THE "gross overstocking" of sheep as a result of EU funded headage payments is blamed by the EPA report for causing, "severe damage" to upland habitats, particularly those of the red grouse, golden plover and hen harrier.
It says overgrazing particularly affects peatlands, heaths and coastal habitats, with the loss of characteristic and rare flora and fauna. Mountain areas in particular are suffering from "excessive sheep stocking densities".
The consequent soil gradually extends the area of bare rock as well as loading rivers and lakes with silt, it explains. "Peat silt can directly affect species such as the protected freshwater pearl mussel and has indirectly caused mortality of between 20,000 and 30,000 eggs in a fish hatchery".
The report notes that sheep numbers more than doubled from 3.3 million in 1980 to 8.8 million in 1991. Reforms in the EU Common Agricultural Policy led to a 2.3 per cent drop in sheep numbers from 1992 to 1993 - too small to have an impact on overgrazing, it says.
Other principal changes in agriculture since the early 1980s include almost a doubling of silage production, increased use of nitrogen fertilisers, decreased tillage and a rapid increase in afforestation.
The £230 million Rural Environmental Protection Scheme, which is regarded as an important agri environment measure, has not yet made an impact on this problem as the take up in the areas of greatest need - the degraded uplands, particularly in the west - "has not been great".
The EPA notes that agriculture "contributes to the unrelenting trend of increased slight to moderate pollution of rivers due to eutrophication (over enrichment) and says a "sustained effort", is needed to reduce nutrient releases from farming.
It is estimated that agriculture in Ireland produces as much waste as 68 million people. However, the report emphasises that this is the generated BOD (biochemical oxygen demand) load and not the amount of waste discharged to waters - but this "has not been possible to estimate".
It notes that silage has been implicated in fish kills and slurry run off linked to the enrichment of waters. "Virtually the sole disposal route for agricultural slurries in Ireland is land spreading. Codes of practice have been drafted which, if followed, can minimise the risk of water pollution".
The increased incidence of fish kills in 1995, following on a substantial reduction in previous years, underlined the need for a sustained effort to reduce the pollution caused by agriculture, which the EPA identifies as one of the main sources excess phosphate in rivers and lakes.
"On a national basis, much more phosphorous than is, required for optimal production is being used in intensive agriculture", it says, adding that farmers could save £25 million or more in fertiliser costs each year by cutting back "without any adverse effects on farm production".
The average phosphorous level in soils has increased by a factor of 16 over the past 40 years. The use of nitrate has also been rising inexorably, though about 72 per "cent of the amount applied to the land by farmers may be dissipated to water and to the atmosphere.
The report says that nitrate is of considerable public health significance, with the potential to impair significantly the oxygen transporting functions of the blood. High nitrate concentrations in drinking water constitute a health hazard to babies in particular and may also be carcinogenic.
On forestry, it notes that trees planted are mainly North American conifers, which had the potential for environmental degradation.