3.4.15 Soil Zn prediction
In case of Zn, highest and acceptable calibration predictions were recorded using the MARS (R2c=0.79; MBEc=0.01; RMSEc=0.72; RPDc=1.83) and SVR (R2c=0.78; MBEc=-0.01; RMSEc=0.69; RPDc=1.91). The later had highest prediction accuracy (R2p=0.63; MBEp=-0.07; RMSEp=0.73; RPDp=1.48) for validation which is considered as an acceptable prediction. Prediction accuracy of the R2from 0.64 to 0.84 using the airborne hyperspectral imaging and VIS-NIR spectroscopy is reported in literature (Hively et al. , 2011; Siebielec et al. , 2004; Sun et al. , 2017; Wu et al. , 2005). Chang et al. (2001) predicted Mehlich-III extractable-Zn with an accuracy of R2=0.44 using PCR model in VIS–NIR region (400–2498 nm).