Using cover crops to ensure soil health

Nature hates bare soil. She will do whatever she can to cover it and you may not like what she plants.
I recently read a book that indicated we know more about life in the ocean than we do about life in the soil on which we walk. There is an extremely diverse ecosystem in the soil. There are more microorganisms (microbes) in a teaspoon of healthy soil than there are people on the earth. These microbes include bacteria, yeasts, algae, microscopic insects, nematodes, earthworms, macroscopic insects, mites and fungi. There are many microbes that scientists are still trying to figure out how to classify.

These microbes need food and shelter. Some, like earthworms and macroscopic insects, feed on the organic matter left after a crop is harvested. A large portion of the microbe food comes from the plants themselves. In a healthy environment, plants produce more carbohydrates than they need for growth. The excess carbohydrates are translocated down to and exuded from the roots, directly feeding the microbes.

Cover crops are more than just a buzzword. Use of cover crops is one of the five principles of soil health. It is a way to provide more food to the soil ecosystem for a longer period of time.

What are some of the benefits you can get from planting cover crops?

• Reduced soil erosion resulting in cleaner surface water
• Reduced nutrient leaching resulting in cleaner aquifer water
• Greater water-holding capacity of the soil resulting in drought resistance
• Reduced flooding due to slowing rainfall runoff and increased water-holding capacity
• Increased soil structure stability
• Improved nutrient efficiency because it stays where you put it and releases slowly
• Reduced soil compaction
• Improved weed control
• Habitat for beneficial insects and spiders
• Disease suppression
• Increase soil organic carbon
• Enhance the various nutrient cycles
• Nitrogen fixation with legumes
• Dry out waterlogged ground
• Improved cation exchange capacity
• Carbon sequestration in the soil

Some of the potential issues with cover crops include:

• It does take more time
• Cost of seeds and terminating the crop
• May be difficult to incorporate
• May increase insect some pests
• Some cover crops may reduce vegetable seed germination if not enough time allowed after the cover crop

You will get greater benefit if you have a mix of several different types of plants. Grasses add biomass and soil stability. Legumes add nitrogen. Daikon radishes pull lower nutrients closer to the surface, store nitrogen and punch holes through compacted layers. Some mustards help reduce some soil-borne diseases and pests.

Incorporating cover crops into your garden may require some adjustment to how you normally do things. Unfortunately, there has not been a lot of research done for home gardeners in eastern Idaho. You need to decide what you want to accomplish with your cover crops—increase organic matter, reduce need for applied fertilizers, improve soil structure? Even if you just plant a mix of the seeds you have left over from this spring you will have living roots in the soil. This will help keep the soil biology alive and functioning.

It may take two or three years before you see significant improvement to your soil. There is not enough room to completely cover the topic. If you would like to explore cover crops more and experiment with improving your garden soil, check out these websites:

UMD.EDU-Cover Crops Gardens
UMN.EDU-Managing Soil and Nutrients
USDA