种植年限 | N (g/kg) | P (g/kg) | N/P (g/kg) |
2 | 2.99 ± 0.22a | 1.38 ± 0.04a | 2.17 ± 0.18a |
5 | 2.04 ± 0.15b | 1.07 ± 0.05b | 1.91 ± 0.08b |
8 | 1.62 ± 0.21c | 0.25 ± 0.03c | 6.57 ± 0.59b |