More than 450,000 acres of Manitoba farmland is used to grow
special crops such as potatoes, sugar beets and pulse crops. This land is generally
light-textured and very prone to wind erosion. Complicating the issue is the fact that
special crops produce very little crop residue to protect the soil.
Wind erosion does
more than remove valuable topsoil. It also removes the organic matter that holds the soil
together and retains soil moisture, while improving its tilth and structure. Soils that
have lost much of their organic material become even more susceptible to wind erosion.
Organic matter also provides a kind of nutrient bank, releasing nutrients for crop use.
The best way to protect erosion-prone soils is to use a complete management system
including shelterbelts, annual barriers, proper residue management and crop rotations.
Cover crops are an important component of the system. Consider a Cover Crop
The sole purpose of a cover crop is to protect the bare, erosion-prone land from the
wind. They are usually seeded after the harvest of a low-residue crop such as potatoes or
in the spring to protect the soil until the new crop has grown enough to protect the land.
Fall rye is the most commonly-used cover crop, although other cereals such as wheat,
barley, and oats are also used.
A fall cover crop must grow enough before freeze-up to provide protection to the soil.
The latest recommended seeding date for fall cover crops will vary depending on the
weather, but used September 15th as a general guideline.
Fall rye is often left for harvest the next summer - as part of the crop rotation. If
you are planning to allow fall rye to survive as a crop the following spring, adjust your
seeding deadline accordingly. It's A Fact
Cover crops have the added benefit of capturing snow over the winter to enhance
moisture conditions in the spring. One foot of snow collected equals approximately one
inch of water. Establishing Fall Cover Crops
Fall cover crops are best suited for potato land or pulse crops. Sugar beets are
harvested too late in the year for a cover crop to become established. Option One: Seed with a fertilizer broadcaster prior to harvest
This method can work well on potato fields because of the significant amount of soil
disturbance associated with the harvest. The cover crop seed is incorporated by the potato
harvester and the operation used to anchor the potato vines after harvest.
Seeding Rate - 2 bushels/acre because some seed will remain on the
surface and some will be buried too deep to germinate.
Advantages
- uses moisture brought to the surface by the potato harvest
- relatively fast operation
- early seeding allows the cover crop more time to establish before freeze-up
- don't have to take valuable time during harvest to seed
Disadvantages
- Requires a higher rate of seed application than post-harvest seeding
Option Two: Seed after harvest
On potato fields, seed the cover crop within 12 hours of the harvest to take advantage
of the moisture brought up by the harvesting operation. Some operators seed their cover
crops at the end of each day of harvesting. A press drill is preferred because of better
packing and fewer problems dealing with potato vines. Hoe drills and air seeders have a
tendency to plug up with vines.
On pulse crop fields, cover crops may be seeded with any one of a variety of seeders
but packing is important to obtain a good seed-to-soil contact in soil that is likely to
be dry. In-line packers are the most efficient.
Seeding Rate - 3/4 to 1 bushel/acre
Advantages
- drilling the seed into the soil rather than broadcasting it results in better
germination and allow lower seeding rates
- on potato land, it uses moisture brought up by harvesting
Disadvantages
- dealing with potato vines
- takes more time and horsepower than broadcasting seed
Option Three: Seed cover crops from an aircraft prior to harvest
Seeding cover crops with an aircraft can be effective and economical, especially where
large areas of land are involved. Costs per acre for seeding from the air are comparable
to other methods when considering the operator's time, operating costs, and wear and tear
on machinery.
Advantages
- Time. The producer doesn't use valuable time seeding and a lot of acreage can be seeded
in a short time.
Disadvantages
- Uneven distribution of seed among hills and furrows may be a problem.
For more information about seeding from the air, contact your
local MAFRI office.
Anchoring Potato Vines
If potato vines are not anchored, they will roll up and blow away. Use a disc with
two-thirds of the discs removed to anchor vines. Have it set up for burying the vines, not
for tillage. Travel slowly - about 3 miles/hr - in same direction as the rows or diagonal
to them. The operation will leave some cover and ridge the soil.
Using a vine chopper attachment on the potato harvester eliminates the need to anchor
the vines. Removing a Fall-planted Cover Crop
Normally, a cover crop will be killed by frost before it grows too much to be a
problem. However, if the cover crop's use of soil moisture and the potential amount
of straw on the field the following spring are becoming concerns, use a herbicide to kill
it.
Fall rye may be left until spring, then burned off with a herbicide either before
seeding a new crop or pre-emergence. Planting the New Crop
Direct seed the new crop into the cover crop residue. In the case of fall rye, burn off
the new growth before seeding or immediately after seeding. Spring Cover Crops
Since potatoes and pulse crops are most often seeded into cereal stubble as a part of
crop rotation, wind erosion is generally not a major concern in the year of establishment.
However, sugar beet production poses special problems.
Sugar beets are generally seeded into bare, pulverized soil. It takes up to six weeks
before the new crop is thick enough to provide protection for the soil supporting it. Wind
blown soil can act like a sand blaster to bombard young plants and cause damage, cutting
or shearing them off in extreme cases.
A cover crop of wheat or other cereals should be seeded as early as possible in the
spring, prior to planting beets. Cereals will emerge quickly and provide protection to the
soil. The beets can be planted directly into the growing crop later. The cover crop will
also protect the young beets from the wind. Remove the cover crop with the appropriate
herbicide once the beets are at the four-leaf stage. For More Information, contact:
Agri-Environment Knowledge
Centre Manitoba Agriculture, Food and Rural Initiatives PO Box 1149 Carman, MB R0G 0J0
Phone: (204) 745-5664
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Prairie Farm Rehabilitation Administration
Morden Research Station 200 - 101 Route 100 Morden, MB R6M 1Y5 Phone: (204) 822-4078 |
Or Contact :
Your local MAFRI office.
Funds for the preparation and printing of this fact sheet
have been provided by: Buffalo Plains Soil and Water Management Association.
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