Small grain crop rotations

What you need to know

  • Small grains almost always yield better following another crop than when following other small grains.

  • Rotations can control or reduce disease, insect and weed pressure.

  • Rotations can improve soil fertility and soil structure.

  • Rotations help manage available soil moisture.

  • Diversity in crops grown can spread out fieldwork and harvest time, as well as reduce risk.

Crop rotation is the order specific crops are planted on the same field. The order a small grain crop is included in a rotation can significantly impact grain yield and/or grain quality.

How to select a crop rotation

When selecting a rotation, consider the long-term viability of that rotation to reduce weed, insect and disease pressure, and its economic viability.

Always follow a well-developed plan that can be altered when necessary. Otherwise, the desired crop sequence may be interrupted and you won’t get the maximum benefits of the rotational effect.

Important questions to consider when designing a crop rotation, regardless of location are:

  • How will previous crops affect subsequent crop production?

  • Will the previous crop increase or decrease concerns? Consider several dimensions, including disease, insect, weed pressures, soil fertility and soil structure.

Research findings

Research directed toward developing crop rotation recommendations is complex to implement and difficult to interpret. This is because of the diversity of crops grown in Minnesota and North Dakota, plus the large number of potential crop sequences.

Guiding principles

However, research has established several principles to consider when creating a rotation plan. Principles include:

  • Small grains almost always yield better following another crop than when following other small grains.

  • Rotations can control or reduce disease, insect and weed pressure.

  • Rotations can improve soil fertility and soil structure.

  • Rotations help manage available soil moisture.

  • Diversity in crops grown can spread out fieldwork and harvest time, as well as reduce risk.

Yield advantages

Rotations consistently offer a yield advantage over continuous monocropping. Numerous studies have demonstrated the yield advantage of rotating small grains compared to continuous small grain cropping.

You can often trace the rotation’s yield advantage to reduced levels of diseases or insects. However, sometimes the yield advantage can’t be attributed to any known, observable factor; the crop just grows better. This is often referred to as the rotation effect.

Study results

Rotation studies in Fargo over a nine-year period showed a 40, 20 and 15 percent increase in grain yield when wheat followed soybeans, sunflowers or flax, respectively, compared to continuous wheat.

Research conducted by the Department of Agriculture’s Agricultural Research Service lab in Mandan, N.D.—where more than 100 crop combinations were grown in rotations—found spring wheat was invariably the lowest yielding when preceded by spring wheat (Table 1). Similarly, barley following barley was lower yielding than when it followed any of the other preceding crops.

This study is a rich source of information on cropping sequences, particularly for environments like south-central North Dakota. Study results are available on an interactive CD called the Crop Sequence Calculator.

Research clearly shows that, to optimize yield, don’t grow a small grain crop after a previous small grain crop of the same species.

Effects of rotation

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Potential crop rotations: Minnesota and North Dakota

Table 5 includes crops adapted for production in Minnesota and North Dakota with potential for rotations. You can maximize rotational benefits if crops from a common group don’t follow one another in a rotation. 

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Strengths and weaknesses of each rotation

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Jochum Wiersma, Extension agronomist and Joel Ransom, Extension agronomist, North Dakota State University

Acknowledgements

Adapted from “Crop rotations for increased profitability” by M.D. Peel, North Dakota State University.

Reviewed in 2018

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