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 of rye
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 ground water.
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
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 with rye:
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.
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 just yet.
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,” he notes.
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
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 of
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
“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.
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 work.
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 rye.
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
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 the weeds.
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 use.)
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.”