Table 5.
Nitrogen source effects on seasonal nitrous oxide emission, nitrogen recovery efficiency (NRE), net nitrogen balance [NNB(TNU)], fertilizer induced emission factor (FIEF), and emission reduction (ER) in selected locations across North America.
| Location | N Source | □ Nitrous oxide and N uptake parameters | ||||
|---|---|---|---|---|---|---|
| N2O (kg N ha−1) | NRE (%) | NNB(TNU) (kg ha−1) | FIEF (%) | ER (%) | ||
| Colorado | ESN | 0.92b | 53.9a | 23.2a | 0.36b | 19.3 |
| Stabilized urea§ | 0.59c | 56.3a | 11.86a | 0.21bc | 48.2, 20.3 | |
| UAN | 0.74bc | 50.7a | 19.3a | 0.29b | . | |
| Urea | 1.14a | 54.3a | 21.52a | 0.45a | . | |
| Indiana (rainfed) | UAN | 2.35a | 52.7 a | 19.8a | 1.23a | . |
| UAN+nitrapyrin | 1.69b | 57.6a | 9.1 a | 0.58b | 28.1 | |
| Minnesota (rainfed, irrigated) | ESN | 1.17ab | 48.1a | −21.6a | 0.44ab | 19.9 |
| Stabilized urea | 0.86b | 52.7a | −27.6a | 0.26b | 41.1 | |
| Urea | 1.46a | 52.2a | −25.4a | 0.60a | . | |
N2O and N uptake parameters data from Colorado consisted of 8 site -years (2007–2014) under irrigation; Indiana: 4 site-years (2010–2013) in rainfed condition; and Minnesota: 5 site-years (2008–2012) in rainfed and irrigated conditions. §Emission reduction for Colorado calculated relative to urea ammonium-nitrate (UAN) and urea, respectively; NNB(TNU) = net nitrogen balance based on total N uptake. Within location and column, N2O and N uptake parameters followed by the same letters are not significantly different at P = 0.05.