Top Crop Manager

Features Agronomy Cereals
Tying some loose ends on wheat

Early planting, low populations and more.

November 12, 2007  By Top Crop Manager

6aEach new growing season brings another idea, another facet, another twist in
the way growers manage their crops. Yet each year, researchers and agronomists
find more questions from the previous yearÕs answers.

Such is the way for Peter Johnson, cereal crop specialist with the Ontario
Ministry of Agriculture, Food and Rural Affairs. Despite another massive wheat
crop in Ontario, the learning process never stops. From planting dates to seed
populations to managing residues, Johnson has a growing list of test plots and
points to ponder. "In Germany, if you plant early, you're actually down
to 0.8 million seeds per acre," says Johnson, noting conventional standards
for Ontario are 1.5 million and 1.8 million on clay soils. "I've expanded
those seeding trials, so I'm at 0.9, 1.2, 1.5, 1.8 and 2.1 million seeds."

On planting dates, Johnson has found considerable fodder for more research.
Late planting is a popular subject with his work on November and December plot
tests. He also is finding some discrepancy on what is considered timely planting.
"In 2005, I would have said that we planted 80 or 90 percent of the crop
on time and after the fact, it appears we only seeded a third of the crop on
time," says Johnson. "Whatever happened because of the mild winter
or the fall conditions we had, that wheat, planted on October 5, which was supposedly
on time, was actually late."


Dates and populations together
When he mixed planting dates and populations, another interesting twist emerged.
Wheat planted prior to the end of September showed little injury or difference
between 0.9 million and 2.1 million seeds per acre. But planting into the first
or second week of October, he saw considerable damage to low populations in
plots that were prone to frost heave. "It comes down to the fact that if
I have 2.1 million plants, the roots interlock enough that if it gets frost
heave, they're helping each other," explains Johnson. "I have strips
in fields where the frost-heave prone knolls with 0.9 million seeds is 85 percent
gone and right beside it, the 2.1 million strip shows no problem."

Seeding in winter
Another of Johnson's test strips yielded some unintended findings. Seeding around
December 18, he saw poor initial results; but in that particular trial, he had
a strip with a four foot overlap where the wheat survived. "It wasn't just
a double population; the first pass broke the frost and the second pass was
planted deeper," says Johnson. "So the seed was in 1-1/4 inches to
1-1/2 inches, and provided insulation above the seed, and newly germinated seed
isn't as cold tolerant as wheat that hardens off."

Wheat plants have to reach the two or three leaf stage to harden off properly,
and where it was insulated, even though temperatures dipped to minus 15 degrees
C, the plant never got below minus nine degrees C. Johnson found a similar scenario
on a plot where the frost barely held-up the tractor, yet allowed an even depth
of about one inch. The result was a perfect stand of both winter and spring

The conditions vary too much to allow for any one set planting date, fall,
winter or spring. "We have to be careful about going too early," says
Johnson, acknowledging that he would like to do some plots August 30th, September
15th and September 30th to test that early date. He knows of some growers along
the Lake Erie shoreline who plant on September 8 and yield 95bu/ac. "But
if they had planted September 25th, it might have gone 110, and maybe it wouldn't,
but we really need to figure that out."

Managing residues
With larger combines and wider headers, managing residues has taken on greater
urgency, because they can cause problems whether wheat is being planted into
soybean ground, soybeans into wheat ground or no-till corn into wheat ground.
The problem is that a 30 or 35 foot header will concentrate wheat chaff or bean
hulls into a five foot wide swath behind the combine. Soybeans have so little
straw material, there is not enough mass to throw with a straw chopper and the
hulls drop before the chopper anyway. With edible beans that have been pulled,
often putting two sets of eight rows into one swath for the combine.

"When you plant wheat into those fields, the soil is loose and most guys
won't spread that trash, and you can see every strip in the following wheat
crop," explains Johnson, noting that most edible bean combines do a poor
job of spreading residue.

The answer is to purchase an after-market straw chopper and chaff spreader,
but most growers try to avoid the added cost. "If you think of all the
nutrients in that residue, spreading back on 20 feet, not 30 feet, I'm getting
these strips in the field that need to be managed differently, but we've been
just ignoring it and living with the results," says Johnson.

Also, Johnson is uncertain that with a 35 foot header, it is possible to throw
residue the necessary 18 feet, especially on a windy day. But poor residue management
is obvious and Johnson has seen fields where residue has caused significant
plant loss. "The reason we know it is the combine swath is because it is
on a diagonal and nothing else was done on the diagonal. It was a 20 foot header
and every 18 feet, we have these strips about the width of the combine body
and they're dead," relates Johnson. 


Stories continue below