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Homestead Reflections: Early Season Cover Crops Continued

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This article comes from the NOFA/Massachusetts 2018 April Issue Newsletter

By Sharon Gensler, Soil Carbon Outreach Coordinator

Cover crops 12” tall, 4 weeks from emergence 

Last week when it was 60+ degrees and the drumming of woodpeckers filled the air, it felt like it was going to be an early spring. Now that our second Nor’easter has covered the bare ground with over a foot of snow, and a third is predicted for tomorrow, I’m thinking, “nope, still winter”.  However, we gardeners know that at some point we will be able to get our hands in the soil and begin a new season of growing.

As promised, this article is the second in an on-going series about the value of and the “how-to” of using cover crops (CC) and no-till growing methods, in the home garden. I am hoping to provide you, a month in advance, the information needed to begin your cover-cropping journey. See the first installment in the March newsletter.

Last month, I talked about carbon sequestration and the importance of improving soil health through gardening practices. Increasing the types and numbers of soil organisms and microorganisms creates an intricate web of biologically active soil life. This biological soil web is like a spider web, intricate, beneficial, all parts delicately joined together to form a whole. If one part is damaged, the whole web is impacted. Looking at soil under a microscope, one can see these intricacies, especially those of the fungal hyphae and mycelium.

We are at the tip of the iceberg when it comes to understanding our soil and these inter-relationships. In our temperate climate, fungi are the predominate cellulose decomposers and thrive on woody ligneous material, often found in a good organic mulch of straw, hay, wood chips, or other mature plant stalks. Their mycelium is a vast transportation and communication system, enabling plants to ”request” a certain needed mineral and have it delivered to its roots. Fungi also help plants boost their immune systems, helping defend against pests and diseases.  This network of mycelium surrounds and penetrates plant roots and grows considerable distances beyond those of the plant.

As gardeners, one way to encourage this beneficial relationship is to practice no-till or minimal-till methods. Every time the soil is plowed, rototilled, or turned over, this network is damaged or destroyed, depriving our plants of these benefits. In addition to keeping our soil profile in tact, no-till improves soil texture and increases water retention, air penetration and erosion control. Another advantage is that dormant weed seeds are kept deeper in the soil preventing them from sprouting.

So, when preparing the soil for planting, how do we keep soil disturbance to a minimum?

  • Gently move your winter mulch back enough to plant your seeds or transplants, only disturbing the soil as little as needed to plant and cover.
  • Wherever possible, keep soil between plants/rows covered with mulch or a cover crop.
  • If soil is compacted, use a broadfork or garden spade to lightly “fluff” or aerate, but not turn, the soil. Over time, by not walking on your garden soil, using no-till and CC’s this will become less needed as your soil becomes increasingly more healthy and friable.

Fungal hyphae & mycelium PhotoIf you didn’t have an over-wintering mulch, and now have a bed of baby weeds. Try solarizing the bed to prepare it for planting. Solarization traps the sun’s radiant energy killing unwanted vegetation.

  • Spread lightweight clear plastic over the bed.
  • Weigh down the edges.
  • Do this on a sunny day so heat builds-up.
  • Leave on 24 hours (48 maximum) to kill weeds; more time will damage soil microorganisms.

How about for a bed with bigger and/or more abundant weeds? Try occultation; a method that prevents the sun’s rays from reaching the soil, trapping warmth and moisture, encouraging weed seeds to germinate and sprout into a darkened “unfriendly” environment, where they die and become food for worms and microbes.

  • Cover the bed with an opaque barrier (e.g.: tarp, black plastic, cardboard).
  • Weigh down the edges.
  • Leave covered for 3-6 weeks or as long as necessary.
  • Will not totally break down large amounts of plant residue or persistent perennial weeds.

Use the Lasagna Method as a way to create new garden beds without turning or preparing existing soil. This technique is good over sod, and particularly for overgrown beds. I used it right on top of stumps (cut close to soil level) to create soil in a formerly wooded area.

  • Lay down large pieces of cardboard on designated area. Make sure to overlap so all is fully covered.
  • Add layers of organic matter: rotted hay, shredded leaves, manure, compost, etc, with the top layer being straw or wood chips to help keep other layers from drying out.
  • Keep watered, moist but not sopping.
  • This will create fantastic soil; worms and other microorganisms love the cardboard and other organic material.
  • After six months you can plant directly into the bed.
  • Plant sooner by making planting holes and filling with compost/topsoil.

And of course mulching is another no-till technique that shouldn’t be overlooked. Use biodegradable materials: rotted hay, straw, wood chips, shredded leaves, cover crop cuttings, burlap, etc.

  • Allows for moisture penetration but helps prevent evaporation.
  • Suppresses weeds.
  • Prevents erosion.
  • Moderates soil temperature.
  • Constantly decomposes, feeding microbes and worms, and eventually becomes soil.

What follows is a brief word about weeds (which is a whole topic by itself and will be saved until another day). In general, I try not to look at them as the enemy. They can tell us a lot about our garden’s health and needs. Many can also be eaten or used as medicine. As bio-accumulators, they pull minerals from the subsoil, which eventually becomes available to our veggies. However, some are in the way or about to spread too many seed and need to be removed. Don’t pull them out which would disrupt the soil profile, rather cut them off at, or just below the soil line leaving the root in the soil to decompose, feeding those microbes and becoming air and water pathways deep into the soil.

Some of us love our tillers and tractors, so it may be hard at first to even contemplate no-till. I grew up driving an old 1940s Allis Chalmer on our family farm and have lusted after a little Kubota.  Now I’m grateful that neither our pocketbook nor our homestead terrain would accommodate a tractor.  We’ve reaped the benefits of no-till for over 35 years without realizing the science behind our practices. Hopefully, understanding the benefits of healthy soil will make it easier for you to transition. Start small, do a trial. Think of some of the other advantages, like no more expenses for the equipment, (gas, repairs, time for maintenance) plus no more breathing and covering your veggies with stinky gas fumes all while growing more nutrient dense food and sequestering carbon.

I also want to tell you my cover crop plans for April. It could still be cold and even snowy, so I only want to seed some of my most cold tolerant CC’s like oats, peas and forage radish.  I can’t give a specific planting date, as timing is dependent on air and soil temperature and accessibility (snow covered, water-logged, etc), which is a factor of your particular location and changes each year. For me, some years I’m able to plant early in the month and others much later.

As I discussed last month, I’ve already planned my garden and know which beds I will plant in early CC’s. These will be areas that will stay in CC’s all year and those that I will eventually need for another crop a bit later in the season.

Soil fissures caused by freezing temperaturesFor the most part, I will either “frost-seed” or sow directly through my over wintered mulch. Frost seeding makes use of the fissures created in the soil by overnight freezing and daytime thawing. Gently sprinkle seed on top of the soil early in the day when the ground is still frozen. They will be incorporated/self-planted by the action of the soil heaving up and down. This works on bare soil or on thinly mulched beds where the temperature can reach the soil enough to cause this effect.

To sow through mulch that is around 2-3” deep, sprinkle the seeds on top, and then use a rake to shuffle the seeds through the mulch so that they have contact with the soil. If the mulch isn’t too thick, the oats peas and radish will emerge through the organic materials and cover the bed. 

The cool air and soil temperatures of early spring may cause some seeds to rot and germination will take longer than those sown in warmer conditions. Oat & pea seed on fissured soilSo increase the amount of seeds sown, and in about 10 days the plants will emerge and you will have a very early CC growing, photosynthesizing and improving your soil. Remember, like any seed, they need to be watered and kept moist until germination.

Next month we’ll continue with ideas for early summer cover cropping and soil improvement. Until then, happy spring and happy growing!

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