| Year | CK | N | P | NP |
---|---|---|---|---|---|
Available C&N&P | |||||
 DOC (mg·kg− 1) | 2014 | 299.2 ± 8.3 a | 281.6 ± 6.1 a | 310.4 ± 19.1 a | 314.1 ± 28.3 a |
2015 | 294.8 ± 2.8 b | 288.9 ± 5.5 b | 316.0 ± 3.1 a | 324.3 ± 5.3 a | |
 MBC (mg·kg− 1) | 2014 | 571.7 ± 3.8 a | 557.1 ± 3.5a | 589.3 ± 2.9 a | 588.2 ± 19.6 a |
2015 | 563.4 ± 15 ab | 545 ± 10.3 b | 593.2 ± 4.8 a | 587.0 ± 1.7 a | |
 NH4+ (mg·kg− 1) | 2014 | 8.1 ± 0.2 b | 10.9 ± 0.6 a | 6.8 ± 0.1 b | 7.4 ± 0.5 b |
2015 | 7.7 ± 0.1 a | 8.7 ± 0.6 a | 6.7 ± 0.1 b | 8.1 ± 0.03 a | |
 NO3− (mg·kg− 1) | 2014 | 38.4 ± 0.9 b | 42.4 ± 1.1 a | 35.0 ± 0.3 c | 37.1 ± 0.9 bc |
2015 | 40.6 ± 0.1 b | 48.1 ± 2.3 a | 36.9 ± 0.3 b | 41.6 ± 0.7 b | |
 AP (mg·kg− 1) | 2014 | 27.5 ± 8.4 b | 24.8 ± 4.3 b | 149.3 ± 11.9 a | 150.6 ± 21.4 a |
2015 | 29.3 ± 3.6 b | 22.3 ± 4.1 b | 139.4 ± 12.8 a | 131.9 ± 9.8 a | |
Soil cations | |||||
 Soil pH | 2014 | 4.7 ± 0.04 a | 4.5 ± 0.07 a | 4.6 ± 0.03 a | 4.5 ± 0.1 a |
2015 | 4.6 ± 0.08 a | 4.2 ± 0.04 b | 4.4 ± 0.1 b | 4.3 ± 0.01 b | |
 Al3+ (mmol·kg− 1) | 2014 | 38.0 ± 1.0 c | 50.2 ± 1.0 a | 42.4 ± 0.8 b | 44.8 ± 0.9 b |
2015 | 38.4 ± 3.2 c | 60.4 ± 0.4 a | 48.7 ± 0.8 b | 61.0 ± 1.4 a | |
 Ca2+ (mmol·kg− 1) | 2014 | 33.6 ± 3.1 a | 25.1 ± 1.8 b | 28.8 ± 0.3 ab | 25.0 ± 0.7 b |
2015 | 30.3 ± 2.9 a | 20.1 ± 0.5 c | 26.0 ± 0.2 ab | 22.6 ± 0.5 bc | |
 Mg2+ (mmol·kg− 1) | 2014 | 4.7 ± 0.4 a | 4.3 ± 0.2 a | 4.2 ± 0.4 a | 4.2 ± 0.1 a |
2015 | 4.2 ± 1.0 a | 3.5 ± 0.6 a | 3.7 ± 0.1 a | 3.3 ± 0.1 a | |
 Na2+ (mmol·kg− 1) | 2014 | 1.5 ± 0.2 a | 1.4 ± 0.04 a | 1.3 ± 0.3 a | 1.3 ± 0.2 a |
2015 | 1.2 ± 0.2 a | 1.3 ± 0.4 a | 1.2 ± 0.1 a | 1.2 ± 0.1 a | |
Plant | |||||
 Fine root biomass (g·m− 2) | 2014 | 172.2 ± 1.3 a | 147.4 ± 4.0 c | 161.9 ± 0.7 b | 152.2 ± 1.5 c |
2015 | 178.9 ± 1.9 a | 142.6 ± 1.7 d | 159.7 ± 1.4 b | 148.6 ± 1.2 c |