Deep Impact!

Deep Impact of Crop Rotation: Including wheat in a rotation is good for the soil

Growing red wheat isn’t just about baking bread. It’s important to include wheat in any crop rotation because it makes all other crops better. A corn-soybean rotation when prices are high is not good for long term soil health. Inevitably, the lack of diversity will reduce yields and growers won’t be able to capitalize on good prices.

Both long-term crop rotation studies at Elora and Ridgetown prove the value of diversification in cropping systems. Researchers have been reporting on the importance of crop rotation and not relying on just two crops in alternating sequence.

“Dr. Bill Deen and I have seen increases in both corn and soybean yields as the crop system becomes more diverse,” explains Dr. David Hooker of University of Guelph, Ridgetown. “Wheat has a positive impact on other crops in rotation, but it rarely gets the credit when growers compute an enterprise analysis by crop.”

Wheat in a rotation will improve the yield of all other crops through improvements primarily in soil health. It’s difficult to seed red clover in a corn-soybean rotation, but when it is underseeded to wheat, the clover will increase the yield on the following corn crop in addition to nitrogen credits. “The main reasons for including wheat in a rotation include: yield improvements, system resilience, and improved fertility,” says Dr. Hooker. “We have documented organic matter increases from a quarter to half a per cent with wheat in rotation compared to a corn-soybean rotation. It may not seem like much, but that is a big difference.”

Corn-soybean rotations do not show consistent increases in crop yield during continuous mono-cropping comparisons at Elora and Ridgetown. But in the plots where wheat has been included in the mix, positive results are measurable. At both research stations corn yields were at least +10 bu/ac higher, and soybean +5 bu/ac higher, in a corn-soybean-wheat rotation compared to a corn-soy radiation Therefore, the wheat enterprise should be credited with the increased revenues in both corn and soybean.

Furthermore, red wheat in the rotation enables a red clover cover crop, which produces approximately 70 lbs N/ac of nitrogen for the corn enterprise, which should also be credited to the wheat enterprise. Inclusion of red clover after wheat has also shown a corn yield increase of +6 bu/ac compared to no red clover underseeded into wheat; this benefit of the wheat enterprise, and several others were not included in the enterprise analysis, but should be considered.

“This is an example of a systems approach to economic management,” Dr. Hooker explains. By including wheat in a rotation, growers have a better option to underseed red clover, which is good for the soil and following crops. Wheat also gives the soil a “break” from the depletion of nutrients caused by the other crops, and it breaks up the weed and pest cycle, which can be an economic plus. Dr. Hooker suggests growers need to take a long term approach to soil management, which, as demonstrated in the long term at Elora, pays off over time.

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