Table 2. Grain yield (dry matter, Mg ha−1) of each crop from October 2010 to September 2013.
| Treatment# |
Winter wheat |
Summer maize |
Annual yield |
|||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Nitrogen | Straw | 2011 | 2012 | 2013 | 2011 | 2012 | 2013 | 2011 | 2012 | 2013 |
| Treatment effect (n = 3) | ||||||||||
| N0 | S | 2.7 ± 0.4§b¶ | 2.4 ± 0.3b | 2.5 ± 0.1b | 5.4 ± 0.4b | 3.9 ± 0.4c | 4.8 ± 0.3c | 8.1 ± 0.4c | 6.3 ± 0.3b | 7.3 ± 0.2c |
| N0 | 2.9 ± 0.4b | 2.5 ± 0.4b | 2.7 ± 0.4b | 5.0 ± 0.3b | 4.5 ± 0.6c | 5.0 ± 0.3c | 7.9 ± 0.5c | 7.0 ± 0.6b | 7.7 ± 0.2c | |
| Nopt | S | 5.4 ± 0.6a | 4.3 ± 0.6a | 4.5 ± 0.3a | 6.5 ± 0.4ab | 6.1 ± 0.3b | 5.9 ± 0.4b | 11.9 ± 0.5ab | 10.4 ± 0.5a | 10.5 ± 0.4b |
| Nopt | 5.4 ± 0.2a | 4.7 ± 0.4a | 4.7 ± 0.2a | 5.9 ± 0.6b | 6.5 ± 0.4ab | 7.0 ± 0.3a | 11.3 ± 0.7b | 11.9 ± 0.7a | 11.7 ± 0.2a | |
| Ncon | S | 5.5 ± 0.1a | 4.5 ± 0.4a | 4.7 ± 0.1a | 6.5 ± 0.3ab | 7.3 ± 0.4a | 7.0 ± 0.2a | 12.0 ± 0.3ab | 11.8 ± 0.4a | 11.7 ± 0.2a |
| Ncon | 5.7 ± 0.5a | 4.6 ± 0.4a | 4.5 ± 0.4a | 7.9 ± 0.3a | 7.3 ± 0.3a | 7.1 ± 0.2a | 13.5 ± 0.5a | 11.9 ± 0.4a | 11.6 ± 0.4a | |
| Nitrogen effect (n = 6) | ||||||||||
| N0mean | 2.8 ± 0.3b | 2.4 ± 0.3b | 2.6 ± 0.2b | 5.2 ± 0.2b | 4.2 ± 0.5c | 4.9 ± 0.1c | 8.0 ± 0.3b | 6.7 ± 0.8c | 7.5 ± 0.3b | |
| Noptmean | 5.4 ± 0.3a | 4.5 ± 0.2a | 4.6 ± 0.2a | 6.2 ± 0.5ab | 6.3 ± 0.2b | 6.5 ± 0.1b | 11.6 ± 0.6a | 10.8 ± 0.4b | 11.1 ± 0.2a | |
| Nconmean | 5.6 ± 0.4a | 4.6 ± 0.4a | 4.6 ± 0.1a | 7.2 ± 0.4a | 7.3 ± 0.3a | 7.1 ± 0.4a | 12.7 ± 0.7a | 11.9 ± 0.7a | 11.7 ± 0.2a | |
| Straw effect (n = 9) | ||||||||||
| Without straw | 4.5 ± 0.1a | 3.7 ± 0.4a | 3.9 ± 0.1a | 6.1 ± 0.2a | 5.8 ± 0.3a | 5.9 ± 0.3a | 10.7 ± 0.1a | 9.5 ± 0.7a | 9.8 ± 0.3a | |
| With straw | 4.6 ± 0.3a | 3.9 ± 0.2a | 4.0 ± 0.2a | 6.3 ± 0.3a | 6.1 ± 0.3a | 6.4 ± 0.1a | 10.9 ± 0.3a | 10.0 ± 0.5a | 10.3 ± 0.2a | |
| Treatment effect (n = 3) | ||||||||||
| Nopt | S | 5.2 ± 0.2a | 4.7 ± 0.4ab | 4.7 ± 0.2a | 5.9 ± 0.6c | 6.5 ± 0.4b | 7.0 ± 0.3b | 11.3 ± 0.7b | 11.9 ± 0.7b | 11.7 ± 0.2b |
| Mbal | S | 5.4 ± 0.5a | 5.3 ± 0.4a | 4.8 ± 0.5a | 9.4 ± 0.6a | 9.9 ± 0.7a | 8.2 ± 0.4a | 14.6 ± 0.6a | 15.3 ± 0.7a | 13.1 ± 0.2a |
| Wbal | S | 5.7 ± 0.3a | 5.3 ± 0.5ab | 4.7 ± 0.1a | 7.7 ± 0.5b | 9.2 ± 0.6a | 7.9 ± 0.3a | 13.4 ± 0.5ab | 14.5 ± 0.6a | 12.7 ± 0.9ab |
#N0, Nopt, Ncon, Mbal and Wbal represent control, improved Nmin test, conventional farming practice, cattle manure with N balance method and waste compost with N balance method, respectively. S represents straw returning.
§Number represents mean ± standard error.
¶Means followed by the same letter are not significantly different (P < 0.05).