This Code of Good Practice has been prepared to maintain optimum production of quality food while at the same time minimising nutrient loss through leaching, runof or losses to air, and thereby prevent any avoidable rise in nitrate and phosphate levels in water.
There are 2 excellent reasons for so doing:
1. Plant nutrients are valuable.
1 tonne of nutrient N costs over £400.
1 tonne of nutrient P costs over £800.
1 tonne of nutrient K costs over £300.
2. Our waterways must be protected from nutrient enrichment. The EC Water Quality Directive requires that drinking water must not contain more than 50mg/l. nitrate (11.3mg/l, expressed as N ) and establishes a guideline level of 25mg/l. of Nitrate. Phosphorus and nitrogen in water may give rise to eutrophication. Nutrient enrichment of the water leads to an overgrowth of algae and aquatic plants which in turn causes a depletion of oxygen in the water, leaving it unable to sustain other forms of life. If animal manure finds its way into water it increaes B.O.D. levels and depletes oxygen supply. Resultant harmful bacterial contamination of the water is a health hazard. Nitrate and phosphates are released, increasing vegetative growth and leading to further eutrophication.
The favourable position in Ireland
There are water quality problems in several parts of the European Union. Overall in Ireland the quality of our water is good. It is important that we now redouble our efforts to ensure that our existing high water quality is preserved while improving the quality of our polluted waters.