Research HighlightsSoybean Double-Crop Systems Can Be Improved with Earlier Maturing Wheat Varieties
In this article, you’ll find details on:
- An Illinois researcher is exploring wheat varieties to improve productivity in a double-crop soybean and wheat system
- Earlier maturing wheat varieties allows for soybeans to be planted sooner, possibly improving yield of both crops
- The research project also explores consistency in wheat varieties across the industry to improve variety classification
By Carol Brown
Farmers who manage two cash crops in a single season need to know how to dance. The art of planting and harvesting both wheat and soybeans requires dancing with partners such as time, weather and crop varieties. Scientists researching wheat and soybeans continue to seek the best combinations of these two crops so farmers can reap the best yields for both.
“In Illinois, especially in the southern region, farmers who grow wheat and double-crop soybeans find this combination is the most profitable over single-season soybeans or wheat,” says Jessica Rutkoski, assistant professor and wheat breeder at the University of Illinois Urbana-Champaign. “It’s a tricky balance to successfully plant and harvest both crops in a timely manner.”
Rutkoski is looking at developing and refining wheat varieties that will mature earlier in order for soybeans to be planted in an appropriate time for their success. Supported by checkoff funding from the Illinois Soybean Association, her research project is in its second year. The overall project goal is to identify wheat varieties that are higher yielding, ready to harvest earlier and are less prone to spring freeze damage.
“In double-crop soybeans, there’s a strong relationship between planting date and yield,” she says. “Farmers can lose about a half-bushel of soybeans per acre for every day that’s delayed in their planting. Getting the soybeans planted earlier in the season impacts yield and therefore profitability. Developing earlier maturing wheat varieties will advance the planting date of the double-crop soybeans and the possibility of increased yield.”
In southern Illinois, wheat is harvested between the mid-June and early July, with soybeans planted immediately afterward. Rutkoski says that longer maturity group soybeans are recommended in a double crop system so plants can establish enough biomass prior to flowering, but that also comes with a risk for frost damage.
“Some farmers have tweaked their soybean maturity group to a slightly shorter season variety so they can mature before a damaging frost in the fall,” she comments. “With this project, we’re focusing on wheat maturity as well as yield. Ideally, we want both soybean and wheat crops to avoid freeze damage.”
One of the possible consequences of selecting an early maturity wheat variety is the plant could come out of winter dormancy too soon, exposing it to freezing temperatures, which can affect yield.
“The amount of damage from a hard freeze depends on what developmental stage the wheat is in when exposed,” she explains. “If the plant is exposed to cold in the early reproductive phase, or jointing, a hard freeze can kill the tillers. But the plant can allocate resources to other tillers and compensate by filling the grains they do have. However, there will likely be an effect on yield. We are identifying which varieties start jointing a little later to help reduce the risk of damage.”
Rutkoski is testing different varieties in research plots in both southern Illinois as well as plots near Urbana. Exposing the varieties to more environments helps uncover their vulnerabilities, she says, and more accurate data can be recorded. She and her team are collecting data on wheat varieties and their maturity timing in both geographic locations so farmers can compare varieties and choose the best fit in their system. The data are included in the official state variety testing report.
“Compared to the soybean industry, wheat maturity groupings are not as unified or consistent between different companies or sources of genetics,” she says. “Wheat is classified in groups such as ultra early, very early, early, full season and so on. How these classifications are made varies across companies. With our trials and variety testing report, growers can compare the yields of varieties that mature at the same time, or look at the highest yielding varieties and identify which of these are the earliest maturing.”
Another part of the research project is helping seed companies screen their new wheat material. Companies can enter up to five wheat varieties in development into Rutkoski’s trials at no cost, and her team will evaluate when the plants begin jointing as well as yield and maturity date.
Rutkoski and her team are helping provide a source of consistent data and identifying wheat varieties that mature earlier while avoiding frost damage. Farmers who double-crop soybeans will benefit by knowing which wheat varieties to select in combination with soybeans for maximum productivity and profitability for both crops.
Other Resources:
How Can the Profitability of Double Crop Wheat and Soybeans Be Improved? – YouTube video featuring Rutkoski
Illinois Wheat Variety Testing Report
Improving Yield in Double-Cropped Soybeans – SRIN article
Double-crop Soybeans After Wheat: A Review – Kansas State University Fact Sheet
Published: Mar 3, 2025
The materials on SRIN were funded with checkoff dollars from United Soybean Board and the North Central Soybean Research Program. To find checkoff funded research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.
