Table 6.

Independent holdout validation set RMSE values for local and global RF models¹.

Global/Local	Preprocessing method	pH	m3.Al	m3.Ca	Total carbon	Clay	Sand
CACSS	First derivative	0.6	177.77	998.58	0.43	12.5	12.94
	MSC	1.93	485.64	6042.29	1.23	18.48	22.36
	Second derivative	0.53	180.77	868.19	0.51	12.72	13.07
	SNV	0.65	215.27	1561.67	0.67	13.11	14.46
	SNV + Detrend	0.72	232.86	1242.18	0.52	13.02	14.08
HQISS	First derivative	0.61	189.67	902.61	0.42	11.39	11.36
	MSC	1.61	366.5	4943.63	1.24	18.16	20.27
	Second derivative	0.5	182.29	726.07	0.41	11.71	11.2
	SNV	0.66	216.99	1177.52	0.52	12.76	13.96
	SNV + Detrend	0.67	217.83	1243.51	0.51	12.61	13.98
Archetype-SS	First derivative	0.52	321.11	1116.33	0.42	18.25	22.77
	MSC	0.59	389.06	1269.76	0.64	20.35	24.18
	SNV	0.56	360.29	1533.73	0.73	20.15	24.12
	SNV + Detrend	0.6	370.35	1478.75	0.65	20.37	24.04
SOM-SS	First derivative	0.62	209.12	1078.02	0.41	11.46	12.33
	MSC	1.25	428.17	3311.35	0.86	18.6	17.36
	Second derivative	0.52	192.98	954.05	0.45	11.48	11.67
	SNV	0.66	212.3	941.39	0.48	12.29	13.69
	SNV + Detrend	0.71	212.27	923	0.5	12.67	13.37
Global	First derivative	0.60	164.42	888.38	0.42	11.42	11.51
	MSC	2.09	403.42	5711.57	0.95	18.71	21.68
	Second derivative	0.49	169.8	813.06	0.41	11.27	12.18
	SNV	0.63	205.32	1190.2	0.53	12.56	13.88
	SNV + Detrend	0.69	208.9	1188.51	0.49	12.28	13.57

¹Bold figures show local models, which are better than global models. Global model values have been italicized for clarity.