| This paper is concerned
with nitrogen inputs to European catchments, how they are likely to change in
future, and the implications for the INCA model. National N budgets show that
the fifteen countries currently in the European Union (the EU-15 countries)
probably have positive N balances – that is, N inputs exceed outputs. The
major sources are atmospheric deposition, fertilisers and animal feed, the
relative importance of which varies between countries. The magnitude of the
fluxes which determine the transport and retention of N in catchments is also
very variable in both space and time. The most important of these fluxes are
parameterised directly or indirectly in the INCA Model, though it is doubtful
whether the present version of the model is flexible enough to encompass
short-term (daily) variations in inputs or longer-term (decadal) changes in soil
parameters. As an aid to predicting future changes in deposition, international
legislation relating to atmospheric N inputs and nitrate in rivers is reviewed
briefly. Atmospheric N deposition and fertiliser use are likely to decrease over
the next 10 years, but probably not sufficiently to balance national N budgets.
Keywords: nitrogen deposition, nitrogen fertilisers, nitrogen budgets,
nitrogen balance, nitrate leaching, INCA Model, environmental legislation,
EU directives, air pollution, water pollution |