Features Agronomy Other Crops
Cornbelt moves north

When Hollywood decided to turn author W. P. (Bill) Kinsela's short story Shoeless
Joe into the blockbuster film 'Field of Dreams' in 1989, they chose to film
it in the heart of the cornbelt, Dyersville, Iowa. Today if they were filming
the story about a magical baseball diamond carved out of a corn field, they
could choose to film it right outside of Kinsela's home town, Edmonton, Alberta.
Thanks to a new generation of short season corn hybrids, corn is becoming an
increasingly popular choice for silage as far north as Alberta's Peace River
district.

According to Ray Gautier, a field sales agronomist with Pioneer Hybrid in Alberta,
the rising acreage of corn in central Alberta can be attributed to the development
of earlier maturing corn genetics that has made corn a viable choice in northern
regions. At the same time the demand for these early varieties is partially
being driven by an influx of European immigrants buying dairy farms in the region.
"They're used to growing and feeding their dairy cows corn," Gautier
says. "They know the benefits of corn silage and want to use it here. More
recently, we've also seen cow/calf producers showing an interest in grazing
corn during early winter as an option for swath grazing with barley or feeding
hay in a field."

When Gezinas (Gus) Martens emigrated from Holland in 1998 to start a dairy
farm at Calmar, Alberta (near Leduc), there was no corn being grown in his area.
Today the corn silage he grows on his farm is a large part of his dairy ration.
"Corn silage is a complete, healthy food for the cows," he says. It
also significantly out yields barley. "We have averaged between 16 and
18 tons an acre with corn silage for the last four years; with barley silage,
10 tons an acre is a good crop."

It is well known that producers in central and northern Alberta benefit from
very long days. Hours of sunlight alone are not enough to generate all the corn
heat units (CHU) that long season corn varieties require. CHUs vary dramatically
across the province depending on latitude, altitude and topography. While 80
day corn varieties perform well in the Taber/Vauxhall region in southern Alberta,
even a 70 day variety can struggle in central and northern regions.

Using an early maturing variety really paid off for growers in 2005. In parts
of central Alberta, CHUs were down by as much as 300 units. "Corn had a
great start in 2005," Gautier says. "We had a warm spring, good moisture
and the cob potential going into August was unbelievable. It cooled down in
August and the corn took forever to start to mature. We lacked the heat to finish
this year."

"That's why 70 day varieties, like Pioneer Hybrid's 39F45, work so well
year in and year out," Al Grombacher, a corn breeder with Pioneer Hybrid
in Edmonton, says. "Corn is a pretty forgiving crop but even in a normal
year, with normal heat units, you still require a certain amount of time for
it to mature."

"When you are selecting a corn variety, you have to pay attention to maturity,"
Gautier says. "A 2400CHU corn will not do well in central Alberta. If you
try to grow a corn variety that's far outside of its area of adaptation, you're
not going to see proper cob development. This can not only cost you half of
your silage tonnage but also the starch and energy benefits from the grain."

In central and northern Alberta F45, rated at 2000CHU, sets a standard for
early maturity. Since it is a conventional variety, weed control can be an issue
if it is not planted on clean fields. Roundup Ready corn varieties give great
weed control but the earliest fall into the 2200CHU range. "A 2200 corn
will give you ideal silage in a normal year but less than ideal silage in cooler
years," Gautier says. "But if you have big weed control problems though,
you might have to compromise." Many producers, like Martens, prefer not
to compromise. They want corn breeders to give them more choice.

"I think there is a bigger weed problem here than anywhere else,"
Martens says. "If we are seeding at the end of April, it's too cold for
the weeds to be growing so there is often no point using a glyphosate burnoff.
Cool springs slow plant growth so the canopy stays open until the last half
of July; sometimes farmers have to spray twice."

For a corn breeder like Grombacher, the guiding principal when developing varieties
suitable for northern regions is 'the earlier the better'. "At Pioneer,
we're aiming for varieties that are earlier than 39F45," he says. "We're
currently working on lines that require similar or even fewer heat units and
still maintain silage corn quality. Both the company and I believe we can diversify
the silage market and create a win-win situation for the farmer."

Having early maturity is not enough; new varieties have to have the right agronomics
too. Many northern Albertan corn growers have dairies or other intensive livestock
operations, so new varieties have to be able to thrive under high fertility.

"If you plant barley in a heavily manured field, big patches will fall
over. The straw is too weak to hold up all the grain in the heads," Grombacher
says. "You want to avoid that in corn too. Most corn varieties can tolerate
extremely high fertility without falling over because we breed for high yield.
You also have to look at the height of the plants, where the ear is on the plant,
all these things help with standability."

First time growers
Planning on trying corn for silage for the first time? Ray Gautier, a field
sales agronomist with Pioneer Hybrid in Alberta, suggests picking as early a
maturing variety as possible and to seed early.

"Corn needs a certain number of heat units to come out of the ground,"
Gautier says. "Once it does, it will take a spring frost because the growing
point remains below the ground surface. You might lose a few leaves and you
will see a bit of a delay, but I don't think the impact would be as bad as seeding
late."

Typically corn is silaged when it is down to 60 percent moisture content. In
central and northern Alberta it is not unusual to get a frost before the corn
becomes this mature. If you get just a light frost, Gautier suggests not rushing
out and cutting it but waiting and letting it mature. If it was a killing frost
(below minus three degrees C) and the cobs turn brown, most producers would
go ahead and start cutting.

"Don't wait until the whole plant dies off and looks like tobacco,"
dairy farmer Gezinus Martens of Calmar, Alberta says. "It will have a higher
feed value if you wait but there isn't much taste to it. One year our corn froze
off so badly that the cows didn't like it. We had to put some molasses in our
ration to sweeten it before the cows started eating. I like to take it off a
little earlier, when you still have some green cobs. The energy is maybe a little
bit lower but the cows like it more. Taste is really important to cows."
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Calculating crop heat units

When selecting a corn hybrid, start by looking at those with crop heat unit
(CHU) requirements that fit your area. All hybrids have a CHU rating that indicates
the number of warm days a hybrid needs to mature. Since planting the wrong hybrid
can drastically affect silage quantity and quality, it is important that producers
know how many CHUs their farm can expect to receive.

Not sure how many CHUs your farm will record over the growing season? A good
place to look is your provincial department of agriculture's website. Alberta
Agriculture, for example, has a map showing the average number of growing season
CHUs accumulated across the province at: www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/sag6442?opendocument

The average CHUs from 1971 to 2000 ranged from a high of 2544 at the Medicine
Hat airport to less than 1600 in the foothills of the Rockies. Almost all of
Alberta south and east of Edmonton usually receive between 2000 and 2200 CHUs.

If you wish to determine how many CHUs your farm collects over the growing
season, start by determining what your daily heat units are. The simplest way
to do this is by recording your daily minimum and maximum temperatures and as
long as the overnight low is greater than 4.4 degrees C, enter the recorded
temperatures into one of the many online Crop Heat Unit calculators like the
one featured on the Ontario Weather Page at: www.ontarioweather.com/industry/agriculture/agrcornheat.asp

This will quickly and easily give you your daily heat units.

Once you have these, you can determine your yearly growing season CHUs simply
by adding all the daily CHU numbers together. Counting starts from the last
of three consecutive days with daily mean air temperatures of 12.8 degrees C
or greater. Usually this is very close to the time corn is planted, about the
time when soil temperatures reach the 10 degrees C when corn germinates. Counting
continues until either the corn reaches 32 percent kernel moisture or the temperatures
dip to minus two degrees C.

If you do not have access to the internet, calculating heat units becomes more
labour intensive. Once again, start by recording daytime high and low temperatures.
Once you have your minimum/maximum temperatures you can determine your daily
crop heat units by using a table which you should be able to get from your seed
corn provider. -30-