The Nitrogen in Europe project adopts a multidisciplinary approach to examining and tackling the main problems of excess nitrogen. It identifies nine main problems associated with excessive nitrogen use: aquatic, coastal and terrestrial eutrophication, acidification, climate change, photochemical smog, urban air quality, particles, and stratospheric ozone depletion. The project has recently drafted a declaration on nitrogen and the food chain which you can read here. Anyone is welcome to add their name to the declaration.