Winter cover crops have proven they can protect soils from erosion and put organic matter into soils, but growers have worried whether the practice might also lead to reduced yields for their commercial crops.

That wasn’t the case for a three-year cover crop and wheat double cropping study conducted on soybeans by agronomists with the University of Arkansas System Division of Agriculture at experiment stations in three locations across the state.

“We did see significant differences across the cover crop treatments with our highest yield being a three-year average of 63 bushels per acre,” said Trent Roberts, associate professor and soil fertility Extension specialist with the University of Arkansas. “That followed our blend 2 which, essentially, is a 50-50 split of Austrian winter peas and black-seeded oats.”

Roberts was one of the speakers at the University’s Rice and Soybean Field Day, which was held virtually due to concerns about Covid-19. His presentation was recorded at the Pine Tree Research Station near Colt in St. Francis County where researchers have been studying cover crops for a number of years.

Study trials

The other trials in the three-year study were conducted at the Rohwer Research Station near Rohwer in southeast Arkansas’ Desha County and the Vegetable Research Substation near Kibbler in Crawford County in western Arkansas.

See more: Cover crops bringing numerical increases in soil health

“The reason we chose those locations is it gives us different environmental conditions, gives us different soils to look at and will change the way the soybean reacts to the environment and to the cover crops,” said Roberts.

Wide range of cover

The study features a wide range of cover crops, “but the key thing we wanted to do was try to compare to a traditional system that still includes tillage but does not have any type of winter cover crop treatment,” he noted. “On the other end of the spectrum we have a traditional wheat-soybean double-crop system where wheat is produced for grain and followed by soybeans.”

The latter has fallen out of favor, he said, because growers say harvesting the wheat can push soybean planting beyond the optimal planting dates for the highest soybean yields. The return on wheat is offset by the loss in returns on soybeans in the double-crop system.

“That potential for profit loss is one of the reasons we wanted to include that system in the study,” said Roberts.

Next after the cover crop treatment with Austrian winter peas and black-seeded oats at an average of 63 bushels per acre came the fallow treatment, which had no cover crop during the winter and spring months. Those plots averaged 57 bushels per acre over the three years.

“The lowest yielding treatment was the wheat-soybean double-crop system, and it came in at 53 bushels per acre,” he said. “So what you can see is the range from our highest yielding to our lowest yielding treatment was about 10 bushels per acre with our traditional producer practice coming in right at the middle of the pack.

“So we do see significant differences in soybean yields as we implement these different crop production practices with our highest yielding treatment following cover crops in rotation.”

For more information on the Rice and Soybean Field Day, visit 2021 Rice & Soybean Online Field Day (uada.edu).

Next: Tillage costs can add up in traditional soybean planting systems