Table 4: Effects of tillage, N application and different seasons on Δ13C values (%) of wheat grain*.
Year | Conventional till (CT) | No-till (NT) | Year mean | ||
No N added (N0) | 75 kg N ha-1 (N75) | No N added (N0) | 75 kg N ha-1 (N75) | ||
1992 | 14.08 | 13.72 | 14.70 | 14.36 | 14.22 |
1993 | nd | nd | nd | nd | nd |
1994 | 14.97 | 13.78 | 15.00 | 13.95 | 14.43 |
1995 | 14.15 | 13.80 | 14.27 | 14.03 | 14.06 |
1996 | 14.90 | 14.82 | 15.25 | 15.01 | 15.00 |
Mean | 14.53 | 14.03 | 14.81 | 14.34 | 14.43 |
*Treatment effects: least significant difference at P < 0.05; year, 0.23; tillage, 0.16; N, 0.16; year × N, 0.32. Year × tillage, tillage × N and year × tillage × N interactions were not significant.