This paper assesses the capability of an spectrometer used in field experiments of soybean, maize and wheat. The objective of this work is to select different wavelengths intervals of the spectral reflectance curve, within the range 632-1125 nm, as features for classification using machine learning methods. Two different classifications are presented, species selection and growth stage identification. For species classification accuracy of 92% is reached, while 99% is obtained for stage classification. In addition we propose a new index that outperforms analyzed established vegetation indices, which shows the potential advantage of using this type of devices.Sociedad Argentina de Informática e Investigación Operativa