27 January 2023


Novel techniques that reduce ammonia levels in poultry litter could help livestock farmers meet new environmental targets.

A three-year Farming Connect trial at Wern Farm, near Welshpool, showed how introducing non-infective bacteria into sheds had dried out litter, made it easier to store and spread and significantly reduced the ammonia and odour levels.

Before the trial, farmer Osian Williams had to remove muck from the belts almost twice a week; if he didn’t, ammonia could peak to harmful levels and the belts could not cope with the weight of the heavy wet litter.

The trial involved spraying two sheds each housing 16,000 hens with a stabiliser manufactured by Pruex; this product contains non-infective bacteria and aims to dominate the bad bacteria in the shed.

It dried out the litter to such an extent that the frequency of muck removal could be extended to every 10-14 days, resulting in significant savings on labour and machinery costs, farmers were told during a recent Farming Connect webinar when the end of study results were published.

Natural Resources Wales (NRW) Senior Policy Adviser Jeremy Walters, who was among the speakers, said that with pressure on the poultry sector to reduce emissions new technologies like the Pruex system are likely to play an important role.

He described the project results as “very encouraging’’ and believed that innovations of this kind would help with ammonia reduction and the handling of manure and slurry going forward.

The next step is to quantify the results from this study, said Mr Walters, to ensure they can stand up to robust scrutiny.

Ammonia emissions have been steadily rising in Wales in recent years – more than half of the country experiences concentrations that are too high for some sensitive habitats.

“Novel techniques to reduce ammonia emissions are emerging and are welcomed by NRW,’’ said Mr Walters.

“We will endeavour to establish the appropriate emission factor or percentage reduction associated with each technique for use in modelling the impact of developments.’’

Evidence which NRW would require for it to take into account the reduction in ammonia by using novel techniques include a control operation running alongside within the same parameters and use of an appropriate measurement methodology backed by peer review. That emission measurement data would need to be properly recorded and traceable.

At Wern Farm, the efficacy of the system was noticeable when the sheds were mucked out.

Mr Williams said that previously, after mucking out, a 10-12 foot high heap might reduce by two third by the following day because moisture levels had forced it over a bigger area.

“It might now only come down one or two foot, if that,’’ said Mr Williams.

The quantity of muck that needs to be handled is greatly reduced and its nutrient value makes it a valuable soil conditioner, the webinar was told.

Another major gain is that the treated litter has little or no odour, said Pruex director Aled Davies.

“The whole process of drying out things to get preservation and less rotting is something we have known about for many, many years,’’ he said.

He drew similarities with the requirement for hay to be dry before storing to prevent spoilage and the use of salt to preserve pigmeat.

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