Hyperspectral reflectance (%) data across named wavelengths measured using a portable spectroradiometer May and June 2018 at a long-running grassland experiment in southern England (Nash's Field). The data are organised by row, one for each 2 x 2 m subplot (n = 96). Each subplot is assigned to a factorial treatment. The treatments include herbivory (with and without pesticides), grazing (with and without fences), soil pH (with and without lime), plant competition (with and without herbicides) and soil fertility (with and without fertilisers). Full detail of the split-plot design of this long-running experiment is available at https://doi.org/10.5281/zenodo.13345223 Also included for each subplot is the number of plant species recorded and the dried above-ground biomass of plant material harvested within a 50 x 50 cm quadrat placed in the centre of each plot.