TABLE 2.
Test results of the fixed main effects in the generalized linear mixed models for soil carbon fractions.
| Management |
Soil layer |
Soil analysis |
|||
| Depth (cm) | SOCa (%) | C/N | POM-Ca | Cmica (mg C kg–1) | |
| Crop sequence | |||||
| Monoculture | 0–5 | 2.99 | 11.38 | 69.90 | 432.4(a) |
| Crop rotation | 0–5 | 3.05 | 11.35 | 72.42 | 463.2(b) |
| Tillage system | |||||
| Plow | 0–5 | 2.68a | 11.40 | 56.76a | 347.0a |
| Reduced tillage | 0–5 | 3.01b | 11.46 | 73.78b | 471.4b |
| No-till | 0–5 | 3.36c | 11.23 | 82.95c | 524.9c |
| Crop sequence | |||||
| Monoculture | 5–10 | 2.68 | 11.50 | 53.85 | 328.11 |
| Crop rotation | 5–10 | 2.76 | 11.38 | 55.48 | 339.17 |
| Tillage system | |||||
| Plow | 5–10 | 2.69 | 11.47 | 54.99(a) | 313.80a |
| Reduced tillage | 5–10 | 2.75 | 11.75 | 56.82(a) | 348.25b |
| No-till | 5–10 | 2.71 | 11.12 | 52.18(b) | 338.87b |
| Crop sequence | |||||
| Monoculture | 10–20 | 2.56 | 11.28 | 47.94 | 301.97 |
| Crop rotation | 10–20 | 2.63 | 11.38 | 50.11 | 307.83 |
| Tillage system | |||||
| Plow | 10–20 | 2.71a | 11.44 | 54.22a | 329.62a |
| Reduced tillage | 10–20 | 2.48b | 11.36 | 44.47b | 281.93b |
| No-till | 10–20 | 2.59c | 11.19 | 48.37b | 303.14c |
aSOC, soil organic carbon; POM-C, particulate organic matter carbon; Cmic, microbial biomass carbon. The different letters refer to statistically significant differences within each comparison; p ≤ 0.05, (p ≤ 0.10). The number of observations (n) is 24 for each response variable.