Poultry Litter

What can be used as a poultry litter amendment?

By Tina Jensen Augustine

Poultry litter, a mix of manure, feathers, bedding, spilled water and feed, is commonly known to be high in nitrogen and is also a significant source of ammonia emissions. As uric acid and organic nitrogen in the litter break down, ammonia is released into the air, or volatilized. Volatilized ammonia not only has a strong, distinctive odor, but it can also be detrimental to the health of the poultry, causing eye and lung irritation and increasing susceptibility to respiratory disease. Ammonia emissions from poultry litter can also create atmospheric particulate matter, which can be detrimental to the environment. 

In order to reduce ammonia volatilization from poultry litter, operators often apply amendments to help control emissions and maintain better living conditions for the birds. Litter amendments function by a variety of methods to reduce ammonia emissions, such as inhibiting the release of ammonia by reducing litter moisture levels, or by scavenging gaseous ammonia that has already been emitted. The use of some litter amendments will also increase the level of nitrogen in the litter, making it more valuable as a fertilizer. Some amendments have also been observed to lower pathogen levels, making it safer to subsequently use the litter as fertilizer on food crops. 

Currently there are no synthetic litter amendments approved for use in organic livestock production. Several nonsynthetic materials can be used, and a number of OMRI Listed® products are marketed for this use. The substances include clay-based adsorbents such as naturally-occurring zeolite, diatomaceous earth, and montmorillonite, which function by absorbing ammonia onto the clay surfaces. Peat moss can also adsorb 2.5 times its weight in ammonia, and 20 times its weight in water. 

The most common litter amendments used in the conventional poultry industry are acidifying agents, and the predominant forms are synthetic. These amendments function by lowering the pH of litter, inhibiting the bacteria that transform manure nitrogen into ammonia. Aluminum sulfate, sodium bisulfate, and acid-activated bentonite are three such amendments and have been petitioned for addition to the National List for use as poultry litter treatments in the past. These materials reduce litter pH and bind ammonia. Aluminum sulfate, or alum, also binds phosphorus, reducing soluble phosphorus in litter fertilizer. The National Organic Standards Board (NOSB) voted to classify these materials as synthetic and rejected a motion to allow them in organic livestock production at the Fall 2016 meeting. 

1. Adsorb refers to binding to the surface rather than being absorbed.

Revised and updated in November 2018 by OMRI Technical Director Doug Currier. This article was originally published in the Spring 2016 edition of the OMRI Materials Review newsletter.