Sixth
DISCOVER Conference on Food Animal Agriculture:
Nitrogen Losses to the Atmosphere
from Livestock and Poultry Operations
April
28-May 1, 2002
Abe
Martin Lodge in Brown County State Park
Nashville,
Indiana
Animal agriculture and agricultural engineering professionals came together to share ideas on the impact of volatile nitrogen emissions from livestock and poultry operations on air quality at the sixth DISCOVER Conference on Food Animal Agriculture. This DISCOVER Conference, held April 28-May 1, 2002 in Nashville, Indiana, was titled, "Nitrogen Losses to the Atmosphere from Livestock and Poultry Operations.” A panel of thirty-one invited speakers represented various regions of the US, as well as Canada, Denmark, Holland, Sweden, and the UK. Summaries of their presentations are available at http://www.adsa.org/discover/.
Livestock and poultry operations account for 60-80 % of the ammonia released to the atmosphere in the United States. Global ammonia emissions to the atmosphere in pre-industrial times was 30-40% of current amounts. As an indication of the growing concern over the impact of confined livestock and poultry operations on air quality, the EPA recently commissioned a study of air emissions from confined livestock and poultry operations by the National Academy of Sciences. The Academy’s interim report is available from the Academy Press at http://www.nap.edu/openbook/030908461X/html/2.html
At the DISCOVER Conference,
several key points were raised:
-
Volatilized ammonia
contributes to acid rain, combines with other nitrogen and sulfur pollutants to
form small air-borne particles that reduce air quality and threaten human
health, and results in nitrogen deposition and over-fertilization of fragile
ecosystems. In southern California, for
example, deposition rates of close to 50 lbs of nitrogen per acre have been
measured, resulting in increased bio-mass of exotic grasses at the expense of
native shrubs and possible increase in the incidence and severity of grass
fires.
-
In addition to ammonia,
a variable portion of the nitrogen excreted by animals (about 2%) is emitted to
the atmosphere as nitrous oxide. Nitrous oxide is a potent greenhouse gas,
approximately 310 times as effective as carbon dioxide (per unit weight) in its
global warming effects, and is the largest component of green house gases
emitted by livestock.
-
The conference looked at
a variety of effective ways to reduce volatile emissions from manure, including
reducing dietary protein. It is important to note, the practice may be more
difficult for some species than others, resulting in reduced growth and
increased costs. Producers need to research their options and know the outcomes
before making such adjustments to their ration formulations.
-
Researchers also
reported looking at animal and manure storage facilities when working to reduce
volatile nitrogen emissions. While some measures are difficult to justify from
a cost perspective, many approaches do exist. Additionally, field application
methods can effectively reduce nitrogen losses. Significant loss (about 50%) of
ammonia nitrogen can occur with splash plate application of slurry manure to
the soil surface. Alternatively, banding of manure with a sleighfoot is a low-cost
way to apply manure uniformly in all weather and can reduce ammonia emissions
by 45-50% and odor by 36% when compared to splash plate application.
- It is important for the animal industry to obtain better quantitative information on volatile nitrogen emissions (ammonia and nitrous oxide) from animal facilities and manure storage, and then to proceed with reduction of emissions utilizing best management practices and application of existing and new technologies.
A total of 120 individuals attended the three-day conference, conducted in a retreat-type setting with sessions held each morning, early afternoon and evening. Time was set aside each afternoon for elaboration, further discussion and recreation.