As we enter the time for aerial and broadcast overseeding of cover crops, now is a good time to think about how current weather, soil and crop conditions might affect things. First and foremost, there are parts of the state that are very dry and others that have been getting timely rains. Rainfall and soil moisture are important factors in establishing cover crops. Dry conditions, especially for overseeding situations, could cause delays with seed germination and, therefore, establishment will be less than ideal. Here are some considerations for seeding into dry conditions.
- Postpone overseeding until rain chances improve for improved odds of germination
- Consider drill seeding after harvest has occurred to achieve better seed to soil contact
- Switch to cereal rye for improving overwintering survival
Another consideration that may need to be factored in is herbicide carryover. With the start of planting being delayed and lack of mid-summer soybean canopy cover, there were some later than normal herbicide applications. If those later herbicide applications had residual activity, combined with drier weather, there could be herbicide carryover that could reduce cover crop seed germination and establishment. Some species are more tolerant (cereal rye), and others are less tolerant (radish). Use caution where residual herbicides were used and consider switching to cereal rye for successful establishment.
Spring cereal rye growth following overseeding into preharvest corn.
Relevant Resources
Considerations When Overseeding Cover Crops
Tips and Considerations for Getting Started with Cover Crops
Mark Licht Associate Professor
Dr. Mark Licht is an associate professor and extension cropping systems specialist with Iowa State University Extension and Outreach. His extension, research and teaching program is focused on how to holistically manage Iowa cropping systems to achieve productivity, profitability and en...