A regression model for nitrate leaching in Northern Ireland

A model has been developed based on multiple regression which explains 95% of the variation in nitrate loading of the major rivers in the 4453 km 2 Lough Neagh catchment for the years 1971–1987. The model relates loading of nitrate in the hydrological year to fertilizer usage, previous summer rainfall, summer temperature of the current year and December‐May flow. It indicates that there is an increase in nitrate loading associated with fertilizer usage, and that the equivalent of 13% of nitrogen fertilizer that is lost as leachate comprises 50% of the river loadings.