Crop rotations are nothing new for farmers. Swapping between corn and soybeans in a regular yearly pattern has been a staple for many operations.
But continued research has emphasized the importance of rotations, and some agronomists are encouraging producers to look beyond the typical cash crops.
The most talked-about benefits of a crop rotation surround breaking weed and disease cycles, but a study showed it can also save on nitrogen applications.
“Our long-term study in eastern Nebraska showed that crop rotation had more agronomic and soil benefits compared to (nitrogen) alone,” said Susan Wagner, biological science lab technician with the USDA in a report for the University of Nebraska. “Nitrogen use, while beneficial, was no substitute for using crop rotation.”
Soil health was the other major beneficiary found in the eastern Nebraska long-term study originally published in 2021. The study showed diverse crop rotations including plants such as sorghum, soybeans and clover create more biomass, allow for more root growth and improve soil water retention.
Rotations also improved long-term yield stability during the time of their research and in the two years since it was published, noting that losses during a drought season were decreased by 14-90%.
In addition to creating a more stable yield floor, there were additional benefits to the year-end harvest long-term.
“Rotating crops increased yields similar to nitrogen even with no fertilizer use,” the report said. “The sequence of the rotation also affected outcomes.”
Adding sorghum tended to have even more yield benefits compared to a normal corn-soybean rotation.
One of the major pests affected by a rotation is soybean cyst nematode, a continual problem among soybean fields in the Midwest. The pests struggle to survive over a corn year.
The additional residue created in a rotation can mean a little more work or additional inputs needed to break it down, but that can be built into a rotation, said Seth Neave, a soybean specialist with the University of Minnesota.
“It’s a real benefit to have that organic matter, but it also takes considerable energy to deal with chopping or getting it incorporated it into the soil,” he said. “Having that soybean year, a low biomass year, can break things up a bit.”
Using the soybean rotation can be beneficial, particularly for those who may want to fit corn twice into a three-year rotation. The breakdown of corn residue will use up nitrogen in the soil, while soybeans will add nitrogen to the soil throughout the year.
Continuous corn is likely to drag yield down year over year. When combined with the additional costs of fertilizer, it can bring down profitability.