Down With Cover Crop!
Sometimes it feels like we bully cover crop on this farm; building it up only to tear it down — akin to the low self-esteemed mongers that ravage middle schools everywhere.
But our chopping up of green manure is an act of love, as is the way we till it in, building soil with organic matter in an attempt to restore fertility to this farm rather than deplete it through exhaustive, industrial methods that are found elsewhere.
We just got finished tilling in the overwintered cover crops planted last fall, and they are breaking down in the soil as we speak. We plant a good deal of vetch and rye in the fall — which we grow together consistently through the winter, as rye is a unparralled achiever in the tall- growth category, depositing lush amounts of green material to break down in our soil each spring as long as we get to it early enough, tilling boot-high stands before the grain’s seed pods start to form and the plant shifts from being primarily nitrogenous in nature to wielding a composition that is heavier on the carbon end of the scale.
Carbon is good to us in the soil — as are humus, lignin and the simple microbial life that comes from allowing nearly anything at all to decompose in the soil — but let’s be honest, nitrogen is even better, which is why we rush to get our cover crop tilled before the plants run away from us and start to dry down in the field. Most of the vegetable crops that we grow love nitrogen, conventional farmers douse it on their fields by the truckload full of petroleum-based, synthetic fertilizers, and we are not at all above the stuff, either. But at Island Meadow, we add nitrogen gently, using organic compounds and relying heavily on cover crops and compost to build the fertility of our soil.
Vetch is the perfect companion to our rye. While rye takes off early in the fall, creating a good canopy and root material to prevent erosion and mineral leaching through the saturated winters that we know well and somehow come to love in the Pacific Northwest, vetch really shines come spring by climbing the tall rye strands (which look very similar to grass) and reaching for the sky once the spring equinox passes and our days begin to stretch out to sanguine lengths. And vetch hails from the pea family, therefore fixing nitrogen in our soil in a way that no other plant family can. It’s almost magical.
In a nutshell, Rhizobium bacteria live on the roots of plants related to peas, like vetch — the fabacea. These bacteria allow pea-family plants (clover, fava beans, vetch, peas, and others) to pull nitrogen from the air that is unavailable to any other plants. The nitrogen is drawn into purple nodes where the bacteria lives on the roots of our vetch. When we till, the bacteria, roots and nitrogen all break down in the soil leaving plant-available nitrogen in a form that was not there before.
For all these reasons, we plant cover crops again and again and again. We sow them in the fall to cover the soil through the rainy season, but we sow them in spring and summer, too. Some, like the field peas we get locally from Nash’s Organics, in Sequim, we are able to harvest and sell as food. Others, like buckwheat and phacelia that are planted in the warmer months, attract beneficial insects and pollinators that help our cash crops to thrive. But all the cover crops allow us to build our soil, which is a tendency we rely heavily upon — for if the soil we humans depend upon for food is depleted, as much of the world’s soil has been over time, we’ll be hard-pressed to find more in this late-stage of human development.
This is one facet of what makes our farm “sustainable.” At least we hope. Stay tuned…..