Table 2.
Regression models and parameters for the relationships between nitrous oxide (N2O) emission and nitrogen uptake (GNU, TNU), nitrogen recovery efficiency (NRE), net nitrogen balance (NNB), and surplus nitrogen (SN) based on the individual observations when management focused on N rate alone.
| Variables | Regression Parameters | ||||
|---|---|---|---|---|---|
| N | Model | Equation | R2 | P < F | |
| GNU | 84 | Linear | y = −0.065+0.011x | 0.215 | <0.0001 |
| 84 | Exponential | y = 0.430exp(0.008x) | 0.172 | <0.0001 | |
| TNU | 84 | Linear | y = 0.147+0.006x | 0.178 | <0.0001 |
| 84 | Exponential | y = 0.459exp(0.005x) | 0.162 | <0.0001 | |
| NRE | 62 | Linear | y = 2.064−0.013x | 0.136 | 0.0031 |
| 62 | Exponential | y = 2.414exp(−0.011x) | 0.135 | 0.0033 | |
| NNB(GNU) | 80 | Linear | y = 0.676+0.008x | 0.328 | <0.0001 |
| 80 | Exponential | y = 0.706exp(0.007x) | 0.297 | <0.0001 | |
| NNB(TNU) | 78 | Linear | y = 1.080+0.008x | 0.244 | <0.0001 |
| 78 | Exponential | y = 1.0066exp(0.007x) | 0.228 | <0.0001 | |
| SN | 84 | Linear | y = 1.350+0.009x | 0.311 | <0.0001 |
| 84 | Exponential | y = 1.263exp(0.008x) | 0.308 | <0.0001 | |
N, Number of individual observations; GNU, grain nitrogen uptake; TNU, total nitrogen uptake.