Two idealised Se budget scenarios have been generated to assess the role of atmospheric cycling on the Se status of UK agricultural grasslands. Based on a thorough literature review, the budgets demonstrate that varying the factors for losses by volatilisation from plants and soils or inputs by deposition may significantly affect the net balance of a grassland. The contribution of wet, dry, vapour and particulate deposition inputs to the soil-herbage system are assessed and are thought to be dominated by a soluble form in wet deposition. The total input is calculated to be typically in the range 0.2-0.7 mg m^-2 year^-1. Volatile losses from the soil are difficult to derive accurately, but are estimated to range between 0.1 and 10 mg m^-2 year^-1. The budget suggests there is a net input of Se to herbage from the atmosphere, even in remote/rural locations, where inputs are generally low. The implications for the availability of Se to plants and grazing livestock are briefly considered.