By Stephanie McLain
It seems like crops were just planted, and already pressure is on to put together cover crop plans. As you do this, several factors will help determine the rate of seed to use. Here’s a closer look at the cover crop seed situation for 2019 seedings.
Consider seed availability. Last year’s hurricanes and wet weather in the Southern U.S. reduced harvest amounts of summer annual cover crops and forages. Cover crops such as sorghum-sudangrass and some millets are in short supply. Also, we came into the 2019 calendar year with a limited carryover of fall cover crops such as cereal rye. These cover crops will be in tight supply.
Prevented planting acres are a factor. The ideal way to manage prevented planting acres for the growing season is to get the soil protected as soon as possible with cover crops to slow weed growth, scavenge available nutrients and get living roots in the soil to add pores and move oxygen into water-logged soils. Be aware that prevented plant acres seeded to cover crops will impact the already limited seed supply.
Pick the best seeding rate and method. How you seed cover crops will go a long way in determining how much seed you need. Higher seeding rates are needed if you fly on your cover crop compared to using a drill or precision planter. If you have prevented plant acres, a no-till drill or a seed box mounted to a vertical-tillage tool will be the best way to seed covers now. You don’t want a lot of disturbance on these soils due to potential soil compaction. Besides, weed seeds will germinate very quickly due to warmer weather and soil temperatures. Less stirring of the soil means you will be “planting” less weed seed.
Factor in your goals. Rates are also dictated by what you expect your cover crop to do. For example, if you’re new to cover crops, you might want to use a lower rate of cereal rye. This will make planting and termination easier next spring. However, you may not have full soil coverage from terminated rye residue throughout the growing season. For season-long soil coverage for weed control, moisture conservation and to maintain a consistent soil temperature, you’ll need to plant a higher rate of rye.
Plan rates knowing supply is limited. Order and obtain your cover crop seed soon. The best thing to do when you know cover crop species are limited is mix it up. Instead of just seeding cereal rye at a high rate, try a mix of oats, cereal rye and winter barley. Or if you have a prevented plant field, keep your sorghum-sudangrass to fewer than 10 pounds per acre in the mix. As a tall plant, it can take over a cover crop mix quickly. Get the benefit of having this warm-season, deep-rooted, high mycorrhizal plant in your cover crop mix, but don’t use more than you need.
No matter what cover crops you decide to use, it’s always important to pay attention to seeding rates and methods. With the tight seed supply this year, these items are especially important.
McLain is a soil health specialist with the Natural Resources Conservation Service. She writes on behalf of the Indiana Conservation Partnership.