Ammonia volatilization and N-uptake from urea, urea ammonium nitrate (UAN) and Nitamin® (urea-polymer) applied to tall fescue in Georgia
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The use of urea-based fertilizers for grasslands in the southeastern U.S.A. is likely to increase as restrictions on animal manure applications are implemented. Surface application of these fertilizers commonly leads to gaseous losses of nitrogen (N), which results in low N recovery by plants. Thus, there is a need to improve the efficiency of urea-based fertilizers through new technologies, such as slow-release fertilizers. In this study, Nitamin® (slow-release urea-polymer), UAN (urea ammonium nitrate), and granular urea were tested for NH3 volatilization losses. In addition, Nitamin® and UAN were evaluated for N use efficiency with respect to ammonium nitrate (AN). On average, urea lost significantly more (p<0.05) NH3 (25% of applied N) than UAN and Nitamin® (18%) under field and laboratory conditions. In addition, Nitamin® and UAN, were approximately 70% as effective as AN in promoting tall fescue N uptake.