EPO matrix for moisture correction of field soil spectra

A dataset of 81 soil samples was collected from French, Italian, Polish, Swedish, and Swiss soil archives, where SOC measurements were available. The soil samples were air dried and sieved at 2 mm and soil spectra were collected in the country of origin using different spectroradiometers. Before collecting the soil spectra, each lab scanned the ISS LB sands. Each soil sample was split into five subsamples and placed in five petri dishes: one was left dry, while a quantity of water was added to the other four subsamples to reach 5, 10, 20 and 30 % of gravimetric soil moisture. Spectral measurements were performed in laboratory dark rooms using a contact probe and at constant temperature and humidity for all 5 subsamples and 3 replicate soil spectra were collected for each subsample and the average spectrum was computed. Two files are availble: remoistened_probefield_SSL.csv which includes the soil spectra of 81 soil samples collected at different soil moisture levels; EPO_correction_matrix.csv which includes the EPO correction matrix obtained from the re-moistened dataset. More details can be found here: https://doi.org/10.1016/j.atech.2025.101353