An EU opt-out for Irish farmers could expire at the end of the year without a new agreement.
The Nitrates Directive came into force in 1991. Its objective is to protect water quality from agricultural pollution and to promote the use of good farming practices.
But Ireland has always insisted that its wet climate made the limits set by the law impossible for farmers.
For that reason, Ireland has always been able to get an opt-out.
That allows Irish farmers to spread more manure on the land.
Under normal circumstances, farmers are not allowed to apply more than 170 kilograms of organic nitrogen per hectare per year on their land, however, with the derogation, that limit has been increased to 250 kilograms.
The current derogation is due to expire at the end of this year.
The government says it is in ongoing talks with the EU to try and get a new opt-out.
But calls for the EU to get tough on environmental law are getting stronger.
Ireland and the Netherlands are the last member states still to get the derogation.
It is believed that the Dutch will let theirs expire, meaning Ireland will become the last one.
The European Commission says in order to grant a further derogation Ireland will need to demonstrate the merits of such a scheme. And ensure it is in line with EU law.
Ireland will also need to convince a majority of member states to lend their support in a vote in a technical committee.