Table 6. Soil enzyme activity under different potato–legume rotation systems.
| Years of continuous cropping | Crop rotation | Urease (mg g–1) |
Alkaline phosphatase (mg g–1) |
Hydrogen peroxidase (ml g–1) |
|---|---|---|---|---|
| one | ||||
| P–C | 73.33 a | 37.78 a | 19.57 b | |
| P–B | 71.61 a | 21.79 b | 25.19 a | |
| P–L | 44.30 b | 33.90 a | 13.78 b | |
| Two | ||||
| P–C | 77.56 a | 21.30 a | 22.88 a | |
| P–B | 73.27 a | 25.33 a | 19.19 b | |
| P–L | 42.07 c | 18.62 b | 17.82 b | |
| Three | ||||
| P–C | 39.48 a | 18.80 a | 14.76 a | |
| P–B | 20.58 c | 20.17 a | 15.03 a | |
| P–L | 43.41 a | 17.17 b | 14.52 a | |
| Four | ||||
| P–C | 51.60 a | 32.70 a | 12.00 b | |
| P–B | 34.32 b | 23.67 b | 19.53 a | |
| P–L | 38.87 b | 21.67 b | 14.55 b | |
| Seven | ||||
| P–C | 36.88 b | 27.98 b | 11.87 a | |
| P–B | 53.81 a | 37.23 a | 9.22 b | |
| P–L | 39.41 b | 24.96 b | 10.39 b |
Note: Different letters in the column meant significant difference among treatments at p <0.05. P–C, P–B and P–L refer to Potato–Common vetch, Potato–Black medic and Potato–Longdong alfalfa, respectively.