|Powell, J Mark|
Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2005
Publication Date: 10/15/2005
Citation: Misslebrook, T.H., Powell, J.M. 2005. Influence of bedding material on ammonia emissions from cattle excreta. Journal of Dairy Science. 88:4304-4312. Interpretive Summary: Dairy cattle barns are major sources of ammonia emissions to the atmosphere, and previous research has shown that the bedding material used can influence the magnitude of these emissions. This laboratory study showed that the physical characteristics (urine absorbance capacity, bulk density) of bedding materials are of more importance than their chemical characteristics (pH, cation exchange capacity, carbon to nitrogen ratio) in determining ammonia emissions from applied urine and feces. Recycled manure solids were the most absorbent of the bedding types and sand the least. Ammonia emissions from urine-soaked beddings over 48 h were not different between bedding types. When urine was applied to dry bedding, ammonia emissions over 48 h were significantly lower from sand (23% of applied urine N), followed by pine shavings (42% of applied urine N), than from the other bedding types (mean 63%). These results indicate that selection of bedding may be based not only on cow comfort and health, but also on their ability to reduce ammonia emissions.
Technical Abstract: Dairy cattle barns are a major source of ammonia (NH3) emissions to the atmosphere. Previous studies have shown that the bedding material used in the barn can influence the magnitude of NH3 emissions but little is known about which bedding characteristics are important in this respect. The aims of this study were to assess, at a laboratory scale, the relative importance of the chemical (pH, cation exchange capacity (CEC), C:N ratio) and physical (urine absorbance capacity, bulk density) characteristics of 5 bedding materials (chopped wheat straw, sand, pine shavings, chopped newspaper, chopped cornstalks and recycled manure solids) on NH3 emissions from dairy cattle urine. Recycled manure solids were the most absorbent of the bedding types (4.2 g urine per g bedding) and sand the least (0.3 g urine per g bedding). When beddings were soaked in urine to their absorbance capacities, NH3 emissions over 48 h (expressed as a proportion of the urine N absorbed) were not significantly different between bedding types, despite differences in bedding pH, CEC and C:N ratio. When equal volumes of urine were applied to equal depths of dry bedding, NH3 emissions over 48 h were significantly lower from sand (23% of applied urine N), followed by pine shavings (42% of applied urine N), than from the other bedding types (mean 63% of applied urine N). Differences in the chemical characteristics of the beddings did not explain differences in emission; NH3 emissions increased linearly with CEC contrary to expectations and there was no significant relationship with bedding pH. The physical characteristics of bedding materials were of more importance with NH3 emissions increasing linearly with absorbance capacity and decreasing as the bulk density of the packed beddings increased.