Remote sensing holds vast potential for precision and smart farming and for field phenotyping applications. We present a small, but high-quality dataset consisting of ground truth, handheld spectrometer (proximal) and drone (remote sensing) data gathered in one of the world’s oldest long-term field experiments (>70 yrs). The proximal and the remote sensing approaches showed comparable performance. Medium to strong correlations with the ground truth parameters were shown. Long-term field experiments are a valuable source for sensor calibration, calibration and validation of remote sensing products and applications. Vice versa, remote sensing methods and technology can support, improve and enhance data acquisition in field trials, particularly in long-term experiments.