Table 4. Nitrate leaching rate (kg N ha−1) of each crop at 100 cm soil depth.
| Treatment# |
Winter wheat |
Summer maize |
Annual |
|||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Nitrogen | Straw | 2011 | 2012 | 2013 | 2011 | 2012 | 2013 | 2010–2011 | 2011–2012 | 2012–2013 |
| Treatment effect (n = 3) | ||||||||||
| N0 | S | 0.1 ± 0.2§c¶ | 0.4 ± 0.5c | 0.1 ± 0.1c | 1.4 ± 0.3c | 3.6 ± 2.5b | 0.8 ± 0.6c | 1.6 ± 0.2c | 4.0 ± 2.7b | 0.9 ± 0.7c |
| N0 | 0.2 ± 0.1c | 0.6 ± 0.4c | 0.4 ± 0.3c | 1.6 ± 0.2c | 2.7 ± 0.6b | 2.1 ± 0.8c | 1.8 ± 0.2c | 3.3 ± 0.4b | 2.5 ± 0.9c | |
| Nopt | S | 1.0 ± 0.1a | 1.6 ± 1.1b | 1.6 ± 0.9b | 27.7 ± 2.7b | 10.6 ± 4.7b | 10.9 ± 5.1b | 28.7 ± 2.9b | 12.2 ± 4.4b | 12.5 ± 5.5b |
| Nopt | 0.8 ± 0.6a | 2.2 ± 1.2b | 1.6 ± 1.1b | 21.3 ± 7.9b | 10.2 ± 1.4b | 12.1 ± 5.1b | 22.2 ± 8.6b | 13.4 ± 1.5b | 13.7 ± 4.5b | |
| Ncon | S | 0.6 ± 0.2ab | 3.9 ± 1.9a | 3.2 ± 1.2a | 41.4 ± 6.8a | 33.9 ± 14.1a | 18.3 ± 5.5ab | 41.9 ± 7.0ab | 37.8 ± 14.7a | 21.4 ± 5.7ab |
| Ncon | 0.9 ± 0.3a | 4.4 ± 2.7a | 3.2 ± 2.0a | 59.3 ± 18.2a | 42.0 ± 13.5a | 21.9 ± 6.8a | 60.2 ± 18.9a | 46.4 ± 14.4a | 25.1 ± 7.2a | |
| Nitrogen effect (n = 6) | ||||||||||
| N0mean | 0.2 ± 0.1b | 0.5 ± 0.5c | 0.3 ± 0.2c | 1.5 ± 0.1c | 3.2 ± 1.0c | 1.4 ± 0.7c | 1.7 ± 0.1c | 3.7 ± 1.1b | 1.7 ± 0.8c | |
| Noptmean | 0.9 ± 0.4a | 1.9 ± 1.1b | 1.6 ± 1.0b | 24.5 ± 4.5b | 10.4 ± 2.5b | 11.5 ± 4.1b | 25.4 ± 4.7b | 12.8 ± 2.9b | 13.1 ± 4.0b | |
| Nconmean | 0.7 ± 0.3a | 4.1 ± 2.5a | 3.2 ± 1.6a | 50.3 ± 11.1a | 38.0 ± 8.9a | 20.1 ± 1.0a | 51.0 ± 11.7a | 42.1 ± 10.0a | 23.3 ± 1.3a | |
| Straw effect (n = 9) | ||||||||||
| Without straw | 0.6 ± 0.2a | 2.0 ± 1.1a | 1.6 ± 0.2a | 23.5 ± 3.1a | 16.1 ± 4.8a | 10.0 ± 1.0a | 24.1 ± 3.0a | 18.0 ± 5.0a | 11.6 ± 0.2a | |
| With straw | 0.6 ± 0.4a | 2.4 ± 0.9a | 1.7 ± 0.3a | 27.4 ± 6.2a | 18.3 ± 3.8a | 12.0 ± 2.1a | 28.0 ± 7.0a | 21.0 ± 4.2a | 13.8 ± 3.1a | |
| Treatment effect (n = 3) | ||||||||||
| Nopt | S | 0.8 ± 0.6a | 2.2 ± 1.2a | 1.6 ± 1.1a | 21.3 ± 7.9a | 10.2 ± 1.4a | 12.1 ± 5.1a | 22.2 ± 8.6a | 13.4 ± 1.5a | 13.7 ± 4.5a |
| Mbal | S | 1.5 ± 1.0a | 2.8 ± 1.3a | 2.3 ± 1.7a | 30.4 ± 13.4a | 17.2 ± 5.5a | 16.2 ± 5.1a | 31.9 ± 12.8a | 20.0 ± 4.2a | 18.5 ± 3.6a |
| Wbal | S | 1.1 ± 0.1a | 1.8 ± 0.9a | 1.2 ± 1.1a | 27.0 ± 8.6a | 17.2 ± 7.1a | 9.1 ± 4.1a | 27.1 ± 7.6a | 19.0 ± 6.3a | 10.3 ± 2.6a |
#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).