improved malt quality,” said O’Donovan. “There was a slight
reduction in kernel plumpness, but we felt the uniformity of the
seed was more important.”
The research also showed that at the 300-seed rate, protein
was slightly lower, which is more desirable in malt barley. And
by going from 200 to 300 seeds per square metre, crops
matured two to three days sooner, “which can make a huge
difference when quality is the key and frost can quickly damage
a crop,” he said.
O’Donovan said it should be noted that his team’s research
plots were direct seeded with an air seeding system calibrated
for 300 seeds per square metre. With that system, they targeted
70 per cent emergence, or about 220 to 230 viable plants per
square metre (about 22 to 23 plants per square foot).
“So if you have a seeding system where you are expecting
95 per cent emergence, for example, then you would need to
adjust your seeding rate so you end up with about 220 to 230
plants per square metre,” he said.
Going beyond 300 seeds per square metre didn’t help with
malt barley, said O’Donovan. At 400 and 500 seeds per square
metre, yield was significantly reduced, likely due to lodging,
and the economics of higher costs associated with the higher
rate didn’t pencil out.
In southern Alberta, Ross McKenzie, a longtime AARD
research scientist now retired, said his research with crops
produced under irrigation showed the optimum seeding rate
for malt barley was 17 to 24 plants per
square foot (he targeted 180 to 250 seeds
per square metre).
For feed barley under irrigation, it was
slightly higher at 19 to 33 plants per square
foot (200 to 350 seeds per square metre).
And for Hard Red Spring Wheat under
irrigation, 19 to 28 plants per square foot
(200 to 300 seeds per square metre).
McKenzie said that while every seeding
system is different, he figures on an
average emergence of between 60 and 80 per cent.
“With most seeding systems, if you are targeting a one-inch
seeding depth, for example, you’re going to get some seeds
at half an inch depth and some at two inches,” said McKenzie.
“So you have to adjust the actual number of seeds planted to
achieve the targeted viable plant count.”
Looking at wheat production in dryland farming, McKenzie
said some of his last research published in 2013 showed the
optimum seeding rate for soft white wheat in all soil zones was
300 to 400 seeds per square metre (roughly 30 to 40 seeds
per square foot), which should translate into about 21 to 28
plants per square foot.
With Canada Prairie Spring Wheat on dryland, seeding rates
ranged from 275 to 350 seeds per square metre (28 to 35
seeds per square foot), or a plant count of 20 to 25 plants per
square foot in the dark brown soil zone, and up to about 350 to
450 seeds per square metre or 25 to 32 plants per square foot
in the black soil zone.
McKenzie’s research papers, entitled
Optimum Seeding Date
and Rates for Irrigated Grain and Oilseed Crops
and
Dryland
Agronomic Management of Soft White Spring Wheat and
Canada Prairie Spring Wheat in Alberta,
can both be found
on the AARD website:
infopage?cat1=Crops&cat2=Cereals.
SEED AS EARLY AS POSSIBLE
Along with the seeding rate, McKenzie said another important
factor for farmers to consider is the seeding date. Generally,
researchers and crop specialists suggest an early seeding date
is better than a late seeding date.
“Obviously, you can’t seed every crop on the same day,” said
McKenzie. “But, research shows yield is reduced by about one
per cent per day for each day the crop is seeded after May 1.”
His research showed flax was the least affected by delayed
seeding, losing about 0.6 per cent yield per day after May 1,
while canola was the most affected, losing about 1.7 per cent of
yield for each day seeding was delayed after May 1. Most of the
cereal crops were in the range of one to 1.3 per cent per day.
“The earlier you can get your crop seeded without risk of
damage, the better,” said McKenzie. “You may not want to seed
canola on April 15 due to the risk of frost, but you may want to
consider getting your peas, wheat and barley seeded in late
April if conditions are suitable.”
McKenzie said farmers should look
to get their highest-value crops seeded
first (to protect yield potential) and then
schedule the rest of the crops later.
“If you can’t seed until May 1, and canola
is your highest-value crop, then it would be
best to seed canola first,” said McKenzie.
“Then follow that with wheat and then
barley. Since flax, for example, has the
least potential for yield loss due to later
seeding, you could seed it last.”
According to Brook, temperature is an important factor when
it comes to seeding early.
“You don’t want to be seeding into damp soil that is only
1
°
C,” he said. “You can lose a lot of seed to rot under those
conditions.
“As a minimum, soil needs to be 5
°
C or better at time of
seeding. If you can seed into a warm, moist seedbed, and seed
shallow, that crop has an excellent chance of getting off to a
good start. You might be able to seed peas at 4
°
C, but overall it
is best to wait for at least 5
°
C before seeding.”
O’Donovan had similar recommendations following his
research with malt barley.
“In most areas we found that seeding early—seeding before
the middle of May—produced the better yields,” he said.
“The exception to that might be the Peace River region, where
Spring
2015
Grains
West
34
“Research shows yield is
reduced by about one per
cent per day for each day
the crop is seeded after
May 1.”
–Ross McKenzie
