No Bare Ground: Planning Your Cover Crops to Maximize Their Benefits
I can tell you all the reasons why it is best for my body to eat well, sleep well, and exercise, but many days, my task-oriented brain takes over and I shove self-care to the bottom of my list. Similarly, while most vegetable growers are familiar with the reasons why they should cover crop—to protect against erosion, to cycle nutrients, to fix nitrogen, to boost organic matter, to suppress weeds—it can be hard to make cover cropping a priority in the midst more pressing demands on a vegetable farm.
Plan Cover Crops in Advance
Perhaps the most critical first step in becoming a committed cover cropper is to integrate cover crops into your crop plan. This means that when you decide where your onions, potatoes, and eggplant are going, you should also decide what cover crop will immediately follow each cash crop throughout the season. Including cover crops into your crop plan also means ordering cover crop seed before the season starts, just as you do for your vegetable seeds. This is particularly important for certified organic growers since organic seed can be tough to source and may sell out quickly. Once the season begins, you are less likely to spend the time or money ordering seed. (Just remember to store it in a space secure from rodents!)
As you consider next year’s crop rotation, cover crops can play a critical role in correcting some of the issues from this season. Below are a few items to observe as you wrap up the current season and suggested cover crops for helping to balance things out:
- Make note of where this season’s weed pressure was particularly high or where you are currently seeing weeds go to seed. You will want to plant a smother cover crop on this field, and may even consider multiple successions of cover crops. To ensure the smother effect you want, your seeding rate should be slightly higher than suggested just to make sure you don’t leave a crack of light for those weeds to germinate. Also be sure to seed at a time when you are guaranteed to have good germination (like right before a gentle rainstorm). Some good candidates for fall smother crops are oats or winter rye. During the summer, buckwheat and sorghum-sudangrass (“sudax”) can suppress weeds.
- Note where you noticed nutrient deficiencies during the current season. If you are cover cropping after a heavy feeder, seed a legume. Field peas or hairy vetch are good candidates if you plan to grow on this field next year.
- Note where you applied significant amount of nutrients (including compost). You will want to plant a cover crop to “mop” up these excess nutrients—and you should get this cover crop established as soon as you can to prevent the nutrients from leaching.
- Suggested cover crops are rye (if fall or winter), oats (if late summer), or sorghum-sudangrass (if midsummer). Note that seeding a legume into a nutrient rich field doesn’t make much sense since your goal is to cycle the existing nutrients, NOT fix more nitrogen.