Jaime DeRosier lets plants perform much of the weed management for
his small grain and row crops. Allelopathic plants, such as buckwheat
and rye, produce and release natural compounds that destroy many kinds
of weeds or suppress their germination. Buckwheat and rye also form
dense canopies that shade out weeds and have the added benefit of extracting
phosphorus from the soil and converting it to compounds usable by crop
plants. Hairy vetch enriches the soil with nitrogen and produces
a dense, weed suppressing canopy. By using this trio of plants as
cover crops in his rotation and incorporating them into his soil, DeRosier
has been able to farm an increasing number of acres without the use of
synthetic inputs.
DeRosier's family has farmed in the Red Lake County area of northern
Minnesota for over a hundred years. During the 1980s, as DeRosier
farmed 200 acres in a conventional manner, he became concerned the high
cost of chemicals contributed significantly to the failure of many farms.
Studying organic methods and talking to older farmers with experience prior
to major dependence on chemicals, he became convinced it is possible to
farm successfully and profitably without the use of synthetic chemicals.
Through several years of experimentation and adaptation of organic practices
to his farm, DeRosier proved he could produce good crop yields without
chemicals. His improved economy of production encouraged him to gradually
increase the number of acres he farms to about 1,500 acres, most of which
is certified organic. DeRosier now produces soybeans, corn, sunflowers,
and flax, in addition to hairy vetch, winter rye, and buckwheat.
He accomplishes this primarily with his own labor along with some assistance
from his father.
Experimental Approach and Results
Aided by Hans Kandel, a Red Lake County Extension Educator, DeRosier has
experimented with the conversion of CRP lands to organic crop production.
In the summer of 1996, DeRosier plowed, disked, and cultivated some sod-bound
CRP land containing quack grass, trefoil, timothy, and small trees.
He seeded the ground with twenty pounds per acre of hairy vetch and 35
pounds per acre of winter rye, drilling the seed about one and half inches
deep. The cost for seed was approximately twenty and a half dollars
per acre. The rye and vetch faired well over the winter until a severe
ice and snowstorm in April 1997, which was followed by a "five hundred
year" flood. After the flood receded, the vetch was found to have
been damaged, but the rye had survived reasonably well. On the ninth
of June, DeRosier incorporated the rye and vetch with a moldboard plow
and field cultivator. On the following day, he planted popcorn and
Glacier soybeans. Although he was not able to cultivate the soybeans
until they were a foot tall due to standing water, the field remained weed
free and needed cultivation only for aeration. He cultivated the
corn and beans twice before the canopy closed. At harvest, the soybean
field was still clean and yielded approximately 25 bushels per acre, which
is about average for the area, despite the severe cold weather and flooding
endured by the vetch and rye in the spring. The popcorn did not fair
as well. It did not mature before freeze-up, so it was combined the
following spring.
In the summer of 1997, DeRosier planted buckwheat on 150 acres and incorporated
it by disk prior to the setting of seed. On the first day of September,
he planted fifty pounds per acre of RYMN rye mixed with twenty pounds per
acre of inoculated Madison hairy vetch. The field looked healthy
the following spring. DeRosier set aside a thirty by one hundred
foot test plot on part of the 150 acres to observe the effects of rye and
vetch residue on a variety of crops in unmaintained subplots, each five
by thirty feet in size. On the test plot, he incorporated the rye
and vetch as green manure at a height of 8 to 10 inches using a tandem
disk. Due to rain, he disked again several days before planting,
allowing time for the plants to die but also compacting the soil.
The plot was not cultivated after planting. The test plot offered
poor growing conditions due to low fertility, soil compaction, and lack
of cultivation. The rest of the 150 acres of rye and vetch produced
a good harvest and remained free of weeds. The test plot yielded
the following results (DeRosier 1999, p. 33).
-
sugar beets failed due to weeds
-
barley and wheat did well, remaining weed free and standing until freeze-up
-
mustard stayed weed free but lodged prior to freeze-up
-
field peas did very well and stayed free of weeds until about a month after
normal harvest time
-
buckwheat did well, remained weed free and did not lodge until well after
the point it would normally be harvested
-
several soybean varieties produced good yields and stayed free of weeds
-
red kidney beans produced beans early but competed poorly with weeds and
showed white mold
-
sunflowers and corn yielded poorly due to poor drainage, low fertility,
and lack of cultivation
-
potatoes were destroyed by blight and beetles
-
hairy vetch by itself produced well but formed a mat due to lack of physical
support
Cover Crop Usage
Buckwheat, rye, and hairy vetch can be used as cover crops in a variety
of ways. For example, buckwheat can be grown during the summer and
then incorporated prior to setting of seed. Buckwheat germinates
and
grows sufficiently rapidly to permit growth and incorporation twice in
a summer. Alternatively, the first or second crop of buckwheat can
be harvested and the residue plowed in afterwards. Following the
buckwheat, winter rye and hairy vetch can be fall seeded. After the
rye and vetch are established, they can be grazed during the fall and again
in the spring. The rye and vetch can be incorporated in spring prior
to planting a crop, or a they can be cut for hay and later plowed under
in the summer as a green manure.
Vetch Blossoms
DeRosier says buckwheat can be interseeded with corn or sunflowers and
then cultivated when it reaches a height of eight to twelve inches into
the crop rows to nourish the crop and suppress weeds. Winter rye
can be mixed with the buckwheat when used in this fashion. Hairy
vetch can also be seeded into standing corn when it's about a foot high
or into sunflowers when they are about six to eight inches high.
Vetch can also be seeded into soybeans when their leaves begin to turn
yellow.
DeRosier complements his use of cover crops with mechanical tillage.
He particularly recommends the use of rotary hoes and harrows to kill germinating
weeds at the white root stage just within a day or two of planting a crop
and then after emergence of the crop. The first hoeing or harrowing
should be done at a high speed, but he recommends using a low speed for
subsequent passes after emergence. A field should not be hoed or
harrowed when the crop is just below, at, or just out of the soil surface.
(DeRosier 1998b, pp. 31-34).
Buckwheat
DeRosier says the allelopathic compounds released by buckwheat are effective
against quack and barnyard grasses and many broadleaf weeds, including
thistle and spurge. The degree of effectiveness depends on factors
such as the amount of residue incorporated as well as the timing of incorporation.
Generally, the more buckwheat residue incorporated, the greater the allelopathic
effect. Seeding buckwheat at a higher rate also helps it smother
weeds by generating a denser canopy. DeRosier reports, "Weeds seem
unable to grow even past the soil surface when there is buckwheat biomass
on and near the soil surface." (DeRosier 1998b, p. 7)
Bee on Buckwheat Blossoms
Buckwheat should be planted in loose ground when the soil temperature
is high. Phosphorus is extracted from the soil and stored in the
roots, stalks, and leaves during the first forty days of growth, up to
the onset of flowering. If harvesting a buckwheat seed crop is not
planned, the buckwheat should be incorporated prior to seed production
to avoid volunteer growth in later crops. DeRosier indicates disking
works well for incorporation. A period of time should be allowed
for initial decay of the incorporated plants prior to the planting of the
following crop. As the incorporated buckwheat decays, the phosphorus
and allelopathic compounds will be released.
When growing buckwheat for seed, DeRosier times his planting for the
latter half of May so that flowering and setting of seed are most likely
to occur under the cool, moist conditions needed for those stages.
Buckwheat seed does not all mature at the same time, and, depending on
growing conditions, some seed hulls may be empty and rather flat.
DeRosier swathes the buckwheat when the bottom third of the plants are
black and the top section brown. At this stage, there will still
be some green seed on top as well as some flowers remaining. After
drying, the windrows should be combined slowly with an open cylinder to
avoid cracking the seed. The wind should be set high enough to blow
out all flat, empty seed.
Winter Rye
DeRosier says winter rye will smother most weeds and its allelopathic compounds
are particularly effective against weeds with small seeds. In addition
to scavenging phosphorus, rye effectively recycles nitrogen and other nutrients.
So interseeding rye with corn can recover much nitrogen that would otherwise
be lost to leaching and make it available to succeeding crops. Like
buckwheat, rye releases its nutrients and allelopathic compounds as it
decays. However, it decays somewhat more slowly than buckwheat.
DeRosier says rye is particularly beneficial when planted with hairy vetch
because the stalks help support the vetch plants and seed and aid the bees
in pollinating the vetch. The physical support provided by the rye
helps prevent matting of the vetch.
DeRosier seeds his winter rye between mid August and mid September in
northern Minnesota. He seeds at a rate of fifty pounds per acre for
a cover or one hundred pounds per acre if he plans to harvest the seed.
He advises using one hundred fifty pounds per acre if frost seeding and
planning to harvest the grain. When rye is planted for use as a green
manure, DeRosier recommends incorporating it into the soil when the rye
reaches a height of about six inches. If left until it is ten or
more inches high, the rye will need to be incorporated with a plow.
The rye should be incorporated into the top four inches of the soil, since
that is where weeds germinate. This shallow incorporation should
result in a trashy look. DeRosier harvests his rye crop at about
the same time as winter wheat but earlier than barley. The rye can
be swathed or straight combined. DeRosier cautions that windrows
should be thoroughly dry before combining and may need to lay several days
more than expected to achieve a sufficiently low moisture content.
Hairy Vetch
DeRosier has developed his own variety of hairy vetch that can survive
the winters on his northern Minnesota farm. Starting with a strain
called Madison, available in the Mid-West, he bred the plants that survived
his winters over a period of about four years until he derived a strain
acclimated to his area and able to survive the winter with only an inch
of growth before freeze-up. DeRosier normally seeds the vetch during
the same period he seeds rye, between mid August to mid September.
However, vetch can be planted in the spring for use as forage or during
the summer for a green manure. Deep tillage appears to aid root development.
An inoculant should be used with the seed. Well inoculated vetch
roots should contain many pink nodules within which nitrogen is fixed.
Ideal soil will be moist but well drained with a pH of 6.0 to 7.0.
However, vetch can tolerate drier conditions and a broader range of pH.
Hairy Vetch Nodules
As mentioned, vetch can be used as a forage. It can be grazed
in the fall after sufficient development and again in the spring.
It can also be cut for hay, preferably during early to mid flower.
However, the seed reportedly is toxic to cattle, so vetch with the seed
in it should not be grazed or made into hay. If vetch is grown to
produce seed, it should be intermixed with rye for support. The rye
and vetch seed can later be separated using a spiral mill. When used
as a green manure, vetch can be incorporated with a field cultivator, disk,
or chisel plow. DeRosier says a flail mower can also be used to mow
and chop vetch before planting with a no-till drill or a cultivator.
Mat of Hairy Vetch
Conclusions
DeRosier has found buckwheat, winter rye, and hairy vetch to be versatile
cover crops that can be used in a variety of ways to eliminate weeds, nourish
the soil, recapture nutrients, and control erosion in addition to
producing grain and forage. His development and use of these farming
practices has enabled him to save $50 per acre in chemical costs while
growing crops with excellent yield, quality, and higher market value.
As a result, he has been able to farm a significantly increased number
of acres in a sustainable and profitable way.
Opposing the common wisdom that the years of transition from conventional
to organic farming necessarily mean poor crops, lots of weeds, and financial
loss, DeRosier asserts that using the practices outlined above and adapted
to one's own farming conditions can yield profitable production with minimal
weeds even during the transition period. DeRosier's experiments in
converting CRP land to crops lend strong credibility to his assertions.
Sources
DeRosier, Jaime, (1998a). "CRP in a Crop Rotation Program," pp. 16-17,
Greenbook
'98, Energy and Sustainable Agriculture Program, Minnesota Department
of Agriculture, St. Paul, MN, August 1998.
DeRosier, Jaime, (1998b). My Cover Crop Rotation Program,
Published by the author, RR 1, Box 310, Red Lake Falls, MN 56750.
DeRosier, Jaime, (1999). "CRP in a Crop Rotation Program," pp.
32-34, Greenbook '99, Energy and Sustainable Agriculture Program,
Minnesota Department of Agriculture, St. Paul, MN, August 1999.
Frazeur, Andrea, (1997). "Spreading the Sustainable Story," AURI
AG Innovation News, July 1997.
Photos courtesy of Marvin Duhn: Vetch Blossoms, Bee on Buckwheat
Blossoms, Vetch Nitrogen Nodules.
Photos courtesy of Minnesota Department of Agriculture, Energy and Sustainable
Agriculture
Program: DeRosier in Field of Organic Soybeans, Mat of Hairy
Vetch.
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