Research Exploring the Benefit of Cover Crops in Continuous Soybeans

In recent years, cover crops have gained popularity as a sustainable tool to use for enhancing soil health and plant performance in crop rotation sequences. Planting crops like grasses, legumes and brassicas between growing seasons provides year-round ground cover, helping to reduce wind erosion and water runoff, suppress weed populations, provide additional grazing feedstock and even additional dollars.

Now, research is being conducted to see how cover crops could affect a continuous soybean system. Since a major concern with continuous soy is lower yields due to lack of biodiversity and risk of disease and insect damage, researchers are looking to see if integrating cover crops could provide rotational benefits that would help to mitigate some of these issues and, in turn, improve soybean yield.

Although a continuous soy system is not typically recommended, it is still a fairly common practice in Ohio. According to Dr. Laura Lindsey, associate professor in the Department of Horticulture and Crop Science at The Ohio State University, more farmers started to plant continuous soy for the economic benefits, but there are many disease and insect concerns associated with the system.

In her checkoff-funded study, which launched in 2018, Dr. Lindsey is looking to provide greater clarity on the effect of cover crop planting date and termination timing on soybean yield in a continuous system. In comparing the performance of a soybean field after a rye:oat cover crop to a field without a cover crop, Dr. Lindsey will also analyze the impact of cover crops on pests and diseases.

“This is a new area for us,” said Dr. Lindsey. “We are doing research to see if a grass cover crop, specifically a rye:oat mix, improves yield of continuous soybeans. We are also looking at slugs, soybean cyst nematode, diseases and insects.”

When planning a cover crop strategy for continuous soy, a few different considerations should be taken into account.

“In continuous soybeans, we are mostly interested in a non-legume cover crop, such as rye or oats,” said Dr. Lindsey. “Leguminous cover crops, such as clover, can be an alternative host for soybean cyst nematode, which is not good in a continuous soy system.”

In addition to choosing the right type, timing of cover crop planting is also important. In general, cover crops work well after soybeans since the grain is usually harvested in mid- to late September, leaving up to two months of growing potential for a cover crop planted after harvest. However, because maximizing the cover crop’s growing time is so important, it may be necessary to consider other soybean varieties.

“Farmers may want to consider planting a soybean variety with an earlier relative maturity to allow for timely cover crop planting. Timely termination of the cover crop in the spring is also important,” advised Dr. Lindsey.

When the research project is completed in 2020, Dr. Lindsey and her team will publish recommendations for cover crops in continuous soybean production. Ohio’s soybean growers will also gain a better general understanding of the rye:oat cover crop and its impacts on yield, pests and diseases.

Looking to incorporate cover crops on your farm? Reference these expert steps for getting started and these new policy changes for federal cover crop assistance.