Get an edge on 1999 rotation planning

By Dr. Michael Peel
NDSU Extension Small Grains Specialist

Home

E-Mail

Back

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.

et an edge on the 1999 growing season by beginning your production

There is a tremendous interest in alternative crops, and that won’t change in 1999. But there are rotational considerations to keep in mind. I have talked about crop rotations before but I think it is important enough to cover a few points again. Rotating to a different crop such as wheat on barley ground usually results in higher grain yields when compared to continuous cropping of wheat. Even greater benefits are obtained by rotating two distinctly unrelated crops, such as a small grain and a legume or another broadleaf like flax or sunflower.

Beneficial effects that can be obtained from a well planned crop rotation include: reduced weed, insect and disease problems; beneficial residual herbicide carryover; improved soil fertility; improvements in soil tilth and aggregate stability; and soil water management to name a few.

Pest control, particularly weed control, frequently requires large inputs. Rotations can be used to cause shifts in weed populations. Populations of certain weed species can be suppressed by competition from the crop raised or by the selective use of herbicides. Wild mustard populations can be reduced by selective treatment in small grains grown in rotation with row crops. Grass weed populations, often a problem in small grains, can be reduced by the use of the appropriate herbicide in the previous row crop.

Herbicides can have both beneficial and harmful residual effects on the next crop. Therefore, planning the correct sequence of herbicide use together with crop selection has become a necessary part of rotation management. See Circular W-253, North Dakota Weed Control Guide, for specific herbicides and their potential for carryover injury on a subsequent crop.

Crop rotation has tremendous potential for reducing and often preventing the transmission of disease. Disease pressures change with changing environmental conditions. Most farmers who grew wheat and barley in rotation with broadleaf crops during the past years will testify that the incidence and severity of scab was greatly reduced. Furthermore, crop rotation is the most feasible way to control white mold in potatoes, dry beans, and sunflowers, all crops favorable for production in rotation with small grains.

Insect pests of small grains which can be controlled entirely or in part by rotations include orange blossom wheat midge, wheat stem sawfly, wheat stem maggot, and hessian fly. Insects such as corn borer, sunflower seed and stem weevil, and many others readily migrate to nearby or distant fields. Therefore, only partial control can be obtained by rotation. However, increasing field isolation from fields seeded to the same crop the previous year will often increase the effectiveness of crop rotation as an insect control method.

Legume crops such as dry bean, soybean, and alfalfa improve the soil fertility level because of their nitrogen fixation ability. Nitrogen provided through rotation will reduce the amount of commercial fertilizer needed. Soil testing should be used to provide the information needed to augment nitrogen credits from rotational crops.

A good rotation will be beneficial to all the crops involved, and will require a long-term commitment to realize all the benefits. However, rotation need not be viewed as so rigid that crop substitutions are not possible. The best rotational plan involves thoughtful considerations, but will allow substitutions to respond to changing markets.

For more detailed rotational information, see NDSU Extension bulletin "Crop Rotations for Increased Productivity," (EB-48). Contact your county extension agent for this bulletin. He or she is also a good sounding board for rotational choices, and will tell you what has — or hasn’t —worked for other producers in your area.M