Data includes raw shoot biomass and yield, production and gas exchange, nodulation and N-fixation and forage quality data, including relative and consumable food values. The impacts of ozone on the growth and functioning of high-sugar ryegrass pasture mesocosms was assessed in year 2013. Pasture mesocosms, containing perennial ryegrass (Lolium perenne L) and white clover (Trifolium repens L), were grown in the early spring and exposed to ozone in solardomes from late April 2013 to the end of September 2013. Ozone (30, 35, 40, 45, 52, 67 parts per billion (ppb) treatment means) had a large effect on the pasture mesocosms. The work was carried out as part of a NERC funded PhD. Project number NEC04456. Full details about this dataset can be found at https://doi.org/10.5285/e0bcdc39-ab79-413c-bf76-d6ffbc510f15
