SEPTEMBER 12, 2003: If there existed, somewhere
in the known universe, a highly effective organic weed control,
organic producers everywhere would be singing its praises
and lining up for their share. Though a silver bullet does
not exist, hope remains for improved weed control. Researchers
and inventive farmers continue their search for rotations
and intermingling planting methods that take on weedy fields
and return meaty yields.
One of the Cinderellas of this story could be rye, currently
under investigation in Minnesota as a companion for soybeans
to curb weed growth. Paul Porter, agronomist at the University
of Minnesota, is working with five farmers to determine the
methodology for, and efficacy of, planting soybeans in fields
that were sown with rye the previous fall.
This study is benefiting from the experience and knowledge
of Robin Brekken, a farmer from Crookston, Minnesota, who
began transitioning to organic in 1998. Although this is only
the first year of the study, it is Brekken’s fourth
year of planting soybeans into rye. History has shown him
that rye holds promise. Each year has presented slightly different
challenges for Brekken, and this year has been no different.
Yet Brekken’s time spent with rye may help provide a
fine-tuned recommendation for future use of rye as a weed
suppressant. With 3,000 acres to tend to, he’s on a
quest for something efficient and effective.
Flaming can be a very effective weed control, Brekken says,
provided a farmer can get into the field. But this spring,
wet weather plagued parts of Minnesota and kept equipment
and farmers out of fields.
In this setting, Brekken finds the rye alternative attractive.
It can provide a potent mixture of allelopathy and shade for
the soil, inhibiting weed seed germination. Soybean seeds
are large enough to germinate and flourish amidst a stand
of rye. The key is getting the rye established in fall, prior
to next spring’s soybean crop. Brekken has learned that
this requires a bit of finesse.
Learning to capitalize on the many benefits
To help farmers develop the right plans—timing, varieties
and methods—for using rye, Porter wrote a grant, which
was awarded by the Minnesota Department of Agriculture. The
grant is part of a project supporting efforts aimed at increasing
knowledge about sustainable agriculture and energy sources.
The idea for the grant came to Porter from farmer folklore
in Minnesota: The saying goes that soybeans are made in August.
Porter theorized that with the use of rye, a farm could more
easily capitalize on the most productive time of year for
soybeans. The rye could help diminish weeds and retain moisture
earlier in the season, nurturing a good stand of beans. Then,
with good weather, the crop would be a good one.
The grant is looking at using rye in both conventional and
organic production systems. Farmers routinely use herbicides
to control weeds in soybeans, and Porter notes that some of
these have a negative effect on the soybeans. His hope is
that rye would make this process easier on the soybeans by
providing more effective weed control.
Finding candidates willing to participate in the study was
not too difficult. “Some farmers were already using
rye,” says Porter. They were in the midst of determining
the optimal seeding rate and planting date.
Porter also hoped he could take the weed control notion one
step further, turning it into a best management practice for
other reasons. Rye appears to improve environmental conditions
all around the field, says Porter. The fall-planted rye crop
is a valuable asset in controlling runoff and nutrient leaching.
The rye plants capture and hold nutrients and moisture in
place, reducing the amount that reaches rivers, streams and
In much of Minnesota, there is often excess water in the
soil at certain times of the year. For example, notes Porter,
“in the fall, these areas often get a soil moisture
recharge in the form of rain.” Then in spring, heavy
rains cause runoff through the soil into both surface and
subsurface drainage tiles.
Initially, Porter conducted research in southwest Minnesota
to determine what would happen if rye were seeded after corn.
He and his colleagues documented that runoff was substantially
reduced. Rye doesn’t halt all erosion, but it can reduce
it, along with the amount of nitrogen in runoff water.
It was then that farmers like Brekken caught Porter’s
attention. Brekken, along with other organic and conventional
growers in the state, was planting rye in the fall, ahead
of soybeans that would be planted later in the spring. Porter
hoped to devise a system for both organic and conventional
farmers to use as a cover crop.
Robin Brekken’s 4-year relationship
he’s still learning
As with many aspects of farming, planting soybeans into rye
is still a process under development. Brekken is no stranger
to the practice, but he has not perfected it yet. Before entering
the study, Brekken had his first experience with rye for weed
control in the fall of 1999. He had begun his transition to
organic production at this point, though he wasn’t fully
certified as organic until the spring of 2001. His plan then
was to solid seed the soybeans with a Case IH SDX planter—using
a drilling method. At this point, he was planting soybeans
at a ratio of 120 lb per acre—double seeding. Almost
immediately, he discovered some of the challenges of the method.
ONE: That year, he tilled the rye when
it reached about 8” to 10” tall. This was done
prior to drilling soybeans in the spring. This approach did
not provide an ideal seedbed, he notes. “The root mass
of rye is incredible—softball sized,” he added.
To deal with this, the fields were tilled again before the
beans were planted. Then, says Brekken, he prayed for rain.
Rain was abundant; so were weeds. Brekken had 100 migrant
workers ready to help him pull weeds if needed. He also planned
to run several different harrows through the fields. The skies
never cleared for long enough to provide the workers adequate
time in the fields. Eventually, Brekken sent everyone home.
Yields were acceptable that year, but Brekken had his doubts
about tilling the next spring. He would not give up on rye
TWO: Hoping to further refine this
method, Brekken decided to try something different in the
spring of 2001. He decided to till again, but left a 40’-wide
strip of untilled rye. After the rye headed—which was
roughly two weeks after the soybeans were planted--this strip
was shredded with an Alloway shredder. He planted the soybeans
amidst the rye. Immediately, he noticed that the soil was
different in the two areas. Moisture was abundant in the soil
under the rye. Brekken says he could have planted the soybeans
½“ deep. “In the tilled area, we would
have planted 4 inches deep just to reach some moisture,”
As the plants matured side by side, it was easy to see something
unique about those in the shredded rye, Brekken recalls. He
noticed early on that these plants were shorter, and a lighter
green in color. In the tilled area, the plants were taller,
with bigger leaves that were a darker green.
Porter is unsure at this point why the color would vary in
the two fields. “Soybeans produce their own nitrogen,
so that’s not a concern,” he notes. Whatever the
rye is taking away from the soybeans is yet to be studied.
Porter notes that the first issue is weed control. Later studies
will determine nutrient management.
Regardless, the color variation and plant size caught Brekken’s
attention. So he took a closer look. He counted the number
of nodes that would eventually become bean-bearing pods on
plants in both the mowed area and the tilled area. Plants
in the two different settings were bearing identical numbers
Later, he found that count to be only the first chapter in
a story full of twists and turns. Despite the less-vibrant
color of the soybeans in the mowed rye, those plants produced
two- and three-bean pods. In the tilled area, plants were
yielding one- and two-bean pods.
“That was when the light went on,” says Brekken.
Eventually, the harvest bore out what this pod count foretold.
“They were nicest beans I had,” he says.
The forty-foot strip yielded about 35/bu acre. Where he had
tilled out the rye, the yield was 28.5/bu. Before transitioning
to organic production, Brekken would routinely harvest 35-38/bu.
per acre. At harvest time, he ran his combine through the
shredded rye strip, and weighed the beans. Then he repeated
the process in the tilled rye. He discovered that the soybeans
in the mowed rye provided an eventual 6.66 bushes more per
acre than the soy where he had tilled the rye.
THREE: The result was surprising to
Brekken, and promising. During the next year, with rye planted
in September of 2001, and soybeans in spring 2002, he decided
to jump to 1500 acres of soybeans, all interplanted into rye
that was shredded two weeks after planting the soybeans. “I
thought it was ironic,” he says. “For less yield,
we made two tillage passes with the cultivator, and we had
planned to make even more passes with the harrow and had migrant
workers in the field.”
In addition, tilling dried out the field. Where rye is mowed,
rain is far less critical because the rye helps retain the
moisture in the soil. However, moisture is still critical,
because the rye itself uses a great deal of moisture. Brekken
notes that if the area ever had a dry spring, the rye may
steal too much moisture from soybeans, preventing germination.
So far, things looked good for the rye: It boosts yield, fields
are cleaner and the process is less expensive.
In the fall, the harvest ranged from just 9 bu./acre to 35
bu./acre. In the areas where the soybeans yield was lower,
the seeds and plants had been washed out by heavy early season
rains. Yet weed control was adequate, and Brekken felt he
had found an approach that, given more ideal weather, could
Having spent many years as a conventional farm, Brekken can
easily contrast rye with herbicides for weed control. “There’s
no guarantee that they’ll work,” he says of the
herbicides. Rye is cheaper than chemicals, to boot. An acre
of rye seed runs about $8; herbicides can run from $15 to
$25/acre. He also senses that planting rye will reduce the
amount of labor involved in raising soybeans organically versus
conventional methods of production. What’s more, he
can also sell the rye produced in the field by having the
product seined, separating the soybeans from the re-emerged
FOUR: As is always the case in farming,
Brekken faced another, new challenge with his rye this year.
Last fall was wet, and the rye was planted later than would
be an ideal time. (Ideally, in Minnesota, rye is planted the
last week in August or the first week in September.) As a
result, more weeds popped up this year in the rye because
it was behind schedule when compared with past years.
Porter had already noted that rye planted later in the fall
provides reduced coverage, and reduced weed suppression. “In
the case of last fall, Mother Nature set the planting date,”
notes Brekken, so there was nothing he could do about it.
Yet he recognizes that this practice is a work in progress,
and his optimism shows: Initially, Brekken thought that this
situation may provide him with a learning experience, and
perhaps also with an even simpler way of killing off the rye
and keeping the weeds in check.
Brekken discussed the weed situation with Porter to determine
some method of dealing with it before planting the soybeans.
The two decided that Brekken should run a harrow through the
fields. He did this two times, and in some cases three times,
through many of the fields. Some fields were left because
the rye was well established and had successfully suppressed
To knock down the weeds, Brekken used a Brandt harrow, which
produces about four to five inches of tillage. The tooth is
large—9/16 inches by 28 inches. This harrow allows the
farmer to tip it hydraulically, and requires a 300 horsepower
tractor just to pull it. “It can be very aggressive,”
Back in 2001, Brekken had noticed that the areas where he
accidentally made two passes when drilling the beans were
exceptionally productive. So this year, Brekken intentionally
double seeded his entire soy crop in this manner. He “solid
seeded” the soybeans by crossing the fields a second
time at a 90 degree angle to the first pass with the soybean
driller. Each acre was planted with 180 lb.—90 lb. in
one direction, and another 90 lb. planted at a right angle
to the first 90 lb. “This is the first year we cross-seeded,
using a no till drill. The disks on the drill cut up the rye,”
says Brekken. This managed to set back and kill enough rye
that he did not need to actually use a shredder this year.
This year thus far has been a mixture of weather that has
been at extremes. The spring was quite wet, and early summer
proved no different. “Earlier in the year, we experienced
a rainfall of four inches in one hour,” says Brekken.
Then, the dry weather set up, with the last measurable rain
falling in the last week in July. Brekken can see that the
plants are sloughing pods at the tops of the plants, and lower
down are sloughing beans within the pods. “If I had
to guess, I’d say I’m going to get two-thirds
of what I could have harvested. This year would have been
the nicest beans I’d ever had,” he notes.
Knowing the role the weather plays, as all farmers do, Brekken
sees the rye/soy method as one that he could perhaps bank
on. Today, on September 5, he’s planting rye. He’s
not giving up on it yet. He knows that he’s in the process
of learning. With the curve balls that the weather throws
at him, like every farmer, he’s willing to take a swing.
He never knows when he may hit a double—or a home run.
Looking to the future: Benefits for both
organic and conventional growers
Porter, too, is optimistic about the project, even though
it is only in the earliest stages. “What I like is that
we’re trying to make the process work in the conventional
world,” he says. Even in conventional production, rye
sucks up and hangs on to moisture, keeping it available for
soybeans. It can provide a no-till method that farmers using
the approach may appreciate. In drier areas, tilling exposes
the soil, allowing precious moisture to evaporate. (For future
study, Porter has recommended that his on-farm collaborators
use two varieties of rye, planted in different fields. These
will be evaluated to select the better of the two for future
Wildlife cover is another benefit. “On one farm, we
kicked up a hen mallard nesting in the rye,” notes Porter.
The rye also provides habitat and feed for deer and geese
in the fall and in spring.
Brekken says he’s not married to rye, but he knows
it has benefits that he’s not sure he can find elsewhere.
“If we can plant and be done, that’s unheard of,”
he says. “But that’s a possibility—we’ve
done that with rye.” In addition, this system gives
him the ability to not worry about weather. After years of
conventional farming, Brekken is married to organic
production of food-grade soybeans. “It’s the greatest
thing: I’m growing something that people want to buy—versus
going to elevator asking what they’re going to give
me for it.”