As harvest season finishes, it is time to think about keeping your soil alive, protected and nutritious. This is best achieved through a technique known as cover cropping. Cover crops are traditionally made up of Nitrogen fixing plants called legumes such as beans, peas and clovers *. Nitrogen fixing plants house rhizobium bacteria in their root nodes. Rhizobium is able to convert atmospheric N2 into a plant-usable form, ammonium (NH3 + H+ → NH4+), using the enzyme nitrogenase.
Besides the obvious benefit of fixing plant available N, many other wonderful things occur when you cover crop. Living soil does best when it has a continued relationship with plants. Roots create structure and help hold and protect top soil. In many ways roots are the hub for soil life. Mycorrhiza fungi only grow in relation with with plant roots creating a mutualistic exchange. Beneficial bacteria thrive in greater balance when roots are present. The place where these relationships occur is called the rhizoshpere, the narrow region of soil that is directly influenced by plant secretions. Beneficial organisms feed on sloughed off plant cells as well as proteins and sugars released by the roots known as exudates. Plants are able to play an active role in tailoring balance in soil biology by favoring the organisms it prefers with its exudate food. The plant will feed the microbes that can best mineralize the nutrients it needs. This exchange promotes diversity and balance rewarding many types of organisms with specialized functions to unlock soil nutrition. When you cover crop you allow the natural cycle and economy of your soil biology to thrive in the way nature evolved to. The living top soil will be protected from the sun by the plant foliage and the roots will aid in the growth of a healthy soil food web. Your soil biology will return to a state of balance being highly benefical when you are ready to plant in the spring. By mulching the cover crop back into the soil you preserve the bio-diversity and soil structure you developed all winter long. Tilling will break up all the wonderful soil fungi that developed, harm worms and create unbalanced bacterial spikes. Tilling can do a good job of breaking apart and mixing soil, air and materials. At Humboldt Seed Organization we believe tilling is only appropriate to initially break up compacted soil while mixing in amendments and compost high in organic matter and biology. To mulch you can simply add some compost or chicken manure evenly all over your cover crop. Then cover the bed with cardboard and stomp it down. It is best to do this in between the end of winter and the beginning of spring so you will be ready to plant by late spring. Once the whole bed is covered, the cover crop plants will start to decompose, feeding the soil biology. The mycorrhiza will still be present on the roots and will be able to spore out into the near soil. Bacteria and soil fungus will eat the the nitrogen fixing roots, preserving the plant available N in the soil. Tilling could release much of this N back into the atmosphere. Soil fungi mycelium will remain undisturbed maintaining a well structured and balanced soil food web. Worms will eat and thrive undisturbed leaving behind their plant nutritious castings. Super soils are living soils, you must protect and feed the life within it so they can do the same for your plants. *There are many options to research. I recommend visiting your local feed store to see if they offer a good mix for your area or doing some informed online shopping. Humboldt Seed Organization = Quality First