Defra’s new emission factors deliver welcome boost to pig industry
9th Dec 2024 / By Alistair Driver
Defra has published new ammonia emission factors for pig and poultry farms, which, according to AHDB’s Zanita Markham, will save British pig farmers more than £15m.
The updated figures follow AHDB’s multi-year ammonia monitoring trial, the findings of which have been incorporated into the Environment Agency’s (EA) updated ammonia emission factors.
They show a significant reduction on previous emissions factors, in some cases by half, which will help farmers who require an environmental permit and should also support planning applications.
All permitted producers – indoor pig units with more than 2,000 pigs above 30kg, or more than 750 sows – are required to meet the best available technique (BAT) associated emission levels (AELs), which are benchmark levels for farms to achieve. A new set of BAT conclusions, published in 2017, included limits on emission levels for ammonia, nitrogen and phosphorus.
Zanita, AHDB’s projects and engagements relationships manager (pork), said it was clear that by using the older emission factors (EFs), which were very outdated and not representative of current production, that UK pig farms were not going to reach compliance with the BAT AELs.
“But the AHDB project provided updated data on the performance of different types of modern pig housing and evidence to support revising the ammonia emission factors for UK pig housing. The data we gathered showed emissions on pig farms today are generally much lower, and in some cases have halved,” she said.
With the changes to EFs, most units are already compliant with the new target emissions levels,” she added. “For example, factors for finishers on straw are now an average of 1.88kg of ammonia per animal place per year compared with the outdated figure of 2.97kg.”
Ammonia is released to the atmosphere from slurries and nitrogen fertilisers. Housing, handling, storage and spreading of slurry all contribute to the spread of any pollution.
When the gas reacts with other compounds it forms secondary particulate matter, which can affect human health. It also contributes to smog in urban areas, as well as causing damage to sensitive habitats such as lakes, heaths and woodlands.
NPA chief executive Lizzie Wilson said: “This is a very welcome revision of the outdated emissions factors, which paint a much more realistic picture of the environmental footprint of pig farms across the different stages and systems.
“This has been a real collaborative effort and a long time coming. The considerable amount of work that has gone into the new figures will benefit the wider pig industry.”