NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
August 12, 1999
Many North Dakota producers with prevented-planting acres have tilled their fallow for the dual purpose of weed control and aeration. But if left open, those fields will be at increased risk of erosion during the upcoming winter and early spring months without the benefit of a cover crop, say two specialists with the North Dakota State University Extension Service.
Fortunately, producers have several low-cost options for cover crops, and they can use the late-August, early September period for controlling perennial weeds and establishing the cover. Another option is to plant fall-seeded cash crops.
"We usually don't have this much fallow," says Dave Franzen, extension soil scientist at NDSU. "A lot of the soils we have in the state are pretty fragile. They have very fine sands. They have high levels of carbonates, and those things contribute to movement when it's windy. We lose a lot more topsoil to wind than we do to water, although water erosion is also a possibility in some areas."
The ideal practice to maximize protection would be planting a cover crop over the entire field. Although a cover crop would use up some soil moisture this fall, the residue may keep the soil surface from warming and drying as quickly in the spring. For producers concerned that a cover crop will delay entry into their fields next spring, Franzen suggests planting strips 2 or 3 feet wide spaced about 30 feet apart. He stresses that while coarse-textured soils are the most susceptible to wind erosion, even heavier soils can erode significantly if there are no windbreaks nearby.
Wind barriers such as corn or flax strips are effective at reducing soil erosion, but producers need to make sure that these strips will not contribute to water erosion caused by spring runoff, according to Alan Ness, state conservation agronomist with the Natural Resources Conservation Service in Bismarck. Whether wind barriers or cover crops, Ness says it's likely that producers with tilled fallow will need to use some type of wind-erosion prevention because fields that receive two tillage passes are likely to contain inadequate residue amounts.
Ness says there are no longer any federal cost-share programs available for annual barriers. He adds, "Producers in this situation basically have two choices. They can let volunteer cover grow up and spray it, or plant a cover crop."
Barley, oats, mustard and canola all make effective, low-cost cover crops, as will flax, but flax seed currently is in short supply, says Duane Berglund, extension agronomist at NDSU. One advantage of using mustard or canola as cover is that these crops will lay flat after a hard freeze and provide ground cover but not catch as much snow as flax, which maintains an upright posture during the winter. Similarly, barley and oats will flatten out after a killing frost. Fields with less snow catch due to flattened cover crops should be slightly drier in the spring.
"One-fourth of the normal seeding rate for any of these crops will be enough to establish a cover," Berglund says. He adds that if producers decide to plant flax or corn strips, they should plant the barriers running perpendicular to the prevailing northwest winds.
Prior to seeding a cover crop, producers should focus on perennial weed control, Berglund says. He explains, "The timing of this strategy would be to take care of the perennial weeds in late August and then plant the cover crop."
Another option for producers would be to plant cash crops, either winter wheat or winter rye. Berglund concludes, "I can think of very few crops that have fewer inputs than winter wheat or winter rye, and rye is very competitive with all types of weeds."
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NDSU Agriculture Communication
Sources: Dave Franzen (701) 231-8884
Duane Berglund (701) 231-8135
Editor: Dean Hulse (701) 231-6136