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Features Agronomy Soybeans
Delving deeper than just yield

Determining the 'why' may be more important.


November 13, 2007
By Ralph Pearce


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14aTo some, Dale Cowan set himself a nearly impossible task: to grow 100bu/ac
soybeans on a field at his brother Larry's Chimo Farms operation near Melbourne,
Ontario. Whether he actually met that goal was less of an issue for Dale, president
of Agri-Food Labs in Guelph. He wanted to learn more about why he could reach
the intended goal, or just as important, why not.

Worth mentioning is the fact that the field did not meet the stated goal, but
then 2005 was the first year of the AgTest 100 experience. Instead, Cowan learned
more about production parameters, including controllable and uncontrollable
impacts like weather. Combined, he could see their impact on soybean yields,
and will use that information to prepare for the second year of this field-scale
experiment. "At the end of the season, you can go back to critical points
like flower initiation, and look at why we abort our bottom two sets of pods,"
says Cowan, noting they contribute significantly to overall yield. "And
you note that 15 to 20 days with temperatures over 35 degrees C in the region
helps explain things at that growth stage."

The field set-up
The concept of growing 100bu/ac soybeans has long-been discussed. Dr. Gary Ablett,
now chair of the Plant Agriculture Department at the University of Guelph, broached
the subject years ago, theorizing that if all parameters were monitored and
optimized, 150bu/ac yields were not out of the question.

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In order to provide the best possible footing for such crop yield, Cowan worked
backwards from 100bu/ac, calculating the seeds per acre and row spacing necessary
to give a density of 280,000 plants per acre at harvest. Next in the planning
was equal distance plant spacing, achieved by planting at half rate twice on
a 45 degree angle. The third of the three standards was to ensure nitrogen would
not be a limiting factor. At a yield of 100bu/ac, soybeans would need 600 pounds
of nitrogen per acre. Since it can be assumed that soybeans will fix two-thirds
of their nitrogen via nodulation, Cowan applied a single pass of 190 pounds
of pre-plant nitrogen, banded 10 inches deep.

Other field operations included two applications of glyphosate, one with Folicur
(tebuconazole), two passes to apply foliar micronutrients, another application
of micronutrients with Folicur, and a pass for aphid control. With these applications,
tramlines were established, but with the aphid control, the custom sprayer's
wheel base was different. As a result, roughly three bushels per acre in yield
were lost.

Dissecting the results
At harvest, the results were less than what they had originally set out to show:
instead of 100bu/ac, he wound up with 52. But Cowan is far from disappointed,
again, because of all he learned from the incoming data. Variability in some
parts of the field were explained by looking back on gathered weather data and
taking soil traits into consideration, as well. "What's starting to come
out in some of these other areas is that your cash crop economics are forcing
cutbacks in corn fertility, so we're growing corn with less fertilizer,"
says Cowan. "It stands to reason that at some point, we need to be on the
lookout for soil test levels dropping to responsive ranges that may impact on
soybean yields, as well."

Just having the technology is not enough, he adds. Understanding how it works
and then properly applying the information it provides is the key. "When
you start to see these 20 bushel differentials in yield across the field, and
look at the price of beans, you're looking at $200 per acre in reduced income,"
stresses Cowan. Too often, he adds, growers refer to their yield maps without
necessarily understanding what the maps are actually telling them. "For
14 years, you look back on that same acre that's been yielding half what the
rest of the field's been yielding, and all of a sudden, that's about $3000 to
$4000 an acre in lost revenue."

It is not that a grower has one bad acre, he says. It is the one bad acre that
drains the income or profit from three or four good acres. Growers need to become
more aware of everything that affects crop performance, including organic matter,
organic carbon, calcium carbonate content, depth to solum layer, soil moisture
readings and moisture deficits. And, if for no other reason, than for the sake
of gathering information so it is readily available. "Growers have to become
better acquainted with the concepts of measuring the good acre versus the bad,
and learn to compensate for the latter."

Another point to take home relates to scouting at specific times of the growing
season. At critical stages, like at R5 to R6, growers are supposed to scout
for aphids. "But that's almost a month long, and that is a tremendous effort
on scouting and a strain on all our businesses to go out in those fields three
times a week for a month to check aphid thresholds," says Cowan. "So
we need to revisit that one."

Pulling it all together
Ultimately, what Cowan wants to do with this information is show more of what
is possible in terms of using the technology. In 2006, he wants to further the
research and show how variability can be overcome, how the low ends on the yield
scale can be raised, and how growers can improve their bottom line by thinking
things through. "You have to be prepared to sit down and look at where
the inputs are going, where the return is coming from, and take the approach
that looks at this 100 acre farm, but makes you realize you can only make a
living off 75," states Cowan. At some point, he notes, there is no place
else to turn to create more margin or income. "You have to start looking
at the assets that you own and say, 'I'm running at 75 percent efficiency, so
what are those other things I need to do?"

One thing he advocates is a cut back in planting on headlands. If a grower
wants to save five to 12 percent of his operating costs, avoid planting the
headlands. "It's a lose-lose situation in almost every field I've seen,"
says Cowan. "Just don't fertilize, don't plant it, and find the cheapest
Kentucky blue grass you can and plant that instead." -30-