Table 3.
Near infrared reflectance spectroscopy calibration and validation results for all studied elements.
| Elements | Calibrationa |
Validationb |
Factors | Spectrum region (cm-1) | Preprocessingc | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Rc | RMSEE | RPD | Rv | RMSEP | RPD | Bias | ||||
| N (g 100 g-1) | 0.98 | 0.09 | 7.89 | 0.99 | 0.06 | 10.9 | 0.0004 | 11 | 6102-4598 | MMN |
| K (g 100 g-1) | 0.94 | 0.09 | 3.95 | 0.88 | 0.12 | 2.86 | 0.0063 | 17 | 7502-4598 | FD + VN |
| Ca (g 100 g-1) | 0.98 | 0.25 | 6.39 | 0.98 | 0.25 | 6.94 | 0.0627 | 13 | 7502-4598 | FD |
| Mg (g 100 g-1) | 0.84 | 0.05 | 2.52 | 0.89 | 0.05 | 2.97 | -0.0007 | 8 | 7502-4248 | MMN |
| B (mg kg-1) | 0.56 | 59.00 | 1.51 | 0.47 | 53.20 | 1.38 | 0.0521 | 6 | 11996-7498 | MSC |
| Fe (mg kg-1) | 0.77 | 44.00 | 2.1 | 0.76 | 60.40 | 2.04 | -3.23 | 15 | 7502-5446 | MMN |
| Cu (mg kg-1) | 0.22 | 1.29 | 1.13 | 0.36 | 1.47 | 1.22 | 0.12 | 4 | 5450-4248 | MMN |
| Mn (mg kg-1) | 0.77 | 4.99 | 2.08 | 0.53 | 5.55 | 1.46 | -0.394 | 12 | 11996-6098 | — |
| Zn (mg kg-1) | 0.84 | 3.23 | 2.49 | 0.88 | 3.34 | 2.84 | 0.0683 | 17 | 7502-5446 | VN |
aRc, coefficient of determination for calibration; RMSEE, root mean square error of estimation; RPD, calculated as the SD divided by the SE of prediction.
bRv, coefficient of determination for validation; RMSEP, root mean square error of prediction; Bias, difference between the mean real value and the mean estimated value for the validation set samples.
cPreprocessing: VN, vector normalization; MSC, multiplicative scatter correction; FD, first derivative; MMN, minimun–maximun normalization; —, no treatment.