3.4.14 Soil Cu prediction
For Cu, the MARS model had excellent prediction accuracy (R2c=0.92; MBEc=-0.08; RMSEc=1.39; RPDc=3.02; rank=1.00) for calibration (Figure 4n). The accuracy of the prediction during validation was found the highest and more or less similar for PLSR (R2p=0.40; MBEp=-0.27; RMSEp=3.12; RPDp=1.17) and RF (R2p=0.39; MBEp=-0.09; RMSEp=3.12; RPDp=1.17). The results are concordant with those of Cozzolino & Moron (2003) and Chang et al. (2001) for soil Cu with the mPLSR model.