On July 12th ICCON was joined by Chase Brown of Brown Seed Sales in Central Illinois to discuss the considerations and mechanics of rate calculations in multi-species cover crop mixes. Chase has spent the last 10 years diving into cover crops and regenerative ag practices. In that time, he has had plenty of opportunities to learn about using cover crop mixes on his own farm and on those of his customers.
A mix of cover crops including oats, radish, and rapeseed that Chase often uses.
Chase says the biggest advantage to using multiple species in a cover crop mix is diversity. Every species is different and brings different qualities to the mix. Stimulating soil biology and providing nutrition to the cash crop is the ultimate goal. The root exudates of each species feeds that biology differently which will allow the soil to become more functional, especially with continued proper management. Diversity also increases the ability of the soil microbial communities to cycle nutrients and feed the cash crop more effectively. It also can be viewed as a risk management tool. When using multi-species mixes, some species may perform better than others based on a multitude of factors including weather, planting date, and planting method.
This mix of seven cover crop species includes a diversity of root styles, leaf styles, and upright plants. This mix serves as the primary organic fertilizer for Chase’s corn crop.
When making species selection and rate determinations, we know that farmers need to be clear about what their goals are around cover crop usage. There are also some logistical considerations that need to be taken into account. Which seeding method will be used? Some species will do well when drilled while others may need to be broadcast. For seeds that need to be planted ½-1” deep, a broadcast method is probably not a good choice. The inverse is also true. Selections can be made and tailored based on what a farm has the capacity to do.
Plant architecture and growth habits should also be considered when deciding mix rates so as not to seed one species too heavy or too light and dominate the field. Farmers should be clear about goals and understand the different heights and root structures that each species offers.
When making the final decision on how much of each species to include in a mix, Chase says “it’s part science, part intuition, part experience!” A good starting point is to consult the Midwest Cover Crop Council’s Selector Tool to find base rates to use when only one species is selected. When mixing species together, Chase says a good rule of thumb is to cut the seeding rate back for each species base on how many are in the mix. For example, with three species in a mix, each species can be run at a third of the recommended rate. From there, farmers should keep evaluating the performance of the mix and adjust ratios based on their goals and comfort level.
Chase’s full presentation can be viewed on ISAP’s Youtube channel. ICCON’s summer series, Cover Crop Cocktails, will continue in August with a presentation by Bethany Bedeker from Center of Regenerative Agriculture at University of Missouri. Bethany will discuss how cover crop mixes can address and improve specific field conditions. If you are interested in joining the Illinois Cover Crop On-Farm Network to learn about new research and hear from cover crop specialists across the Midwest, you can register for our monthly calls or join our google group by sending an email to hvanbeck@farmland.org.
