Estimation of Field Scale Topsoil Properties of Agronomic Interest from Prisma Imaging Spectrometer Data

On the 22 March 2019, the Italian Space Agency (ASI) launched the PRISMA satellite, having onboard a hyperspectral imager covering the 400–2500 nm range with 234 spectral bands and about 10 nm of bandwidth. The ground spatial resolution is 30 m, plus a panchromatic camera with 5 m spatial resolution. One of the potential application areas of this scientific mission is for precision agriculture applications, among which the mapping of field-scale variability of topsoil properties is of particular interest. PRISMA clear-sky hyperspectral images were acquired in autumn and spring 2019 over two agricultural areas, Maccarese (Central Italy), and Pignola (Southern Italy). An intensive soil sampling campaign was performed, using a ground sampling scheme adapted to PRISMA spatial 30 and 5 m (PAN) resolutions, in the fields where bare soil was exposed at the satellite acquisition dates. Soil texture (clay, silt, sand) and soil organic carbon (SOC) for the collected soil samples were then determined in the laboratory. The dataset was then used to test calibration and validation of PLS (Partial Least Squares) and Random Forest (RF) regressions, developed using PRISMA surface reflectance data. To this aim, several pre-treatment tests were performed. The results show that good results could be obtained especially for clay estimation.