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Direct seeding corn into alfalfa sod

It can be done!


November 19, 2007
By Bruce Barker

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Direct seeding into old forage stands, like alfalfa, is becoming a more common
practice across the prairies. Made practical with the use of glyphosate to terminate
the forage stand, many producers are now successfully direct seeding wheat and
barley into these stands. But corn?

"Our demonstration showed that direct seeding corn into alfalfa sod is
a viable method to take alfalfa out of production," says Lawrence Papworth,
a seeding and tillage project engineer at the AgTech Centre at Lethbridge, Alberta.
"It helps to eliminate the multiple passes necessary to take alfalfa out
of production with tillage."

Taking alfalfa out of production can take at least three to five passes with
a cultivator or double discer, and cost a lot in machinery, fuel and labour.
With the price of fuel these days, spraying alfalfa just prior to the last cut,
and then seeding directly into the sod the following spring is looking better
all the time. But for producers who depend on the alfalfa for feed, growing
corn silage under irrigation the following year is often the highest value crop
they can grow for the feedlot operation. That is what spurred Papworth on. The
demonstration project was conducted in conjunction with the irrigation branch
of Alberta Agriculture, Food and Rural Development at the Canada-Alberta Crop
Development Initiative (CACDI) farm at Lethbridge. "If you work the land
once, it'll take three more times to fix it," explains Papworth. "That
was the main idea behind the demonstration."

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Ideally, Papworth says that the best crop to seed into sod is a herbicide tolerant
variety. The benefits of direct seeding a herbicide tolerant crop is the ability
to spray the herbicide anytime throughout the various growth stages to eliminate
weeds and the volunteer forage. By the end of the season, the forage should
be completely eradicated. The land will not have been exposed to wind or water
erosion, and the soil structure will have been better maintained than if it
had undergone tillage.

In the trial, glyphosate was applied in the fall at two litres per acre and
a pre-seed application was made on May 28, two days before seeding, at a rate
of one litre per acre. Two in-crop applications of one litre per acre of glyphosate
were made June 25 and July 3.

Precision planter not necessarily needed
In the AgTech demonstration at the Canada-Alberta Crop Development Initiative
(CACDI) farm at Lethbridge, Papworth compared three drills. Dekalb Roundup Ready
corn was direct seeded into the alfalfa sod on May 30. Half of the field was
seeded with a precision John Deere 1780 MaxEmerge II disc row crop planter set
at 15 inch row spacings. Two passes were seeded with a 17 foot Flexi-Coil 5000
air-drill fitted with Stealth narrow knife single shoot openers on nine inch
spacings, and eight passes were seeded with the eight foot AgTech research plot
air-seeder fitted with Flexi-Coil Barton double shoot disc openers on 12 inch
spacings.

Table 1. Plant stands were good but variable.

Seeding drill Targetted plants
per 24in
Acutal plants
per 24in
John Deere row crop planter 2 2.9
AgTech plot seeder 1.6 4.3
Flexi-Coil knife seeder 1.2 3.5
Source: AgTech Centre.

The Flexi-Coil air-seeder tank used a special segmented roller for more accurate
seeding of corn. The seeding rate was 35,208 seeds per acre (87,000 seeds per
hectare), or 23.5 pounds per acre (26.3kg/ha) with all seeding units.

On May 17, the field was broadcasted with 34-0-0 nitrogen fertilizer at a rate
of 120lb/ac (134kg/ha) of actual N. Phosphate, 11-52-0, was pre-banded on May
18 with a low disturbance disc applicator at 45lb/ac (50kg/ha) actual P.

Well-above normal rainfall throughout May (amounting to 10 inches) eliminated
the need to irrigate until July. A total of 6.25 additional inches of irrigation
water was applied throughout July with the last application on September 16.

Papworth says that plant stand establishment and crop growth was very good.
While all the seeders had higher than desired plant populations, he says that
the stands were fairly similar. "None of the drills had precise metering,
with actual plants per 24 inch row higher than desired. However, all the units
provided good stands."

Papworth says the AgTech and John Deere stands were very similar. There were
no bare patches and the emergence looked very uniform, indicating the metering
systems metered evenly, but at a higher than necessary rate. The Flexi-Coil
seed had many bare patches and thick patches with dense growth, indicating surging
of the metering system. However, the average plant population of the bare and
dense patches was equal to the population stands of the other two seeders.

Unfortunately, a hail storm passed through the corn field on August 10, causing
significant damage. As a result, individual yield results were not taken, but
the average yield across the field was six tonnes per acre (15t/ha), which is
significantly lower than typical corn silage in the area.

While the yield results were wiped out, Papworth says the stand establishment
and general progress of the crop, up until the hail storm, showed that the practice
of seeding directly into sod has potential. Because the demonstration did not
include a field of alfalfa removed with tillage, direct comparisons cannot be
made. The best guess, given the hail storm, must come from plant stands and
crop development. "Based on what we saw in the field, I think the yields
would have been similar," he says.

However, even if corn direct seeded into alfalfa sod gave up some yield, considering
the expense of taking alfalfa out with tillage, the practice still might come
out on top. -30-