Water Quality Status – Still Stagnant!

Damien Gibbons, Walsh Scholar, Teagasc Ballinrobe

The protection of water quality from nutrient, sediment and pesticide losses and achieving ‘Good Status’ for all waters in Ireland is a key national goal. Agriculture is just one of a number of human activities that can put pressure on water quality. Other activities impacting water quality include hydromorphology (physical changes to waters), urban and domestic waste water, forestry, peat extraction, industry and roads.

However, agriculture is the largest pressure on water quality in Ireland as it is the largest land use in the country. Nutrient, sediment and pesticide losses to water from agricultural practices are the greatest stressors on the quality of our waterbodies and most recent findings from the EPA (Environmental Protection Agency) have shown that overall improvements in water quality are still not being achieved, as any improvements are being offset by declines. Nitrogen is too high in 40% of river sites and in 20% of estuarine and coastal water bodies, while Phosphorus levels are too high in 28% of rivers and 36% of lakes. Addressing water quality issues is one of the top priorities for the agricultural sector and this is being reflected from a policy perspective and in the new ‘Green Architecture’ of the CAP where environmental sustainability is front and centre of an array of schemes. It is important for farmers to be aware of the importance of water quality as heightened regulations and restrictions may ensue down the line if water quality does not improve.

Nutrient enrichment or ‘eutrophication’ has a significant impact on water quality. When nutrients (Nitrogen and Phosphorus) enter our water courses they promote the growth of algal blooms which reduce oxygen levels in water. This has major implications for aquatic life in waterbodies as oxygen availability is reduced due to the growth of algae and phytoplankton biomass, and spawning ground is also lost. It results in the decline of aquatic species that are sensitive to pollution and conversely an increase in species which are pollution tolerant. This process is a key indicator of water quality.

Nitrogen (N) losses typically occur in free draining, light soils as N does not bind tightly to soil. The application of more N than the growing plant can take up is a common cause of N loss to water. In this instance, rainfall causes excess N to be leached downwards through the soil, ending up in our groundwaters, streams and rivers.  

In the West of Ireland, the loss of Phosphorus (P) and sediment to waterbodies is having the greatest impact on water quality. P loss typically occurs on soils that have low permeability. These are ‘heavy’, poorly draining soils with high clay content and get quickly saturated with rainfall. When there is heavy rainfall on these saturated soils this leads to water lying on the soil surface. This in turns leads to overland flow of water, particularly on fields with slopes. The overland flow of water across fields brings with it P available to plants in soluble form from fertiliser application. It also washes off soil particles (sediment) that have P attached to them. The soluble P and soil particles can then be washed into waterbodies on the farm and subsequently into other localised waters, resulting in water quality decline. Land drainage and reclamation, drain unblocking, outwintering and drinking point access for cattle also contribute to P and sediment loss.

So what can farmers do I hear you ask? The following are some effective mitigation measures:

• Implement targeted Riparian Buffer Zones (RBZ) along watercourses. RBZ’S “break the pathway” of nutrient/sediment/herbicide loss from agricultural land to watercourses
• Targeted fertiliser application at optimum times – adhering to prohibited spreading periods and weather/ground conditions
• Have a Nutrient Management Plan for the farm – ensure nutrients are directed to fields most in need and application rates are correct
• Spread slurry with Low Emission Slurry Spreading (LESS) equipment – helps reduce losses and improves nutrient use efficiency
• Prevent livestock access to drains and streams by providing alternative drinking water sources
• Employ proper drain maintenance practices

Farmers should be aware that specific regulations are in place under Ireland’s Nitrates Action Programme for the protection of waterbodies from agricultural activity and these must be adhered too. Farming and water quality go hand in hand and it is paramount that we do our upmost to improve water quality. Every farm is different and so site specific land management advice is needed. Contact your local Teagasc office if you require any further information on mitigation measures, regulations or how to protect water quality on your farm.