Table 3: Performance of model fits using spectra of samples under field conditions, evaluated with leave-one-out cross validation.

pH

Total P (mg/100 g)

Total K (mg/100 g)

Total N (%)

Total N (%)

Total C (%)

Total C (%)

Moisture (%)

Method

PLSR

PLSR

PLSR

PLSR

SMLR

PLSR

SMLR

PLSR

No. of factors

4

2

2

2

4

4

8

1

0.45

0.16

0.44

0.34

0.43

0.45

0.74

0.11

RMSE CV

0.48

34.93

314.73

0.40

0.39

8.38

6.03

12.7

RPD CV

1.35

1.09

1.35

1.24

1.28

1.37

1.90

1.05

RMSE CV: root mean square error of cross validation, RPD CV: ratio of performance to deviation of cross validation, PLSR: partial least squares regression, SMLR: stepwise multiple linear regression.