Reducing ammonia emissions in a poultry house — litter additives and aeration
Ammonia comes from the breakdown of uric acid in manure and is one of the biggest threats to bird welfare and the environment. It irritates the flock’s airways, lowers rearing results, and once it leaves the house it acidifies soil and water. We show how to cut emissions at the source: with dry litter and ventilation, manure aeration, litter acidifiers and smart feeding.
verifiedFrom the team that has organised work on poultry farms for years.
Ammonia (NH3) in a poultry house doesn’t come out of thin air — it forms in the litter. Poultry manure is rich in uric acid and undigested nitrogen, which bacteria and enzymes break down into ammonia. The wetter and warmer the litter, and the more alkaline its pH, the faster ammonia is released. So fighting emissions is first and foremost about controlling moisture, pH and nitrogen in the manure, and only then about exhausting the gas outside.
Why does ammonia harm birds and the environment?
For the flock, ammonia is an irritant. It damages the lining of the airways and the conjunctiva, opens the door to infection, lowers appetite and weight gain, and at high concentrations leads to footpad lesions and burns. Even a handful of ppm at bird level lowers rearing results. For the environment, ammonia is a gas that, once emitted, falls back with rain, acidifies soil and water, and contributes to particulate matter. Cutting emissions therefore means better welfare, better results and a smaller environmental footprint for the farm all at once.
How to lower ammonia emissions
The most effective approach combines several methods: dry litter, good ventilation, acidification and smart feeding. Each one strikes a different stage of how ammonia forms.
Dry litter and moisture control
Moisture is fuel for ammonia. Litter above roughly 30–35% moisture sharply increases its release. Leak-free drinkers, working drainage, good roof insulation and litter of the right depth and absorbency keep the manure dry. Dry, friable litter is the cheapest and most effective way to limit emissions.
Minimum ventilation and air exchange
Even the best litter needs moisture and gases removed. Minimum ventilation, matched to bird age and the weather, clears water vapour and ammonia before they build up, without chilling the flock. Managing relative humidity in the house indirectly keeps ammonia in check too.
Aeration and drying of the litter
Tilling and aerating the litter breaks up caking and speeds the evaporation of water from the top layer, where most ammonia forms. Under-litter air-blowing systems or periodic mixing of the surface layer keep the manure drier and better aerated, which limits the anaerobic breakdown that drives emissions.
Acidifiers and litter additives
Ammonia escapes more easily the more alkaline the litter pH is. Additives that lower pH — aluminium sulphate, sodium bisulphate or superphosphate — shift the balance so nitrogen stays bound as ammonium ion instead of escaping as gas. They are usually applied to clean litter before chicks are placed, and the effect is strongest in the first weeks of rearing.
Low-protein feeding and amino-acid balancing
The less undigested nitrogen reaches the manure, the less ammonia forms. Lowering crude protein in the feed while topping up with synthetic amino acids covers the birds’ needs and excretes less nitrogen. This is one of the most effective ways to cut emissions at the very source, before ammonia even forms in the litter.
Feed additives and nitrogen binding
Some feed additives reduce emissions indirectly: yucca extract (Yucca schidigera) binds ammonia and limits its release, while probiotics and feed acidifiers improve digestibility and gut pH. Used together with low-protein feeding, they support drier, lower-emission manure.
Cutting ammonia step by step
- 1
Start with drinkers and moisture
Check the drinking line for leaks, adjust the pressure and nipple height, and improve drainage and insulation. Wet litter under the drinking lines is the most common source of ammonia. Keeping the manure dry and friable gives the biggest effect at the lowest cost.
- 2
Set minimum ventilation
Match minimum ventilation to bird age and outdoor conditions so it removes moisture and gases without chilling the flock. Aim for stable relative humidity in the house — when it rises, so does the risk of ammonia emission. React to the season and stocking density.
- 3
Aerate and dry the litter
If caking appears, till the top layer of litter or use under-litter air-blowing if you have it. Breaking up the crust and aerating the top layer speeds water evaporation and limits the anaerobic breakdown that drives emissions.
- 4
Apply an acidifier before placement
Spread a pH-lowering additive on clean litter before chicks are placed, following the manufacturer’s dose. A lower pH keeps nitrogen bound during the critical first weeks, when chicks are most sensitive to ammonia. Record the type and dose of the product used.
- 5
Optimise feeding with a nutritionist
Together with your feed supplier or a nutritionist, lower crude protein and top up synthetic amino acids, and add yucca extract or probiotics if needed. Less undigested nitrogen in the manure means less ammonia before it even forms. Tailor the formula to the rearing phase.
- 6
Watch and record the results
Note litter condition, humidity, the additives used and how it feels at bird level, and if you use gas monitoring, set it against the changes you made. Keeping a record lets you see which actions actually lower emissions in your building, and repeat what works.
Frequently asked questions about reducing ammonia in a poultry house
Where does ammonia in a poultry house actually come from?add
From the manure. Birds excrete nitrogen mainly as uric acid, which bacteria and enzymes in the litter break down into ammonia. The process is sped up by moisture, heat and an alkaline litter pH. So ammonia isn’t “from the air” — it forms on the spot, in wet manure, and that is where it is most effectively limited.
Is reducing emissions the same as measuring ammonia with a sensor?add
No, they are two different things that complement each other. A gas sensor tells you how much ammonia is in the air at a given moment. Reduction is the set of actions that make less ammonia form in the first place: dry litter, ventilation, acidification and feeding. Measurement helps you judge whether those actions work, but on its own it does not lower the concentration.
How do litter acidifiers limit ammonia?add
Ammonia escapes more easily the higher (more alkaline) the litter pH is. Additives such as aluminium sulphate, sodium bisulphate or superphosphate lower the pH, so nitrogen stays bound as ammonium ion instead of being released as gas. They are applied to clean litter before placement, and the effect is strongest in the first weeks of rearing.
Won’t lowering protein in the feed harm the birds?add
No, if it is done sensibly. The idea is to lower crude protein while topping up with digestible amino acids, so the birds’ needs are still met. The birds then excrete less undigested nitrogen, so less ammonia forms in the manure. Formulas are best set with your feed supplier or a nutritionist and matched to the rearing phase.
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