Over the past two decades, concern over the effects of atmospheric nitrogen deposition on terrestrial ecosystems has led to the instigation of a number of field manipulation studies. These were reviewed in an earlier report, commissioned by English Nature. This review updates and revises that earlier report, based on a comprehensive review of all relevant published literature since 1997. This revision includes an interpretation of new data from a number of important long term field experiments in the UK, as well as additional information on interactions between nitrogen deposition and habitat management.