The Rural Voice, 2004-01, Page 24Taking shelter
Shelterbelts of trees and shrubs can help reduce odour complaints in livestock
operations, agroforestrg specialist Todd Leutg sags
Story by Keith Roulston
Illustrations supplied by Todd Leuty
ural cynics sometimes say
R
people smell with their eyes
when it comes to new Targe
farm buildings but planting trees
around buildings can do more than
just screen out the offending
building, says Todd Leuty,'
agroforestry specialist with Ontario
Ministry of Agriculture and Food.
Certainly planting trees around a
new barn can
eventually help
screen off the barn
from the sight of
those who
automatically
associate new barns
with strong manure
smells, but the trees
can go farther in
eradicating the
problem. Leuty told
a recent nutrient
management
conference in
Shakespeare. They
help reduce the
odour problem in
five ways, he says:
1. They can help
dilute and disperse
the smell coming
from barns.
2. They can help
deposit dust and
particles much like
a windbreak causes
snowdrifts.
3. They can collect
and store the
chemical
constituents of the
odour within the
tree wood.
4. The trees can
physically intercept
odour particles like
dust and aerosols.
5. And the visual
barrier can make both the barn and
the fields on which you spread your
manure more visually appealing.
Properly designed shelterbelts do
reduce odour, Leuty says. They
disturb moving air masses and help
create the wind effect that helps meet
the farmer's needs.
A shelterbelt on the windward
side of a barn pushes the wind up and
No Shelterbelts
over the trees and barn. The
shelterbelt creates a "quiet zone" of
air downwind that measures a
distance of eight to 10 times the
height of the tree row downwind
from the trees. and an additional
moderation of wind speeds for a
distance measuring 10 to 25 times
their tree height. Livestock barns and
manure storage area are best located
in the quiet zone
just downwind of
the shelterbelt.
Odours emitted
from the barn or
manure pit tend to
travel along the
ground as a plume
with air movement,
especially during
atmospheric
inversions. By
disturbing the wind
pattern, shelterbelts
have the ability to
Odour plume travels along the gr
- Full strength smell
- Maximum neighbour complain
ound
is
Trees create an obstacle
Faster turbulent clean air
Calm breeze
-�.��► Less odour
100 feet
The top illustration shows what happens when there are no trees sheltering a
barn. The illustration above shows how a shelterbelt disrupts the winds.
20 THE RURAL VOICE
lift some of the
odour plume into
the lower
atmosphere where
the winds aloft mix
and dilute the
odour. The most
dilution occurs
above and
downwind from the
quiet zone, created
by the action of
wind passing over
the shelterbelt.
Beyond the quiet
zone, more fresh air
and less odorous air
returns to the
ground, reducing
the movement of
livestock odours off
site.
The proper design
forces turbulent