A COMPARISON OF AGRICULTURAL WATER-POLLUTION INCIDENTS IN NORTHERN-IRELAND WITH THOSE IN ENGLAND AND WALES

Agricultural pollution incidents in Northern Ireland declined by 51% b etween 1987 and 1995. This decline resulted from a steady decrease in the largest category of farm pollution, silage effluent, which decline d by 78%. The decline in silage pollution was most evident in the mont hs of May and June and may be related to an observed increase in grass wilting, which reduces silage effluent volumes, and favourable weathe r during these months. Non-silage related incidents were 49% greater i n 1995 than in 1987 and showed no particular trend with time nor the d istinct annual cycle that was observed for silage pollution. Silage ef fluent represented 51% of all pollution sources, followed by a general category of farm effluent (27%) and cattle slurry (12%). No other sou rce contributed more than 4% of the total. An analysis of pollution ca ses showed that, while incidents associated with leaking and overflowi ng effluent tanks and leaking silos all declined, incidents where no e ffluent collection facilities were found increased. This increase was considered to be the result of a change in detection efficiency rather than an absolute increase in the number of farms without effluent col lection facilities. Farm pollution statistics from Northern Ireland an d England and Wales demonstrated similar trends for both silage and no n-silage related incidents, with no evidence to suggest that increases in financial penalties for causing pollution or different levels of g rant aid had impacted or? long-term trends. Trends in pollution statis tics from catchments in Northern Ireland targeted for pollution advice by agriculture advisory staff did not differ from the area as a whole . (C) 1998 Elsevier Science Ltd. All rights reserved.