October 10, 2010 in Idaho Voices

Plant cover crops during fall to feed, weed plot for next year

Pat Munts
 
For more information

Overview of cover crops and green manures

• National Center for Appropriate Technology,

attra.ncat.org/attra-pub/PDF/covercrop.pdf

Sources of cover crops:

• Northwest Seed and Pet, Spokane

• Peaceful Valley Farm Supply, www.groworganic.com

• Johnny’s Seeds, www.johnnyseeds.com

For all practical purposes, we are coming to the end of the gardening season. The plants will go on until there is a killing frost, but we are losing so much heat and daylight now that the chances of getting much riper are waning. It’s time for fall cleanup.

Pulling out the spent plants is going to leave a lot of bare soil exposed to erosion, nutrient loss and invasions from enterprising weeds over the winter. An easy way to reduce all three of these issues is to plant cover crops in any of your bare vegetable beds.

Cover crops are a seed or seeds planted after the main crop is harvested and intentionally plowed under or cut down before the next crop is planted in the spring. Another name for this is green manure cropping.

Farmers use cover crops as a way to add organic matter and nutrients back into the soil and to shade out any weeds that pop up. An added benefit to covering the soil is the reduction of soil erosion by wind and water. We’ve all seen how hard it can rain and blow here, and a lot of that moving soil ends up in our streams and lakes.

Now is a good time to plant cover crops in your gardens. We’ve had some good rains to replenish the soil moisture and the soil will be warm enough to germinate seed for another month to six weeks.

To prepare your beds, remove spent plants and rake or till the soil smooth. Using a hand-crank fertilizer spreader set for the proper seed size, go over your plot twice at 90-degree angles. This spreads the seed evenly. Lightly rake the seed in and then tamp it with a rake or lawn roller and water lightly. Water lightly for a few weeks if we don’t get any rain. The crop should emerge within a couple of weeks.

Crops typically used for cover crops include cereal rye and other grains, clovers, vetch, mustards, Austrian field peas and blends of these. Grains are used to add organic material to the soil, while clovers, vetch and field peas, all legumes, will also fix nitrogen in the soil. By some measures they add enough nitrogen to the soil to replace one application later. Mustards add organic matter and, with several years of use, possibly inhibit weeds.

One challenge in our area is that a lot of cover crops will be killed in an average winter here. The killed residue, however, will continue to provide soil protection through the winter and the dead material will add organic material and nutrients when it’s turned under in the spring.

One of the best cover crop mixes for our area is a combination of cereal rye and Austrian field peas. In a mild winter with some snow cover, they are likely to survive and will continue growing in the spring until they are turned under. If they are killed, they still leave the ground covered.

Pat Munts is a Master Gardener who has gardened the same acre in Spokane Valley for 30 years. She can be reached by e-mail at pat@ inlandnwgardening.com.


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