Table 4.
Crop N uptake and recovery efficiencies with different N control measures.
| Treatments | Wheat | Maize | ||||
|---|---|---|---|---|---|---|
| Nitrogen fertilizer (kg ha-1) | Nitrogen uptake (kg ha-1) | Nitrogen recovery efficiency (%)a | Nitrogen fertilizer (kg ha-1) | Nitrogen uptake (kg ha-1) | Nitrogen recovery efficiency (%) | |
| CK | 0 | 199b | - | 0 | 183b | - |
| FN | 285 | 247a | 16.7e | 392 | 235a | 13.5d |
| RN | 225 | 255a | 24.7d | 300 | 244a | 20.3bc |
| CRF | 225 | 265a | 29.2c | 300 | 239a | 18.9c |
| CRF80% | 180 | 257a | 32.3bc | 240 | 241a | 24.5ab |
| RN80%+DCD | 180 | 267a | 38.0a | 240 | 249a | 27.7a |
| RN80%+NC | 180 | 264a | 35.9ab | 240 | 243a | 25.3a |
aNRE (%) = (Plant N content with N fertilizer-Plant N content without N fertilizer)/N fertilizer rate × 100. Treatments of CK, FN, RN, CRF, CRF80%, RN80%+DCD and RN80%+NC represent the corresponding treatments as described in Table 1. Means followed by different letters in the same column for wheat or maize indicate significant differences between treatments according to one-way ANOVA followed by Duncan’s multiple range test (P ≤ 0.05).