spectra of near-infrared reflactance of soil available N, P, K

The spectral reflectance measurements of soil samples were captured using a near-infrared hyperspectral camera. The number of spectral bands is 224, and the spectral range is 935 nm -1720 nm. The average spectrum for each sample was extracted from the region of interest (ROI) within the soil sample using ENVI 5.3. Two spectral data were captured from each side of the soil sample. A total of 223 spectral data were collected, except that spectrum from one side of a sample was not captured because the surface was damaged by careless treatment. The spectral data were then calibrated with dark and white reference images.The spectral data were randomly divided in a ratio of 8:2. Specifically, 178 spectra were selected as the training dataset, and 45 spectra were selected as the test dataset. Owing to the noise perturbations of the edge band effect, the bands  at the end of the spectra were removed, leaving 210 bands for each spectrum (953 nm -1688 nm).