Planting for the winter

Swing by the campus gardens to check out the nitrogen nodules on these cowpeas!

Swing by the campus gardens to check out the nitrogen nodules on these cowpeas!

By Marykate Glenn, Edible Campus Gardens Coordinator

The last big rainstorm of the fall season felt like it had quenched a thirst that had been building for weeks. I enjoyed it all the more, because I had just seeded our fall cover crop by the light of the moon (and university halogen lights) the night before. Cover crop is a broad term for any variety of plants grown to replenish nutrients and improve the condition of the soil.  When I saw the forecast for rain three days out, I jump-started the germination process for the cover crop seeds –the winter rye, oats, vetch, peas, and bean seeds—by  soaking them overnight. By the following evening they had imbibed enough water to triple in volume, and I scattered them in the dark over the raised beds and raked the seed into the soil. When the rain fell the next day, the seeds were ready and waiting in the earth. I felt an extra buzz of excitement on behalf of the soil, as the thunderclouds roiled in the sky, and the rains plummeted to earth that day. Just in the nick of time the rain watered it, and the crops have the necessary amount of time to develop before the cold of winter.

Our cover crop germinated in the days after the rain, and is now two to three inches tall! It’s on its way to establishing strong root systems to hold the soil intact before the arrival of snow and freezing temperatures. The cover crop roots will also provide comfortable habitat for soil microbes, fungi, and other organisms through the freezing months of winter. When left bare, soil can quickly lose its biodiversity and fertility, which is why cover cropping a garden before winter is so important.

Cover cropping can also be done in spring or even summer. In fact, a lot of growers start a leguminous cover crop (like peas or vetch) as soon as the soil can be worked in spring. Because with the help of rhizobacteria, a legume has the special ability to fix nitrogen from the air into nodules on its roots. Observant growers are watchful for the optimum timing to mow down the cover crop and work it back into the soil. Maximizing the amount of nitrogen returned to the soil means mowing when the nitrogen nodules have formed and the plant is about to flower, but has not yet produced seed. Seed production depletes most of the stored nitrogen, so by mowing cover crop  back before that happens, more nitrogen goes to the soil as the plant matter breaks down. With the extra nitrogen in the soil your next vegetable crops like tomatoes, peppers, or melons planted in late spring will be happy and healthy.

Ryegrass will out compete most weeds, and is an excellent non-legume cover crop.

Ryegrass will out compete most weeds, and is an excellent non-legume cover crop.

Growing your own nitrogen, through the cover cropping process, might not seem too exciting to gardeners who are short on space or are striving to produce the largest volume of food possible. Admittedly, devoting growing space to cover cropping can feel like a loss of edible vegetable and fruit crops. But over the long term, cover cropping increases the health and structure of the soil. As a result edible crops are more robust, disease resistant, and less dependent on nutrient inputs (i.e. less money spent on fertilizers).

The balancing act of devoting enough gardening space to replenish the soil and to produce edible crops we all love to eat is a great microcosm of global resource use. When there’s a negligence of replenishing, renewing, and distributing the resources humans use, we find ourselves facing the symptoms of resource monopolization: displacement, famine, water shortages, resource wars. Experiencing the link between soil conditions and the food we eat helps us to recognize that our survival depends on protecting the health and accessibility of the resources that sustain our lives. In small ways and big ways this connection helps me to exercise that “buzz of excitement” when the rain is coming, and I know I’ve participated in making something good for the earth, for myself, and for those who will be here when I’m gone.

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