| Plotb | Total organic matter | Humic acid | Fulvic acid |
| Humic acid | |
| (g C kg−1 dried soil) | Δlog Kc | RFc | ||||
| F | 10.2 | 4.29 | 3.69 |
| 0.690 | 44 |
| F + LC | 13.6 | 6.67 | 4.11 |
| 0.750 | 35 |
| F + HC | 22.7 | 12.1 | 5.42 |
| 0.827 | 27 |