Benefits of wheat in a rotation
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
With the enthusiasm for producing ethanol from corn and biodiesel from soybeans, wheat has become the forgotten field crop. However, including wheat in a corn-soybean rotation can provide some real benefits for the quality and productive of the soil. The price of wheat makes it an economically attractive crop as well. In the 1990’s, Dick Harwood did considerable research evaluating the effects of wheat in rotation with corn and soybeans. Including wheat in the rotation was found to increase corn yields by at least 10 percent. In Michigan studies, when wheat was followed by a cover crop, such as frost seeded red clover, corn yields were always increased by at least 15 percent over continuous corn. This effect is valid for soils with low and high yield potential. The exact reasons for this enhancement in corn yield are not well understood, but are likely a combination of several effects.
A well established wheat crop provides good ground cover through the winter months to prevent wind erosion. One of the keys to improving and maintaining soil quality is to have vegetation growing in the soil for as many months of the year as possible. Growing winter wheat after soybeans or another crop and then following wheat with a cover crop makes this possible for as long as 22 months. Plant roots contribute to enhancing microbial activity, nutrient cycling and improving soil aggregation. Red clover may be frost seeded into wheat or some other cover crop may be seeded after wheat harvest to continue active rooting in the soil. The long term decomposition of wheat roots and stubble contributes to cycling of nutrients, and a legume cover crop provides nitrogen for the following corn crop. At 50 cents per pound, a 60 lb N/ acre credit is worth 30 dollars per acre. In Michigan studies, nitrogen credits have ranged from 40 to 120 lbs N/ acre. Wheat is effective in utilizing residual soil nitrogen and reducing nitrogen loss by leaching. If strategically planted, wheat can also serve as effective filter strips and wind buffer strips. The physical condition of the soil tends to be preserved during the wheat production cycle because there is minimal tillage, and trafficking is usually done at times when the soil is not as susceptible to compaction.
When sown in September or October after the harvest of soybeans, wheat breaks the cycle of pests and weeds that tend to become problems with continuous summer annual crops. The need for pesticides is generally less with wheat than summer annual crops. The period after wheat harvest provides an opportunity to control troublesome perennial weeds. Soil moisture after wheat harvest is usually favorable for sub-soiling where there is a need to loosen compact soil conditions. This is also an excellent time for establishment of cover crops if none were interseeded. Green wheat growing in the spring provides a good habitat for insect predators, such as ladybird beetles, that can then move into corn and soybean fields for controlling pest insects. An established cover crop can continue to serve a similar role throughout the summer.
Wheat in the rotation spreads the production cost and weather (growing conditions) risks across another crop and distributes farm operations on time. There is little or no demand during the critical April-May corn-soybean planting period. The post-harvest period is ideal for making lime, manure or corrective nutrient applications.
With increased emphasis on corn production, farmers need to recognize the benefits wheat can provide in improving long term corn yields. In summary, benefits from having wheat in the crop rotation include improving soil quality, cycling nutrients and providing nitrogen credit, breaking the cycle of annual and perennial weeds, protecting soil from soil erosion, distributing farming operations and providing a good return on investments. Therefore, as cropping rotations are being planned, be sure to consider wheat and its benefits.