September/
October 1998
Survive the winter, and winter wheat has advantages
By Dr. Michael Peel, NDSU Extension Small Grains Specialist
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Prairie Grains is the
official publication of
the Minnesota
Association of
Wheat Growers,
North Dakota Grain
Growers Association,
South Dakota Wheat,
Inc., and the
Minnesota Barley
Growers Association.
Three words sum up why more spring wheat is grown in the Northern Plains than winter wheat: sub-zero temperatures. Get past the weather though, and winter wheat can hold an advantage over spring wheat for several reasons, including a higher yield potential, more efficient labor and machinery use, and a jump on weed competition, particularly wild oats.
Well-developed winter wheat is less likely to suffer from early season moisture stress than spring-planted small grains, since a well-developed root system enables the winter wheat crop to use sub-soil moisture.
Earlier crop development also helps in avoiding some disease and insect pressure. Winter wheat is no more resistant to scab than spring wheat, however, with a three week developmental advantage it may avoid late infection periods that will affect spring wheat. Orange wheat blossom midge only lay eggs in developing heads between head emergence and flowering. Flowering in winter wheat will be complete before the midge emerge and they will not be a problem.
Well-established winter wheat is more competitive with summer annual weeds than spring cereal grains, resulting in less dependence on chemical weed control. A healthy stand of winter wheat has good ground cover which shades the soil and acts as a strong competitive force against weed growth. For example, wild oats is rarely a problem in vigorous winter wheat fields.
Planting and fertilizing the crop in the fall lightens spring planting work loads. Since winter wheat will be ready for harvest two to three weeks before spring wheat the harvest work load is also spread out. Spreading out planting and harvest provide more efficient use of machinery.
Surviving our winters
Winter survival is the most critical factor in successfully producing a winter wheat crop in the Northern Plains. Winter kill is more of a concern from cold-warm-cold cycles and the crop breaking dormancy too soon rather than extreme cold. Cultural practices that help ensure winter survival are those that provide snow cover to maintain warmer soil temperatures in the crown area, just above the plant's root system. NDSU research indicates that a minimum of 3 inches of snow cover is necessary to prevent winterkill due to low temperatures. While three inches of snow is sufficient protection during most of our winters, 4 to 6 inches will further reduce the extent of crown injury and increase stand survival.
Several methods can be used to enhance snow cover. Winter wheat can be no-till seeded directly into flax, barley, mustard, sunflower, or other standing crop residues left to catch the snow. Seeding into wheat or durum stubble will increase the risk of some diseases, but even this practice is often preferred to seeding into clean-tilled fields, particularly in more arid areas where disease is less of a problem, since the stubble will enhance moisture conservation and protection from cold weather.
To avoid a "green bridge" for movement of wheat streak mosaic virus, volunteer wheat and grass weeds should be controlled two weeks prior to planting. Grain should be left at least 6 inches tall to obtain the minimum snow cover required. Hoe drills, which permit deeper seed placement and trap snow in furrows over the seed row, are highly recommended for bare fallow, stubble mulch or chemical fallow fields to improve winter survival.
Stands of winter wheat are often reduced due to winter injury. Don't be hasty to destroy these stands. It may be mid April, or later, before recovery is evident. Remember winter wheat will readily tiller, stands of 8-10 plants per square foot will produce very good yields.
Seeding recommendations
The recommended seeding dates for winter wheat are September 10 to September 30 in the southern half of North Dakota and September 1 to September 15 in northern regions. Planting after the recommended dates may reduce winter survival and grain yields and also delay maturity of the succeeding crop. Planting prior to the recommended date unnecessarily depletes soil moisture reserves, increases risk of disease and may reduce winter survival.
Winter wheat should be seeded at a rate of 1,000,000 viable seeds per acre or about 80 pounds per acre. Higher seeding rates are suggested for late seeding or for poor seedbed conditions.
Only the most winterhardy varieties available should be considered when growing winter wheat in North Dakota. Of the current varieties, Roughrider, Agassiz, Seward and Elkhorn possess the best combination of winterhardiness and yield. See NDSU Extension circular A-574 or the North Dakota Small Grains web page http://www.ag.ndsu.nodak.edu/aginfo/smgrains, for detailed agronomic information on available winter wheat varieties.
Fertilizer applications for winter wheat should be based on soil tests and yield expectations. Winter wheat's nitrogen need in the fall is low and does not exceed the rate that can safely be applied in the drill row at seeding time. Nitrogen applications on snow are not recommended. Snow compaction under wheel tracks destroys snow insulation properties and results in winterkill beneath the track. Movement of N offsite is also a problem on deeply frozen soils when snow melts in the spring.
Phosphorus aids overwinter survival by stimulating root growth and fall tillering. The secondary root system that develops with tillering is essential for a healthy deep-rooted plant capable of withstanding stress. While important, the contribution of phosphorus to overwinter survival is secondary to varietal hardiness and soil temperatures at the growing point in the plant crown.
Additional information is available in NDSU Extension publications: Fertilizing hard red spring wheat, durum, winter wheat and rye, SF-712; Winter Wheat Production in North Dakota, EB-33; The North Dakota fertilizer hand book, EB-65. These can be obtained by calling (701) 231-7882, or by contacting your local county extension agent before 9 a.m. or after 6:30 p.m. for optimal treatment results.
Estimating stored bushels
Whether grain is stored in square or rectangular buildings, round bins, or triangular or conical piles, you can easily estimate the number of bushels. All you need to know are the following formulas, from the Minnesota Extension Service. To calculate bushels: One cubic foot holds approximately 0.7786 Bu. of grain- any grain. Simply multiply the volume of grain in cubic feet by 0.7786. See the examples below. The formulas will not be accurate to a single bushel, but they will give you a good estimate of the number of bushels stored in a shed, bin or pile without having to count each truckload.
Square and rectangular bins:
Measure the length (L), width (W) and average height (H) in feet of the grain. You may wish to level a section of the pile to obtain a more accurate measurement. The formula is: L x W x H = Volume. Example: 25 x 12 x 8 = 2,400 cubic feet. Bushels: 2,400 cubic feet x 0.7786 = 1,869 Bu.
Round bins:
Measure the diameter (D) and height of the bin. The formula is D x D x H x 0.785 = Volume. Example: 24 x 24 x 18 x 0.785 = 8,138.88 cubic feet. Bushels: 8,139 cubic feet x 0.7786 = 6,337 Bu.
Triangular pile:
Measure the length, width and height of the pile. The formula is L x W x H x 0.5 = Volume. Example: 25 x 25 x 7 x 0.5 = 2,187.50 cubic feet. Bushels: 2,187 cubic feet x 0.7786 = 1,702 Bu.
Conical pile:
Measure the total height and diameter of the pile. The formula is D x D x H x 0.262 = Volume. Example: 20 x 20 x 8 x 0.262 = 838.40 cubic feet. Bushels: 838 cubic feet x 0.7786 = 652 Bu.