Jan./Feb. 1998
Planning Crop Rotations
for 1998 and Beyond
By Michael D. Peel, NDSU Extension Small Grains Specialist
Library
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.
The greatest benefits are obtained by rotating distinctly unrelated crops such as a small grain following a legume or other broad leaf crop. Trials at Fargo evaluating wheat yields when grown in rotation after barley, flax, soybeans and sunflowers show yield increases of 4, 7, 14, and 9 bu/A respectively (NDSU data).
Serious problems with scab in the region for the past several years make the benefits of rotations extremely attractive. Common hosts to Fusarium, the scab causing organism, include wheat, barley, durum and corn residue. Including a one or two year break between these crops will reduce the likelihood of scab. Wheat grown in rotation with wheat not only increases the chance of severe scab infections the following year but also tan spot and bacterial blight, both controllable by rotation.
The potential for rotations to provide long term benefits to wheat producers will depend on dedication to a rotation. It is tempting to respond to high market prices and plant a crop that doesn't fit in the rotation; while this may have short-term economic benefits it destroys potential rotational benefits. A long-term plan of what will be grown on a particular field, that includes multiple options for a given year, can be designed that will reduce disease and increase productivity. A rotation should be devised to allow some crop flexibility, but once in place it is important that variations in crops are such that they do not disrupt rotational benefits.
Designing your rotation
The challenge comes in identifying crops with the greatest potential to grow in rotation in a particular region. Table 1 (see bottom of page) includes four groups of crops which can be used in designing a rotation. The crops are grouped based on their susceptibility to disease. For this reason crops in a particular group should not follow each other in rotation. This is of greatest concern where disease problems are the most prevalent.
Crops in the table are designated as either cool season or warm season. Generally the cool season crops are planted and harvested earlier than the warm season crops. Including both in a rotation will spread out planting and harvest work loads.
The broad leaf crops that are adapted for production in our area are not susceptible to scab, making them attractive to include in rotation with wheat. One viable rotation for the northeastern portion of North Dakota may include "year 1 - wheat, year 2 - canola, year 3 - barley, year 4 - Flax". This includes fours years of cropping with four crops. The advantage being a year break between each small grain crop and three years between any two crops. This not only reduces the probability of scab on the small grain but reduces the likelihood of sclerotinia on canola.
Both wheat and barley are from the same crop group and one could be substituted for the other, or another crop from group I, in either the first or third year. Likewise a crop from group III could be substituted for canola in year two and a crop from group IV could be substituted for flax in year four.
Some of the crops are not viable options for particular regions depending on environmental conditions. While soybeans and corn are quite productive in southeast N.D., moisture becomes a limiting factor as you move west, decreasing the productivity of these crops.
Remember these factors when making rotational decisions:
1) No two crops from the same group should follow each other in consecutive years;
2) Small grains should not follow corn;
3) Including a legume in the rotation will provide a nitrogen benefit to a succeeding grass crop (sugar beets should not follow a legume);
4) Including both warm and cool season crops in a rotation will spread out planting and harvest dates. Additionally, when soil moisture is a limiting factor, alternating a full-season crop with a short-season crop will conserve soil moisture.
Equally important when planning a rotation is to consider the potential for control of insect pests, available markets for a crop, and the potential for herbicide residue and its effect on a subsequent crop in the rotation.
Grains Magazine January 1998