The rules governing Nitrate Vulnerable Zones may be tightened up from July this year, the National Pig Association has learned.
It has warned that whole farm average manure loading rates could be lowered from 210kg N/ha to 170kg N/ha.
Most of the UK is covered by NVZ rules and non-compliance may jeopardise Single Farm Payment rates.
A closed period for slurry spreading on sandy and shallow soil currently applies between 1 Aug and 1 Jan.
It is proposed to extend this restriction to all soil types which will be phased in on clay type soils.
Under existing NVZ rules pig units must have storage capacity to exceed the present closed period of two months for grassland/three months for arable.
Under new proposals to extend the closed period restrictions units will have to have an additional storage capacity for slurry, but FYM can continue to be stockpiled on fields providing there is no risk of water pollution from run-off.
But if the rules were changed to include outdoor producers this would effectively signal the end of outdoor pig production.
Current stocking rates of 10 sows per acre would have to be cut to 3.5 sows/acre which would effectively treble outdoor pig rents and associated land management costs.
IPPC regulations will also require improvements to on-farm slurry and manure storage facilities from 2007.
Although IPPC rules will only apply to larger pig units with 750 plus sows/2,000 plus finishers, producers are warned that this threshold may be reduced in future years.