urea, either in the first and the second N side-dressing fertilizations. Thus, they demonstrate that the polymer coat and the urease inhibitors were effective in reducing the volatilization of urea N applied in coverage, which resulted in higher productivity. There was also increasing urease activity in the treatments with application of common urea.