Ames, Iowa
March 6, 2009
Source:
Becker Underwood
For the past 14 growing seasons,
Jim Beuerlein, professor of agronomy and soybean research and
extension specialist for The Ohio State University, has
evaluated rhizobial inoculants in hundreds of field trials
across the state. Those trials have shown an average yield
increase of 1.94 bushels per acre for inoculated seed.
"Our evaluations are performed in fields that essentially offer
optimum growing conditions for soybeans and we’ve still seen an
average yield advantage of nearly two bushels per acre,"
Beuerlein says. "These conditions have helped create an
artificially low benchmark. In many instances, I believe growers
will see even better results in their own fields."
In a question and answer session with
Becker Underwood,
Beuerlein shares insight and perspective on his research and the
value of rhizobial inoculants.
Since 1995, you’ve
overseen a program in which you’ve evaluated soybean seed
inoculants. What are the most significant findings resulting
from that program?
Beuerlein: The most
significant finding is that inoculation works, even in
fields and soils where you wouldn’t expect to see much
response. We have tested inoculants in a corn-soybean
rotation, in fields with high-quality soils, where pH is in
the ideal range of 6 to 7, with excellent surface and
subsurface drainage. These are the types of conditions where
you wouldn’t expect to see much response, and yet, over time
inoculants have consistently delivered an average yield
advantage of nearly two bushels per acre. It’s reasonable to
expect most producers would see even greater response in
their fields.
Are there certain situations or conditions in which
inoculants seem to generate a greater response?
Beuerlein: In general,
you would expect to see a greater response from inoculants
in fields with a soil pH below 6 and on ground where
soybeans haven’t been grown in several years. For instance,
one year we had to move a test site at the last minute and
ended up in a field that had been in continuous corn for
eight years. The field was well-drained and had good
fertility, but an organic matter content of about 1.5
percent along with a low soil pH. The yield increase due to
inoculation ranged from eight to 11 bushels per acre,
depending on the product. This really reinforces how
valuable inoculation can be when there are few native
rhizobia bacteria in the soil and when pH and organic matter
levels are low.
Some industry analysts are projecting as many as 80
million acres of soybeans will be planted in 2009. A
significant portion of these acres will be soybeans planted
into fields that have been in continuous corn for several
years. What is your advice to growers who may be planting
soybeans into these types of fields?
Beuerlein: Typically,
fields that have been in continuous corn for several years
will have some rhizobia present, but the populations are
very low and they don’t generate enough nodules to supply
adequate nitrogen for a high-yielding soybean crop. In this
type of situation, it is very likely that a grower will see
a large yield response from inoculation. Another thing to
keep in mind about continuous corn acres is these fields
often have a low soil pH and need lime. If the soil pH is
below 5.7 and not limed, we highly recommend an inoculation
product containing molybdenum.
Another situation many growers in the upper Midwest will
be facing in 2009 is planting soybeans into fields that were
flooded in 2008. Why should growers who are planting into
fields flooded in 2008 consider treating their soybeans with
a rhizobial inoculant?
Beuerlein: Based on our
experience, saturation and flooding for as little as two to
five days will create an anaerobic soil environment that
will kill most rhizobia. Over time, these flood-damaged
fields will gradually become reinoculated through small
amounts of soil moved by wind, water, machinery, insects and
animals. Still, I would not advise growers to rely on Mother
Nature to solve this problem. My recommendation is that they
take matters into their own hands and inoculate their
soybeans with one of the highly effective and inexpensive
rhizobial products that are available to them.
Do you consider the use of inoculants to be sound
management in today’s soybean production? Why?
Beuerlein: I definitely
consider inoculation to be a sound management decision,
especially in today’s market. Almost anybody should get at
least two additional bushels per acre. At today’s prices,
most inoculation treatments can be paid for with an
additional one-third bushel per acre. Our evaluations have
shown that, over time, inoculants deliver a 300 percent to
500 percent return on investment, and they do this over a
wide range of soil types and production systems. To me,
inoculants are one of the most consistently profitable
inputs growers can use in their operations.
How have rhizobial inoculants changed in the past five to
10 years?
Beuerlein: Inoculation
products are many times better today than they were just a
few years ago. For most products, the cell count has been
increased by 100 to 10,000 times per gram. All products have
cell protection agents to extend survivability of the
bacterial cells on the seed and in the soil. They also
contain nutrients that allow the cells to increase in number
after packaging. Inoculation products may contain materials
that speed the development of nodules, or increase the
growth rate of young soybean plants, or reduce the
competition between rhizobia cells and other soil microbes.
Today, most inoculation products contain multiple strains of
rhizobia that allow the products to perform well over a
wider range of soil conditions. In short, the soybean
inoculants we have today are like high-powered race cars,
while those from 10 years ago are more like the first
assembly-line cars of the early 1900s.
Industry estimates show that inoculants are used on only
about a third of U.S. soybean acres. Why isn’t the use of
inoculants more widespread?
Beuerlein: I think there
are a couple of factors at work here. Until just a couple of
years ago, producers had to do their own inoculating, and
many felt it was just a hassle. Today, growers can get their
seed already treated with inoculant, which is much more
convenient. The other reason we haven’t seen as much use of
inoculants is due to the research that has previously been
done at some Midwestern universities. Oftentimes, inoculants
are dismissed because a two-bushel increase over a 50- to
60-bushel yield isn’t considered to be statistically
significant. But that two-bushel increase – generated with a
nominal investment – is very economically significant. The
fact is, inoculation does work, and it has proven itself to
be very profitable in the real world.
What is your advice to growers who might be considering
using inoculants on their soybeans?
Beuerlein: My advice is
to give inoculants a try in a side-by-side comparison,
either in test strips or by simply dividing a field using
inoculant on one half and no application on the other half.
Check the differences in yield and then keep in mind that,
at today’s soybean prices, any advantage of more than a
third of a bushel is going to be profitable.
Becker Underwood, Inc., founded
in 1982, is an international developer of bio-agronomic and
specialty products. In addition to being the leading
manufacturer of seed coatings and colorants, the company is also
the leading global producer of inoculants, beneficial nematodes,
and a wide range of agricultural and horticultural products. To
learn more about its products, visit the company’s Web site at
www.BeckerUnderwood.com.
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