When to terminate cereal rye
After a winter full of great discussions, it's clear there are a lot of farmers with cereal in their fields who will be managing that cover crop this spring. So, here are a few pointers to make sure everyone has a plan. These are just guidelines and it needs to be said that Risk Management Agency guidelines require cereal rye to be terminated in advance of planting a cash crop.
The first trick to managing cereal rye is to know when to terminate in the spring based on moisture use. Cereal rye will grow quickly, which can be good or bad. If conditions are wet, cereal rye can move moisture throughout the soil profile via transpiration and infiltration down root channels into the soil. In this case, let the cereal rye grow and reap the benefits of trafficability.
If conditions are dry and cereal rye is growing on a high clay soil, you need to make a tough decision. If the soil is drying too much and there isn't rain in the forecast prior to planting, then consider termination. If the cereal rye is on a high clay soil, it's drying out but you do see a rain in the forecast, you may take the chance and let it grow.
Whatever you decide, cereal rye (dead or living) at planting has built aggregation in the soil and the root mass will help hold up equipment. If cereal rye is on a sandy soil, monitor the moisture content closely. In most cases, cereal rye will need to be terminated early to avoid drying the seed bed too much prior to planting.
Decisions also need to be made based on the next crop in rotation. If you are planting soybean on the field with cereal rye, you have flexibility to terminate prior to or at planting depending on moisture. Always use a full rate of herbicide. If planting corn on the field with cereal rye, terminate 14 days in advance of planting corn. I have heard from multiple farmers that they have lost yield when planting corn directly into a living cereal rye cover crop. There's also a ton of university research saying "don't do this." If you decide to plant wheat on a field where you have cereal rye, think again. Even when cereal rye is terminated prior to planting wheat, Marisol Berti, a NDSU forage and cover crop researcher, has seen a yield hit on wheat. We aren't sure about cereal rye before edibles, sunflower or other crops. When in doubt, consider early termination.
A last tip — if you get nervous about having cereal rye in your field, do not use tillage to terminate it. Tilling cereal rye commits you to at least four more passes because of the large root ball. Herbicide for termination is the best approach. Strip tilling into cereal rye in the spring can also be difficult, so hopefully you got your strips into the cereal rye in the fall.
A favorite phrase I heard this winter came from Allie Marks, a crop consultant with Centrol — "Cover crops are not a crock pot. You don't just set it and forget it."
We continue to learn more each year, but hopefully this is a good start.