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Cover cropping

Cover Crop

Why Plant a Cover Crop?

Plant a cover crop to improve soil quality and soil nutrition. Cover crops also attracts beneficial insects. A cover crop planted in the fall and tilled under in the spring is often referred to as a “green manure” crop

Benefits of planting a cover crop

  • Increases organic matter and available nitrogen
  • Increases earthworms and beneficial microorganisms
  • Decreases compaction and improves water, root, air penetration of soil
  • Provides habitat, nectar pollen for beneficial insects
  • Creates an aesthetic addition to your garden during winter dormancy

Selecting a cover crop

The choice of cover crop depends on what benefit you are hoping to achieve. If your primary benefit in a garden is the addition of nitrogen, use legumes, such as Fava beans. Nurseries also sell cover crop mixes geared to soil type and future planting goals. Check with your local nursery to see if they carry such mixes, or shop for a soil builder cover crop mix online.

Legume Seed Inoculation and Planting

Legumes work in harmony with the bacteria that lives on their roots. These bacteria take nitrogen from the air and fix it in pink root nodules. This adds nitrogen to the soil in a form that plants can absorb. To ensure good nitrogen fixation by the legume one need to use a inoculate. You need to use an inoculate that has the proper strains of bacteria. Inoculate your seeds right before planting the seeds. You can buy the inoculant at the same place where you buy your cover crop seeds. Inoculate the seeds and plant the seeds immediately. The legumes germinate and need little maintenance during the winter.

Spring Tilling of Cover Crops

The best time to till in your cover crop is when 50% of the flowers are in bloom. After tilling, the cover crop will decompose. The soil microbes will return nitrogen and other elements to the soil for the next crop. It is best to cut the cover crop in small pieces (i.e., shred) the cover crop, so it will break down faster. Shred the cover crop and as quick as possible till the cover crop into the the soil. The cover crop will lose nitrogen and carbon very rapidly if left exposed to the sun. The breakdown process will take 2 – 3 weeks.

Cover Cropping Results in Mill Valley

A Mill Valley gardener use a “Premium Soil Builder mix cover crop” and the right strain of inoculant. The cover crop:

  • Fixed the depleted nitrogen in the garden.
  • Added organic matter to the soil the spring garden.
  • Provided an excellent habitat for beneficial insects.
  • Improved garden soil
  • Reduced diseases and pests in the summer garden
  • Increased productivity in the summer garden

To Learn More:

Download Cover Cropping from UCCE Agriculture & Natural Resources

Adapted from an article by Allison Krivoruchko, Marin Master Gardener
Photo Credit: Allison Krivoruchko