To plant green or to plant brown? Rye cover crop termination timing before soybeans

Cereal rye (Secale cereale) has several strengths as a cover crop option. It’s relatively inexpensive and easy to kill. Rye improves soil structure, builds organic matter and helps protect against water and wind erosion. It can suppress weeds as discussed here. It’s also very winter hardy and often the only cover crop option to seed after grain corn or soybeans. However, in most cases, rye doesn’t put on much growth until the month of May.

 

 

Delaying termination up until soybean planting provides an opportunity to enhance rye’s benefits by giving it more time to grow in the spring. The question is, does planting soybeans “green” into living rye negatively impact yield? This was the motivation for a series of on-farm trials from 2017 to 2019, in which soybeans grown after early-terminated rye were compared to those “planted green” into rye.

 

There were two main treatments: early rye termination (two weeks before soybean planting) and late termination (day of planting, also referred to as “Plant Green”). Trials in 2019 also had a no-rye control treatment.