High Plains Journal, KS
06-25-07
Proper odor management reduces problems for pork producers
By Jennifer Bremer
Most people think of odor when hogs and hog buildings are involved, but with
proper management techniques the odor nuisance can be reduced or even
eliminated.
Iowa State University professor of agriculture and biosystems engineering,
Jay Harmon, told attendees at the World Pork Expo that odor is caused by three
main sources--buildings, manure storage and land application.
"The odor from all of these sources can be controlled with proper management,"
said Harmon.
He has developed a list of ten steps to managing odor on the farm:
Siting of facilities is absolutely the most important aspect of managing odors.
Harmon suggested using a community assessment model that looks at the site in
relation to what is around it.
He said it is not necessarily the facility itself, but rather the residents and other
receptors around the facility that are affected by the odor.
Producers must look at the distance and exposure angle of the odor in
relationship to these other receptors. Wind can be another major factor in how
the odor affects different receptors.
"Distance is not always equal in all directions," he explained. "If the chosen site
will have a high impact on other receptors for years to come, it is easier to move
the site before the building is built and causes problems."
Injecting manure can reduce odors over broadcasting by 50 to 75 percent. This is
doubly important because of distance to neighbors, wind direction, terrain and air
drainage, and exposure angle.
"Targeted crop land may be near neighbors and application often occurs during
warm weather when neighbors' outdoor activities could be impacted by odors.
Sweep selection makes a big difference," he said.
Dietary manipulation can affect odor also and if utilized effectively can reduce
odors by up to 25 percent.
"The beauty of this approach is that it is nearly instantaneous. The disadvantage
is that feed cost will influence the cost effectiveness," he said.
Covering of outdoor manure storage can reduce the odors from storage by 50 to
80 percent. The production facility will still be a source of odors, however.
Harmon said there are different options when it comes to the covering.
Permeable coverings could include straw on the surface, cornstalks or a
geotextile to reduce odor by 40 to 50 percent. The cost of these coverings is 10
to 25 cents per square foot.
Impermeable coverings can be used to trap the gases and reduce odor by 70 to
85 percent. The cost of these coverings can cost $1 to $1.40 per square foot.
Visual barriers and appeal play to the cliché "out of site out of mind."
"There is more truth to that expression than is given credit," said Harmon. "It is
hard to quantify the impact but visual barriers and a well-kept farm site makes a
big impression on the nose."
Well-kept sites get fewer complaints and reflect on the overall management of
the site.
Pit ventilation tends to accelerate the transmission of odors because it pulls air
across the pit surface. He said to consider designing buildings without pit fans.
Proper inlet selection and placement becomes very important in this case.
"Pit odor contributes to more than half the total odor load during critical periods,"
Harmon said. "There is limited benefit to indoor air quality when designing pits."
Biofilters can be 70 percent or more effective in reducing odors. However, they
do take up space and must be diligently managed and designed as to not
negatively impact the ventilation system.
He said biofilters need to be designed to work with typical ventilation fans.
Management and particularly moisture is critical. He pointed out that bacteria
establishment in a biofilter can take about one month; therefore producers should
plan ahead if they will be adding a biofilter to their system.
Vegetative Environmental Buffers are multiple tree lines intended to stir the air
upward and break up the odor plume.
"It is difficult to quantify the impact on odor transmission, but 10 percent it a
modest estimate. They also add to the aesthetics and visual barrier of the site
giving an added bonus," he said.
Chimneys on ventilation fans, if properly designed, can be somewhat effective in
dispersing the odor plume. This promotes mixing of air. While it can be relatively
low cost, Harmon said that height is a very important factor to consider for
effectiveness.
"They are relatively inexpensive, but can add to the image of a 'factory farm,'" he
said.
Other methods to reduce odor include scrubbers, additives, aeration and
anaerobic digestion with varying levels of success. Additives can be most
effective to dilute a system. Aeration works well, but is more expensive. Barriers
help remove dust. Digestion is 50 to 80 percent effective, but it is a bigger
investment.
Harmon stressed that it is important to come up with simple solutions first.
"When planning new facility siting, be careful to consider all these factors in order
to reduce odor," he said. "It will help make raising hogs easier for you in the
future."
Jennifer Bremer can be reached by phone at 641-938-2342 or by e-mail at
jbremermaj@hotmail.com.