A spectrometric measuring head for harvesting machines and other agricultural equipment comprises a housing with a window, in which a light source, a spectrometer arrangement and at least two standards for internal recalibration are provided. The standards can optionally be swiveled in the optical path of the measuring head such that the entire measuring light coming from the light source is used for recalibration. A processor that captures and processes the measured values and an interface to a bus system are arranged in the housing.