Quantitative Estimation of Organic Matter Content in Arid Soil Using Vis-NIR Spectroscopy Preprocessed by Fractional Derivative

Table 2

Performance statistics of R model for calibration set and validation set based on PLSR.

Order	Principal components	Calibration set		Validation set
			RMSEC (g kg^−1)		RMSEP (g kg^−1)	RPD
0	2	0.12	10.87	0.16	8.50	1.09
0.2	2	0.28	9.84	0.23	8.13	1.14
0.4	2	0.36	9.24	0.28	7.84	1.18
0.6	2	0.38	9.11	0.28	7.87	1.17
0.8	3	0.41	8.91	0.25	8.01	1.15
1	3	0.38	9.09	0.23	8.09	1.14
1.2	4	0.42	8.79	0.36	7.42	1.24
1.4	4	0.38	9.07	0.47	6.70	1.38
1.6	4	0.42	8.84	0.51	6.47	1.43
1.8	5	0.92	3.35	0.91	2.70	3.42
2	5	0.90	3.64	0.91	2.77	3.34