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
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on August 26, 2022. The information contained within may not be the most current and accurate depending on when it is accessed.
- Associate Professor
- Extension Cropping Systems Specialist