Table 2. Linear combination fit (LCF) results of the Fe K-edge XANES spectra of soil colloids from various fertilisation treatments and the simulated studies a.
| Samples | LCF results (%) | LCF parameters | ||||||
|---|---|---|---|---|---|---|---|---|
| Ferrihydrite | Goethite | Magnetite | Ferrous sulfate | Ferric oxalate | R-factor | Chi-square | ||
| fertilisation treatment | Control | 23.0 ± 2.3 | 71.7 ± 1.2 | 5.3 ± 1.4 | ND | ND | 0.000042 | 3.71 × 10−5 |
| NPK | ND | 77.6 ± 1.6 | 13.8 ± 0.7 | ND | 8.7 ± 0.7 | 0.000061 | 5.34 × 10−5 | |
| NPKM | 43.4 ± 1.4 | 53.2 ± 1.1 | ND | 3.4 ± 0 | ND | 0.000054 | 4.68 × 10−5 | |
| M | 30.3 ± 2.5 | 64.3 ± 1.2 | 5.4 ± 1.6 | ND | ND | 0.000048 | 4.09 × 10−5 | |
| Simulated studies | M+10 mg/L oxalic acid | 53.1±0.013 | 47.8±1.4 | ND | ND | 11.3±0.9 | 0.000713 | 1.08×10−4 |
| M+100 mg/L oxalic acid | 49.7±3.1 | 40.9±2.5 | ND | ND | 14.4±0.6 | 0.000644 | 1.23×10−4 | |
aControl, no fertilisation;
NPK, chemical fertilisation; NPKM, chemical plus swine manure fertilisation; M, swine manure fertilisation. ND, not detected. The values of the fitting parameters (i.e., R-factor and chi-square) indicate that the fitting results are satisfactory.