Use of alum to inhibit ammonia volatilization and to decrease phosphorous solubility in poultry litter

#The present invention relates to a method for inhibiting ammonia volatilization in poultry litter. The present invention further relates to a method for reducing phosphorus solubility in poultry litter.

#One of the major problems encountered in raising chickens, turkeys or laying hens under confined conditions is ammonia volatilization, the production of excessive levels of ammonia gas (NH.sub.3). As volatilization occurs, ammonia levels can reach as high as 100-200 ppm in poultry houses. For over 30 years, researchers have shown that excessive ammonia buildup in poultry rearing facilities adversely affects both poultry and farm workers. Scarborough (Delaware Agric. Exp. Stn. Prog. Rep., NE8, 1957) and Valentine (Br. Poultry Sci. 5:149-159, 1964) both observed ammonia levels in the 60 to 70 ppm range in the atmosphere of poultry houses. Ammonia levels reaching as high as 100 ppm in commercial poultry houses have also been reported (Anderson et al., Poult. Sci. 43: 305-318 (1964)).

#Anderson et al. demonstrated that when chickens, turkeys, guinea pigs, or mice were exposed continuously to 20 ppm ammonia, gross or histopathological signs of damage to the respiratory tract occurred after six weeks (Avian Dis. 8:369-379, 1964). They also found that chicks exposed to 20 ppm ammonia for 72 hours were much more susceptible to Newcastle Disease than controls reared in ammonia-free environments. Although all of the chickens had been exposed to the Newcastle Disease virus, only 40% of the chickens in the ammonia-free environment were infected, whereas 100% of the chicks were infected when exposed to ammonia. They indicated that these results may have been due to damage to the mucous lining of the respiratory tract.

#FIG. 1 illustrates cumulative ammonia volatilization (g nitrogen (N)/kg litter) from poultry litter with and without MLT amendments as a function of time (days). Plot A represents 10 g MLT. Plot B represents 20 g MLT. Plot C represents the control or unamended litter.

#FIG. 2 illustrates cumulative ammonia volatilization (g N/kg litter) from poultry litter with and without calcium hydroxide amendments as a function of time (days). Plot A represents 50 g Ca(OH).sub.2. Plot B represents 25 g Ca(OH).sub.2. Plot C represents the control or unamended litter.

#FIG. 3 illustrates cumulative ammonia volatilization (g N/kg litter) from poultry litter with and without ferrous sulfate amendments as a function of time (days). Plot A represents 200 g FeSO.sub.4. Plot B represents 100 g FeSO.sub.4. Plot C represents the control or unamended litter.

#The present invention provides a method for treating poultry litter, which inhibits ammonia volatilization from the litter and reduces soluble phosphorus levels in the litter. The method involves the addition of alum to poultry litter. Alum is an aluminum sulfate compound having the composition Al.sub.2 (SO.sub.4).sub.3 .multidot.nH.sub.2 O, with n varying from approximately 14-18 molecules of water due to the varying degree of hydration in alum. Since poultry litter is highly variable in composition, the quantity of alum needed to arrest volatilization also varies. However, the amount of alum necessary to inhibit the buildup of atmospheric ammonia in poultry rearing facilities is the amount sufficient to maintain the litter pH at values low enough to inhibit ammonia volatilization. In this regard, alum is applied to the litter in an amount equivalent to approximately 5-25% of the litter weight on a dry weight basis. For example, 130 grams of alum would be applied per kilogram of litter. During a normal growout, 20,000 chickens will generate 20 tons of moist litter (16 tons dry). Therefore, 2 tons of alum would be required per poultry house after each growout.

#Preferably, alum should be applied to the top of the litter and thoroughly mixed in with a mechanical mixer such as a power-tiller. Alum applications to litter also greatly reduced nitrogen loss in the litter, thereby further enhancing the value of this treated poultry litter as a fertilizer source. Ferrous sulfate was also found to dramatically reduce ammonia volatilization in litter.

#Studies revealed that in addition to aluminum compounds like alum, calcium and iron compounds when added to poultry litter, precipitate the phosphorus in the litter, resulting in a reduction of water soluble phosphorus levels by as much as 99%. In this regard, water soluble phosphorus levels in poultry litter were reduced from over 2,000 mg phosphorus kg.sup.-1 litter to less than 1 mg phosphorus kg.sup.-1 litter with the addition of alum, quick lime, slaked lime, ferrous chloride, ferric chloride, ferrous sulfate and ferric sulfate under favorable pH conditions. To achieve a reduction in the soluble phosphorus levels in litter, alum, calcium, and iron compounds were applied to litter in an amount equivalent to having a mole ratio of the metal to phosphorus of approximately 0.5:1 to 2.5:1. These results along with actual field application studies suggest that treating litter prior to field application with these compounds could significantly reduce the amount of soluble phosphorus in runoff from litter-amended pastures and increase forage yields.