Drs C.W. Ritz, B.D. Fairchild, A.S. Tasistro and D.E. Kissel of the University of Georgia have evaluated surface-applied char on ammonia volatilisation from broiler litter in experiments supported by the US Poultry & Egg Association.

Ammonia (NH₃) can have detrimental effects on poultry live production performance, animal health and welfare, worker health, and the environment, they explain. Bird performance and health can be affected by both respiratory disease challenge and physical damage due to increased ammonia concentration. Poultry farmers have historically used ventilation to reduce the effects of ammonia inside the chicken house. However, expelled air transfers ammonia to the external environment adding to the problems caused by dust and odour, which can lead to neighbours' complaints and legal actions.

Litter treatments have been developed to help control ammonia release from litter, and have been used extensively by the poultry industry. They are applied prior to chick arrival and are a critical part of maintaining proper air quality during the brooding period when ventilation rates are at their lowest.

While litter treatments can be effective in controlling ammonia emissions, their overall use has met with varying levels of success. Carbon in its many forms has been used for years in water and air filtration systems. Chars can be manipulated to make them valuable environmental tools, such as the adsorption of ammonia on their surfaces. Biomass materials such as peanut hulls or tree clippings are available in Georgia in large amounts and could be used as raw materials for producing chars.

The purpose of this study was to evaluate the effectiveness of char and active carbon on reducing ammonia volatilisation from poultry litter when used as a surfaced-applied litter treatment.

Char was produced by pyrolysing peanut hulls at 752°F for 30 minutes. The peanut hull char (pH 9.2) and two acidified chars (53 per cent sulphuric acid; pH 2.0) made from pine chips and coconut husks were applied at rates of 50 and 150lb per 1,000 square feet to the floor of pens containing broilers at commercial density (0.75 square feet per bird). A second 150lb treatment was split into two 75-lb applications to determine if splitting the application of the amendment into one application at the start of the brooding and another half-way through the grow-out could improve its efficacy.

Ritz and co-workers found that the addition of peanut hull char did not reduce ammonia levels in the air compared to the untreated pine shavings bedding material. However, the addition of acidified chars applied at the 150lb per 1,000 square feet rate significantly reduced overall ammonia release compared to the untreated control and peanut hull char treatments.

The reduction in ammonia from the acidified char treatment is most likely due to a combination of litter pH reduction from the acid application and ammonia reaction with the sulphuric acid in the acidified char. Bird performance was not influenced by the litter treatments.

Further investigation into the use of carbon products for ammonia control in poultry houses is warranted.

October 2010