Research HighlightsImproving Profitability, Reducing SCN with a Double-Crop System
By Barb Baylor Anderson
A lack of best management practices has limited yield potential with double-crop soybeans in much of Illinois in the past. But new strategies have recently been shown to increase yield and help reduce soybean cyst nematode (SCN) infestations at the same time.
“Yield and profitability of double-crop systems can indeed increase with better management practices and adapted varieties. This also allows the double-crop system to succeed farther north in the state,” says Jason Bond, Southern Illinois University plant pathologist and principal investigator for relevant research funded by the Illinois Soybean Association checkoff program.
Double-cropping soybeans behind wheat has traditionally been a popular rotation in southern Illinois and other parts of the Midwest and Southeast. While the double-crop system is well established, it has faced challenges in recent years because of high yield and seemingly greater profitability of corn versus low yield and prices of wheat. More wheat discounts at the elevator and low double-crop soybean yields further contributed to waning enthusiasm for the system.
“We have been able to show that the wheat/soybean double-crop rotation is now more economically viable and sustainably valuable,” says Bond.
Research shows advances in breeding have created earlier maturing wheat lines, and better grain drying technologies provide for wheat harvest to occur at higher moistures. Consequently, farmers can plant soybeans more quickly and increase yield up to one bushel per acre per day.
In a typical Illinois double-crop system, corn harvest is followed by planting winter wheat in the fall. The wheat is harvested the next spring followed by planting soybeans. Harvesting three crops across two seasons can generate more revenue than two crops alone.
Bond says another benefit of a wheat/soybean double-crop rotation is a significant reduction in SCN egg counts in wheat. He has proven wheat straw reduces the SCN threat to soybeans.
Bond’s research also made the following discoveries to support the rotation:
- Tillage did not impact SCN presence.
- SCN egg counts were reduced 33 percent in plots with wheat residue compared to non-wheat residue plots. Differences were detected in the counts taken after soybean harvest.
Additional research by Bond and the late Mike Plummer, Illinois Extension specialist, found:
- SCN populations were also reduced by about 25 percent in cereal rye and ryegrass.
- Soybean yield increased by 10–12 bushels per acre.
- Soil physical and chemical properties improved with the rotation.
ISA featured more details about the research and management recommendations for farmers in its Double-Crop Rotation Guide. Farmers interested in applying the management advice supported by this research can find the document at: https://www.soybeanresearchdata.com/download.aspx?file=Progress5File&name=53700_2019_ISA_Double_Crop_Guide_FINAL_082919.pdf.
Images provide by Crop Protection Network and others cited accordingly from Southern Illinois University Carbondale school of Ag.
This project was funded by the soybean checkoff. To find research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.