Table 3. Azotobacter and nitrifying and denitrifying bacteria’s under continuous potato cropping.
| Years of continuous cropping | Aerobic azotobacter (AA) (104 CFU /g) | Anaerobic azotobacter (ANA) (104 CFU /g) | Nitrifying bacteria (103 CFU /g) | Denitrifying bacteria(103 CFU /g) |
|---|---|---|---|---|
| CK1 | 25.48 c | 11.53 a | 0.51 b | 1.09 ab |
| CK2 | 5.27 d | 2.93 b | 0.37 bc | 1.76 a |
| CK3 | 87.23 a | 3.43 b | 0.83 a | 1.61 a |
| CK4 | 62.23 b | 3.50 b | 0.82 a | 0.82 b |
| CK7 | 30.54 c | 2.78 b | 0.33 c | 0.44 c |
Note: Different letters in the same column meant significant difference among treatments at p <0.05. CK1, CK2, CK3, CK4 and CK7 represent the values of 1–4 and 7 year continuous potato cropping soil.