Cover crops can provide significant soil health benefits ahead of corn, but growers need to carefully match species selection and management practices to their production system, according to Illinois Soil Health Specialist Jim Isermann.
While cereal rye is one of the most widely recommended cover crops before soybeans, planting it ahead of corn presents additional challenges because both crops belong to the grass family. That relationship can increase the risk of certain pests and diseases while also creating management concerns.
Cereal rye can temporarily reduce nitrogen availability if it is not terminated early enough, as the decomposing residue ties up nitrogen needed by the emerging corn crop. It also can produce compounds that suppress corn seed germination, making proper termination timing especially important.
Despite those concerns, cereal rye remains a viable option when managed correctly.
Some growers instead choose barley ahead of corn because it is generally easier to manage. Barley typically grows only 2 to 3 feet tall, compared with cereal rye, which can reach 6 feet. Its slower spring growth provides a wider window for termination before planting corn.
The tradeoff is that barley is less winter hardy than cereal rye and must be planted earlier to improve its chances of surviving through winter.
For cereal cover crops such as cereal rye, barley, wheat and triticale, terminating plants when they reach 8 to 12 inches tall generally improves control and reduces potential issues for the following corn crop.
Growers also can consider noncereal cover crops, including legumes, brassicas and annual ryegrass. These species can improve soil health while helping build nitrogen for the next corn crop. However, they typically require earlier planting dates and more intensive management. In many cases, they must be established before harvest because planting afterward is too late for successful establishment.
Isermann pointed to two growing seasons that demonstrated how weather and timing can influence cover crop performance.
In 2012, wet conditions from hurricane remnants allowed many farmers to aerial seed annual ryegrass and radishes before harvest. The cover crops established successfully, and when drought later reduced forage supplies, they provided valuable winter grazing for livestock.
In contrast, persistent wet weather in 2019 delayed termination of cereal rye ahead of soybeans, leaving many fields with plants reaching 5 to 6 feet tall. Although most growers avoided severe losses, many experienced yield reductions because of the delayed management.
Isermann said successful cover crop programs depend on selecting the appropriate species, planting at the proper time, terminating the cover crop before it becomes difficult to manage and adapting practices to changing weather conditions. With careful planning, cover crops can provide lasting agronomic benefits while reducing risks to the following corn crop.
Source: IL Corn, "Why Barley Might Beat Cereal Rye Ahead of Corn"