Plan for Ammonia Reduction?

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Plan for Ammonia Reduction?

Postby david » Sun Dec 10, 2006 10:54 pm

Plan for Ammonia Reduction?
by
Dr. Jessica G. Davis
Professor, Soil and Crop Sciences
Colorado State University
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Ammonia used to be considered only as a nuisance odor emitted by dairies and other
livestock operations. Now, ammonia is known to react with atmospheric nitric and
sulfuric acids to form fine particulate matter (known as PM2.5), which is a major
contributor to smog production. This fine particulate matter is of concern because it has
numerous important human health effects. It can penetrate deep into the lung tissue,
contributing to asthma, bronchitis, and other lung diseases, and has also been linked to
heart attacks and strokes. In addition, when ammonia is converted to PM2.5 it becomes
more mobile and can travel longer distances to affect populations and/or be re-deposited
to the ground through rainfall or dry deposition. Nitrogen deposition in Rocky Mountain
National Park has resulted in increased soil and water N levels, which can cause changes
in plant species and eutrophication. So ammonia is not just a nuisance anymore; it can
have serious human health and mountain ecosystem impacts,
Regulations concerning ammonia emissions are likely to be developed in the future..
There are practices that you can use to be pro-active and reduce ammonia emissions now,
and more are in development. If you use a combination of BMPs, dairies can reduce
ammonia emissions by 65-70% (Powell, 2006).
Best management practices (BMPs) can be utilized to reduce ammonia emissions. Since
the production facility, manure storage and treatment areas, and sites where manure is
applied to land are all major sources of ammonia emissions, ammonia BMPs should be
chosen in each of the areas of nutrition, production site management, manure storage and
treatment, and land application of manure.
Nutrition BMPs focus on precision feeding, the practice of providing the animals what
they need and no more. Overfeeding protein has been shown to increase ammonia
emissions from both monogastrics and ruminants, so take care to avoid this practice.
Analyzing feeds regularly is a useful BMP for precision feeding since feed contents are
quite variable. Phase feeding is a commonly used practice for meeting livestock nutrient
needs without exceeding them. By dividing the herd by growth stage and productivity,
more precise diets can be fed that meet animal needs while minimizing ammonia losses
to the air. These practices can also save you money! Experiments in Switzerland
(Kulling et al., 2001) found dramatic reductions (up to 76%) in ammonia emissions from
laboratory simulations of manure storage from dairy cows fed reduced protein in the diet.
The milk production of 68 lbs/d was maintained in the low protein diets by
supplementation of a commercially available ‘bypass methionine’. A recent study by
Misselbrook et al. (2005a) showed that reducing crude protein in dairy diets reduced
ammonia emissions when manure was applied to land. Lower crude protein diets
reduced urinary urea-N levels thus leading to less ammonia loss from land application.
Therefore, nutritional changes continue to reduce ammonia emissions during manure
storage and land application.
In pens, dust control BMPs will help to reduce ammonia loss by decreasing the airborne
PM2.5 potential. Frequent manure harvesting combined with pen moisture management
can be very effective in minimizing dust. Watering the pens, especially those areas with
low activity and low moisture, is an effective BMP. Another recent study compared
ammonia losses from dairies using different bedding types (Misselbrook and Powell,
2005). Sand bedding reduced ammonia loss by over 50% as compared to chopped corn
stalks and composted manure, and chopped straw and pine shavings had intermediate
ammonia losses.
BMPs for manure storage and treatment can also be helpful to reduce ammonia loss to
the air. Reducing storage time reduces N loss to the atmosphere by reducing the reaction
time. Covering manure stockpiles and lagoons, and keeping stockpiles dry also reduce N
emissions. Aerobic lagoons and anaerobic digesters are also known to conserve nitrogen.
The crust that sometimes forms naturally on dairy lagoons was recently measured to
reduce ammonia emissions by up to 50% (Misselbrook et al., 2005b). Bedding type
continues to have an impact if solid manures are composted; wood chip bedding results in
much lower nitrogen loss to the air than straw bedding during the composting process
(Hao et al., 2004).
When manure is applied to land, BMPs continue to play an important role in reducing
ammonia emissions. Incorporation of manure immediately after application is critical to
retaining nitrogen in the soil. Slurries should be injected and drop nozzles could be used
for sprinkler irrigation to reduce “air time” and minimize ammonia losses.
I don’t mean to alarm you with yet another concern, but ammonia emissions regulation is
likely. Decisions made now could ease your compliance later We’ll keep you up-to-date
so you can choose BMPs that are appropriate for your operation.
References
Hao et al., 2004. J. Environ. Qual. 33:37-44.
Kulling et al., 2001. J. Agric. Sci. Camb. 137:235-250.
Misselbrook et al., 2005a. J. Dairy Sci. 88:1765-1777.
Misselbrook and Powell, 2005. J. Dairy Sci. 88:4304-4312.
Misselbrook et al., 2005b. J. Environ. Qual. 34:411-419.
Powell, 2006. Proc. of the Airy Symposium. Visions for Animal Ag. and the Environ.
david
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