Submitted to: American Society of Agronomy
Publication Type: Abstract Only
Publication Acceptance Date: July 15, 2004
Publication Date: October 31, 2004
Citation: Misselbrook, T.H., Powell, J.M., Broderick, G.A., Grabber, J.H. 2004. Reducing ammonia losses from dairy manure application to soil through dietary manipulation [abstract]. American Society of Agronomy. Paper No. 4522. Technical Abstract: Dairy production represents a major source of ammonia (NH3) emission from agriculture, about which there are increasing concerns because of environmental impacts. Much of the NH3 emission occurs following land spreading of manures. Modifying diets to reduce urea excretion represents one potential abatement strategy, which would reduce NH3 emissions from manure, including after land spreading. This study assessed the effect of manipulating dietary crude protein (CP) content or tannin levels in forage legumes on NH3 emissions from fresh and stored slurries. A system of small laboratory chambers was used to measure NH3 emissions following slurry applications to a silty loam soil. The high CP diet resulted in a slurry with a higher total N and ammoniacal N content and higher pH. Cumulative NH3 emissions were greater from the high CP treatment both in absolute terms and when expressed as a proportion of the slurry ammoniacal N applied. A diet formulated with a high tannin forage resulted in a slurry with similar total N levels as a low tannin forage, but a lower ammoniacal N content and a lower pH. Cumulative NH3 emissions from manure derived from diets based on high tannin forages were lower than other diets in absolute terms and when expressed as a proportion of the total N applied, but a similar proportion of the ammoniacal N applied was lost from all manures.