The relationship between inputs and outputs of nitrogen in intensive grassland systems.- The response to nitrogen fertilizer from a cut perennial ryegrass (Lolium perenne L.) pasture in the Scottish uplands relative to efficiency of fertilizer use and provision of herbage for animals.- Efficient use of fertilizer nitrogen on grass swards: effects of timing, cutting management and secondary grasses.- Nitrogen supply and the persistence of grasses.- Sources and transformations of organic nitrogen in intensively managed grassland soils.- Gaseous losses of nitrogen from grassland.- Relationships between soil mineral nitrogen content and denitrification, following application of slurry and calcium nitrate to grassland.- Losses of nitrogen from intensive grassland systems by leaching and surface runoff.- Nitrate loss through leaching and surface runoff from grassland: effects of water supply, soil type and management.