1945 Windbreaks: Natural Erosion Control - webapps8

WINDBREAKS
Before settlers arrived on the plains
of the midwest and west, prairie
grasses and wildflowers stretched as far
as the eye could see. In Minnesota,
more than one-third of the state,
JIM RUEN million acres, was covered with
prairie vegetation.
There was little wind erosion. Back
then, the prairie soil was disturbed
only by wildfires, roaming herds of
buffalo,
and the activities of prairie
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dogs and other wildlife. But then came
the western movement and the moldboard
plow. Before long, vast expanses
of prairie were replaced by corn and
wheat. Cattle and sheep often overgrazed
vegetation that was not plowed
under.
The importance of trees on the
open prairie was recognized as early as
1873 with passage of the Timber
Culture Act. This bill offered homesteaders
160 acres if they would plant
trees on 40 acres. The Act was repealed
less than two decades later, but
not before millions of trees had been
planted.
Meanwhile, taming of the wild
prairie continued. More land was converted
to crops so that, by the end of
the century, the frontier was virtually
closed.
Dirty Thirties. It didn't take long
before Americans began to pay the
price for destroying the prairie grasses
and flowers which had held the dry,
sandy soil in place. And the price was
high—the infamous dust bowl of the
1930s. Drought came to the prairies.
Older farmers still tell of dust clouds
hundreds of feet high, burying
machinery and fence lines in drifts of
soil. With farm prices at rock bottom
because of the depression, the drought
forced many farmers off the land.
The federal government declared
war on the devastating erosion by
establishing the Prairie States Forestry
Project in 1935. The project provided
money for the Work Progress Administration
(WPA) and the Civilian Conservation
Corps (CCC) to plant trees for
erosion control. From 1935 to 1942,
more than 200 million trees and
shrubs were planted from Texas to
Minnesota and from the Rocky Mountains
to the eastern border of
Nebraska. More than 238,000 acres
were planted to windbreaks.
These shelterbelts proved invaluable.
They broke the force of the
ever-present prairie wind, protecting
soil particles along with newly-planted
seed and young plants. The windbreaks
reduced evaporation from the
soil and trapped snow during winter,
saving moisture for the coming growing
season. They beautified the landscape
and improved living conditions
for humans, livestock, and wildlife.
But once again man is changing the
pattern of the prairie. With renewed
emphasis on expanded farm production,
higher land values and resulting
higher taxes, farmers are striving to get
the most from their acres. The recent
drought, for example, catalyzed a
boom in farmland irrigation on sandy
soils.
Today, many people fear that, as
irrigation grows, the windbreak will go
the way of the big bluestem and the
prairie conefiower. Many shelterbelts
are in the way of the sweep of center
pivot irrigation systems, and thus are
being wholly or partially removed.
Windbreak removal is not a serious
problem in Minnesota, but it is occurring
in the southern plains states
where snow retention is not a factor
)ANUA RY —FEBRUARY 1978 37

System developed in Nebraska (left) shows section of center pivots
and windbreaks. Trees are primarily red cedars six feet apart in two to
four rows. Right: Low-growing shrubs across diameter of quartersection
center pivot circle is being tried in North Dakota. Fifty-foot
Cottonwood, or northwest poplars, border outer edge of North
Dakota system. (Artwork courtesy of Irrigation Age magazine.)
and in areas where center pivot irrigation
is being installed.
To aid farmers in soil erosion control
under center pivot irrigation systems,
the SCS advises use of annual
row crops such as corn or the planting
of shrubs at intervals throughout the
field.
Few farmers are using shrubs because
of the expense and labor needed
to keep the plantings trimmed to a
height below the center pivot boom. If
a mechanical hedge row trimmer could
be developed, interest in shrubs would
increase greatly.
Irrigation is a relatively recent development
in Minnesota agriculture,
one which is growing rapidly. As of
last June, 387,000 acres were sprinkler
irrigated. It is estimated that at least
two-thirds of this acreage is under
center pivot systems.
"Five years ago, shelterbelts were
being torn out to accommodate center
pivots, but with no provision to replace
the trees," said Fred Bergsrud,
Irrigation Specialist at the University
of Minnesota. "Today farmers have
become more aware of the potential
problems. Ottertail County was the
first to notice a problem with wind
erosion. There and in similar areas in
Minnesota the SCS and the University
are working with farmers to find a
solution."
New Ordinance. Sherburne and
Benton counties, two rapidly ex-
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panding irrigation areas, have suffered
soil losses because of windbreak removal.
Benton County commissioners
have passed an ordinance controlling
removal of windbreaks, one of the few
such laws in the nation. It requires
farmers to develop alternative plans
for soil conservation before they can
remove a field windbreak. Kevin Adelman,
SCS technician for the two
counties, said the ordinance has cut
windbreak removal in half.
About 30 miles of windbreaks have
been removed in Benton and Sherburne
counties, mainly because of new
irrigation projects. But only two miles
have been replaced. William Held of
Rice has started to replace some of the
six miles of shelterbelt he removed,
planting trees on the perimeter of his
fields. (Windbreaks on the outside of a
field do not offer the protection of
single-row windbreaks every 600 feet.
However, SCS endorses their use in
combination with other soil conservation
methods.)
"Most farmers in the two counties
have begun a program of minimum
tillage or mulch tillage in an effort to
protect the soil," said Adelman. One
landowner, Joe Gottward of Rice,
moved part of his windbreak out of
the way of his center pivot system and
replanted the trees elsewhere. Other
farmers have attempted to replant, but
dry weather in 1975 and 1976 killed
the young trees. Farmers indicate that,
if they receive enough snow this winter,
they will try again next spring.
Many soil experts believe that windbreaks
not only will prevent wind
erosion on an irrigated field, but will
make the unit more efficient. Water
can be distributed better with less
evaporation if a windbreak adjoins the
pivot system.
Irrigation isn't the only cause of
windbreak removal. In the Red River
Valley, windbreaks of Siberian elm
planted about 15 years ago are now
dying. "The fungus has been isolated,
but it is a secondary cause of death,"
said Scottie Scholten, University of
Minnesota College of Forestry professor.
"The trees have been weakened
by annual crop spraying."
John Hultgren, SCS Woodland Conservationist
in Minnesota, agrees that
crop spray may damage windbreaks of
Siberian elm. "Monoculture is always a
problem," he said. "Siberian elm
looked like the perfect tree, so that
was all that was planted. Today we
encourage a variety of trees in a
shelterbelt, such as a mixture of Siberian
elm, green ash, and cottonwood.
This decreases the likelihood of
disease and insect infestation as well as
the chance of crop spray wiping out
the entire shelterbelt."
The SCS, U.S. Forest Service Extension
Service, and the University of
Minnesota Experiment Stations are
constantly searching for new seedstock
and alternative species to use in field
windbreaks. "We are now looking at a
seed source which will give us a ponderosa
pine with more upright
branches for better snow distribution
across the field," said Scholten. "This
)ANUA RY —FEBRUARY 1978 39

is an important tree in western Minnesota
because of its ability to grow well
in prairie soils."
Another problem faced by owners
of field windbreaks is the replacement
of dying or damaged trees. Old trees
which no longer provide adequate soil
protection may cause the farmer to see
complete removal of the windbreak as
his only option. But there are others.
Replacing all or part of the tree line
can be done over a period of time by:
1) interspersing old trees with young;
2) beginning a second row of young
trees behind a mature row; 3) cutting
down the original growth so it will
grow back from the stumps. "Many
hardwood (deciduous) trees and
shrubs will send out sprouts from the
stump," advises Hultgren. "Simply
choose the straightest or healthiest
looking stem and trim away the rest.
Such regrowth can quickly replace the
trees cut down."
Inventory. The Soil Conservation
Service (SCS) is currently inventorying
shelterbelts in the nation's five major
windbreak states: Kansas, Nebraska,
Oklahoma, and North and South
Dakota. The nine-month study is in
response to a 1975 General
Accounting Office (GAO) report calling
for action to discourage removal of
windbreaks in the Great Plains. Using
aerial photographs, the study is accumulating
up-to-date information on
the number of field windbreaks in the
region, number removed during recent
years, and reasons for their removal.
William Lloyd, Chief Forester for
the SCS (Washington, D.C.), believes
that too much emphasis has been
placed on just the erosion control
benefit of windbreaks. "With the introduction
of minimum tillage, annual
grasses, stripcropping, and other forms
of intensive soil management, windbreaks
are no longer a necessity for
short term erosion control," he said.
"Instead, the biggest losers when shelterbelts
are removed are wildlife habitat
and recreational opportunities.
"The problem is," he continued,
"there is no economic incentive to
cause the farmer to use the land for
shelterbelts when he could use it for
cash crops."
Fortunately, Minnesota is one of
the leading states in planting trees for
field and farmstead windbreaks. In
1976, landowners planted nearly onehalf
million trees for field windbreaks,
offering more than 288 miles of protection.
This increased to 396 miles of
windbreaks planted in 1977, despite
advances in irrigation. This is encouraging
proof that windbreaks are
not a thing of the past, at least in
Minnesota. Interest in the many benefits
of windbreaks remains high and
their continued existence appears certain.
•
Jim Ruen is an Editorial Assistant for
the USDA Soil Conservation Service
in St. Paul.
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