When planting cover crops, there are many options, such as drilling, broadcasting, interseeding, or overseeding seeding. The accessibility to equipment and labor available are often deciding factors.
Aerial application of cover crops has become a method that farmers have started to utilize to give them the advantage of early application. By applying earlier in the year, farmers can see better growth out of winter kill species and better overwintering of winter hardy cover crops.
“Cash crop maturity and canopy cover, along with soil moisture all impact how successful your seeding application will be,” said Abigail Peterson, the Southern Illinois Field Manager.
When applying cover crop seed into a standing soybean crop, farmers need to evaluate plant stages before flying on the seed. The main goal is to target when the leaves are turning yellow before leaf drop. By spreading on the seed before leaf drop, farmers get better seed to soil contact and give the seed a better moisture bed when the leaves fall. There is some concern that the soybean leaves dropping will form a mat of material that will smother the seeds. Adding something like oats to the mix will help aid in pushing up through that residue to help other smaller seeds, like rape, to emerge. Beans planted in 30 inch rows rather than 15 inch rows may show improved establishment due to more light getting to the soil surface.
Another important aspect to a successful aerial application is (of course) the weather and soil conditions. Having moisture in the soil before application helps the seeds to start germinating rather than applying to a dry seed bed. A rain after application also helps to get those seeds germinating and improves contact with the soil.
When thinking about what cover crop to use, start with addressing your cover crop goals. Peterson recommended an annual rye, oats, radish and clover mix. In most areas of Illinois, try getting this mix on before September 15th. The annual rye and clover are what we hope to overwinter, the oats will help the smaller seeds succeed while adding a “buffer” to help protect the less winter hardy seeds. Unfortunately, I haven’t observed much success with the radishes getting substantial growth with aerial seeding in 2018 or 2019. Trying something like a rape or clover mix with a grass instead of radishes if you cannot meet the September fly-on date. Make sure to consult your aerial applicator for seeding rate recommendations, aerial application will be different from drilling a cover crop.
One of the biggest challenges of aerial application is getting a good stand. While most crops go directly into the soil, aerial applications are scattered on the soil surface which can lead to less consistency in the stand. A preventative measure that can create a big impact is enrolling the assistance of an experienced pilot. This can help to ensure that the seed is spread within the perimeter of the field at a consistent rate across the field.
One main issue in 2019 was the delayed harvest, which led to a continued shading of the cover crop trying to establish behind the cash crop. That delay can lead to lighter stands and less root penetration.
The key takeaway according to Peterson is to “be mindful of the year you’re in and the best method to get something established.”
Aerial application of oats, radish, annual ryegrass flown on September 26th in central Illinois (photo taken October 10).
Cover crop flown on the second week of September in south central Illinois. Notice the substantial growth of radishes in the areas of the field where there was no corn growth. (photos taken November 7)