Posted on

Planting Cover Crops for Nutrient Density

Introducing: Cover Crops

Much like any all-star band or sports team, nutrient-dense food has a hugely diverse cast of characters working behind the scenes to ensure every performance is tip top. In nature, this sort of happens automatically, billions of years of ecological evolution has ensured it. Visit a healthy wild grassland ecosystem like you might find here in Southern Michigan, and you will be hard pressed to find bare soil. In natural ecosystems, nutrients are cycled and harbored by plant and soil life. That’s what we want to replicate here on our farm – healthy, diverse plants, and healthy, diverse soil.

Introducing: cover crops! Cover crops are rarely seen or discussed at your local farmer’s markets, but at our farm, a successful nutrient-dense harvest doesn’t happen without them. Let’s dig right in!

What is a Cover Crop?

When we investigate the root system of our cover crop, we see a rich, healthy biological system.
When we investigate the root system of our cover crop, we see a rich, healthy biological system.

Cover crops can vary widely in species and types, and as a result have a wide variety of uses and applications that all contribute to the end result of rich, nutrient-dense soil (and food!). Peas, oats, clover, radish, wheat and other types of grasses / legumes can all be used as cover crops, and provide varying benefits.

  1. Provide soil surface armor – In those hot, late summer months, the high noon sun can really deliver a beating to your plant’s roots. Soil is dark, and dark things absorb a lot of heat. It’s not unheard of to have soil surface temperatures at 130°F+. That’s a killer for your plants. Cover crops can act as a ‘living mulch’ and help to shade them from the sun, keep more moisture in the soil and prevent erosion in heavy rain storms.
  2. Build soil aggregates – Plants take in energy from the sun through photosynthesis, and send a lot of it down into their root system. This fuels nutrient cycling and feeds all of the life that’s present in the soil. Your vegetables included! Keeping a living root system in the soil at all times will aid in the soil’s ability to hold onto essential nutrients and provides a buffer against soil acidification.
  3. Pest management – In planting a wide diversity of life on our farm, we provide many homes for insects. Some of those are pests that will feast on our plants, but most of them are predators that will feast on the pests. It is said that for every species of pest killed by chemical pesticides, 1700 neutral or beneficial species are also removed from the ecosystem. This leads to a slew of other harmful side-effects, as you might expect. We want to avoid that, and invite all of this diversity to live here in harmony with us! We provide them with food and habitat, they will return the favor by contributing to our soil biology and keeping our vegetables safe from harm.
  4. Build soil organic matter – Without abundant organic matter, you don’t have soil, you have dirt – and you can’t grow nutrient-dense food in dirt. When we ‘harvest’ our cover crops (by tilling them into the soil), we are feeding all of the wonderful biology that’s happening in our soil. Worms, fungi, bacteria, protozoa, arthropods, nematodes, we have love for all of the creepy crawlies! We need to feed the soil before the soil feeds us.
  5. Provide for pollinators – We like bees. Planting cover crops specifically for bees and other pollinators helps to make sure that our fruits and vegetables get pollinated during the growing season. We want to provide habitat and food for pollinators, because without them, we don’t have food!

Selecting Cover Crops

Clover, a legume, sequesters nitrogen from the air (free!) and cycles it into the soil, making it available for our vegetables.
Clover, a legume, sequesters nitrogen from the air (free!) and cycles it into the soil, making it available for our vegetables.

When selecting cover crops to plant, first observe and test your local soil, and once you’ve determined what is lacking, whether it be organic matter, aeration, pest control, carbon / nitrogen, you can then make a determination about which plants are going to correct for those issues.

If, for example, you were lacking organic matter, you might plant grasses to till under and provide food for the life in the soil. If you have problems with compaction, something with large tubers (Daikon Radish) to break up the soil would be more for you. It’s all about filling your specific needs! For more on cover crops, we recommend this guide to cover cropping by SARE.

“When we first started Soil Friends, we had 10 acres of land and we knew we wanted something planted on all 10 acres. We planted oats and peas, which are a great combination for adding the nitrogen we needed to the soil.” ~ Ben Martin

Article and photos by Mike McCormick