The soil dataset contains 108 sample measurements from the wavelength range of 400–2500 nm (visible and near infrared spectrum) published by Rinnan et al.
Rinnan, R., & Rinnan, A. (2007). Application of near infrared reflectance (NIR) and fluorescence spectroscopy to analysis of microbiological and chemical properties of arctic soil. Soil biology and Biochemistry, 39(7), 1664--1673.