3.4.6 Soil P prediction
The relationship between the observed and predicted P for calibration
revealed MARS to predict the P with acceptable prediction accuracy
(R2c=0.80; MBEc=-1.12;
RMSEc=10.75; RPDc=1.80 and rank=1.00).
These predictions were classified as good. The prediction accuracy for
the validation using PLSR was observed as non-reliable with
R2p=0.33; MBEp=-3.41;
RMSEp=19.09; RPDp=0.89. The best overall
rank of 2.25 was recorded for the PLSR (Figure 4f). Xu et al.(2018) reported comparably better prediction accuracy based on SVMR and
BPNN model for total phosphorus (TP) with
R2=0.35-0.81. Similarly, Udelhoven et al. ,
(2003), Cozzolino et al. , (2013), Hu (2013) and Schirrmannet al. (2013) also reported possibilities of P prediction using
spectroscopy through multivariate modeling.