At Pine Mountain we encourage all of the Grow Appalachia families to plant a cover crop when they clear off their garden in the fall. Many gardeners around the area already plant cover crops, but those that were new to using cover crops were amazed at the results they received. Many gardeners found great beauty in the early green covering and later flowering of their gardens in the spring from oats, rye, peas, clover, and vetch. One gardener had a hard growing season during 2010, and felt that her garden soil was completely worn out from years of production. She planted crimson clover and rye on her garden last fall and has seen much better production this year from her garden. She does not use fertilizer, and believes that cover crops are saving her soil!
Cover crops are usually planted in the late summer or early fall to cover the ground while food crops are not being grown. Turn the crop over using a plow or shovel during the early spring and allow the organic matter to decompose for a week to three weeks before rototilling and planting seeds. Cover crops have many benefits:
1. Improve soil quality: When the soil is allowed to lay bare during the traditional non-gardening months the soil surface seals together and water runs off during rains. Cover crops prevent this sealing of the earth and improve the soil structure. The root establishment over the winter months improves air and water infiltration into the soil, as does the decomposition of the organic matter after it is turned under. Earthworms and other soil organisms also thrive while the plants are decomposing.
2. Erosion Control: Cover crops hold the soil in place during the late fall, winter, and early spring thus reducing erosion due to wind and water coming into contact with the bare earth.
3. Increase soil fertility: Legume cover crops add nitrogen to the soil from the atmosphere due to their associations with nitrogen fixing bacteria. Non-legume cover crops can recycle excess nitrogen, phosphorus, and potassium from the previous crop to the following crop. Why not try this instead of using the synthetic N-P-K fertilizer next spring?! When cover crops are turned under and allowed to decompose they slowly release the nutrients that they have taken up. This will add some micro nutrients not usually added to the soil through traditional fertilization plans.
4. Suppress weeds: A dense stand of cover crop will reduce the amount of weeds that germinate in the fall due to shading. Some cover crops also release chemicals into the soil that will suppress other plants (weeds).
5. Insect control: Beneficial insects may be attracted to cover crops plantings, such as lady beetles or ground beetles that eat pest insects. Flowering cover crops will also attract beneficial insects
6. Subdue soil diseases and pests: Cover crops support beneficial soil microbes that can work against soil diseases and pests. Some cover crops may also produce compounds that suppress these problems.
Legumes
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Non-legumes
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Clovers
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Rye
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Hairy Vetch
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Oats
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Field Peas
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Wheat
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Soybean
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Forage Turnips
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Buckwheat
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Cover Crop
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When to Sow
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When to Turn Under
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spring or fall
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fall or spring
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spring or fall
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fall or spring
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spring or summer
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summer or fall
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late spring or summer
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summer or fall
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spring or fall
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spring, summer or fall
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fall
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spring
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Spring or summer
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spring
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Field Peas
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Spring or fall
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spring
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Forage Radish
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Summer
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Spring
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Crimson Clover: Can kill weeds if planted in early fall, especially if it is planted with oats. Clover is great at increasing the nitrogen content of your soil. Crimson clover grows fast in cool fall and spring weather. Mow down the clover and turn under after flowering (nitrogen fixation occurs then). Crop seeding rate is 10lbs per acre broadcasted. Or mix 1/3 clover and 2/3 rye grass or oats and broadcast at 25lbs per acre.
Hairy Vetch: Hairy vetch is a legume that can survive the winter. It is an excellent nitrogen fixer (maybe even better than peas!). Vetch is slow to establish, but is wonderful at suppressing weeds and improving soil quality. Some growers have found this plant to be invasive. Plant in late August through September. Mow down/turn under after flowering (nitrogen fixation occurs then). Broadcast 25-40lbs per acre.
Buckwheat: Buckwheat’s rapid growth smothers most weeds. Buckwheat fits into the “green manure” category of cover crops because of its rapid breakdown which releases nutrients for the succeeding crop and fits into a tight vegetable rotation, such as when a crop is harvested prior to mid-July and a succeeding crop is not scheduled until fall. The breakdown of buckwheat improves soil structure and moisture holding capacity. If volunteer buckwheat is harmful in the succeeding crop, then the green manure crop of buckwheat should be destroyed before a large number of seeds mature. Buckwheat will germinate at temperatures ranging from 45° to 105°F. Broadcast 70lbs per acre.
Oats: Oats are not winter hardy. Spring plant oats for a green manure. While fall plant oats and let them winter kill for a ground cover. Then turn under the oats before early spring plantings. Since oats are easily killed they work well in vegetable rotations. Oats are a great nurse crop for legumes, such as hairy vetch and peas. Broadcast 110-140 lbs per acre by itself. Broadcast 80lbs oats per acre with 40lbs vetch.
Winter Rye: Rye is a cold tolerant and can germinate in soil as cool as 34-40° F, making it a major fall-planted cover crop. Rye has a well-developed fibrous root system that reduces leaching of soil nitrogen. Plant in September through mid-October. Broadcast 85-250 lbs per acre, depending on seeding date. The later in the season you plant rye, the more seed you will need to plant. Broadcast 60lbs per acre with 15lbs clover.
Annual Ryegrass: The extensive root system of this cover crop tolerates compacted soils and makes it an effective catch crop for excess nitrogen. It can also be used as a nurse crop with fall-planted legumes such as clover. Plant in early spring through late summer. Avoid seeding this cover crop during hot, dry weather. Annual ryegrass can be interseeded between or over established vegetable crops. Broadcast seed when conditions are moist and before the canopy fills in. Plant in fall as a winter cover or as a nurse crop for clover. Broadcast 85-250 lbs per acre, depending on seeding date. The later in the season you plant rye, the more seed you will need to plant. Broadcast 60lbs per acre with 15lbs clover.
Field Peas: Field peas can be used as a spring cover crop to increase organic matter in the soil and fix nitrogen. In late summer, peas can be interseeded with oats to provide ground cover over the winter. For a spring cover crop plant in March-April. Plant with oats in late summer for winter cover. Nitrogen from the peas will aid the growth of the oats, which will frost kill and give ground cover over the winter. Broadcast 140lbs per acre. Seeding peas, oats and vetch together is a popular combination at 50lbs/140lbs/30lbs per acre respectively.
Forage Radish: Forage radish is a fall-seeded Brassica that is not winter hardy. This crop forms thick, white tap roots that can reach lengths of 8-14 inches, most of which are underground. Radishes are excellent at breaking up shallow layers of compacted soils. A thinner extension of the tap root can penetrate deeper layers of compaction. The roots die over the winter and leave channels so that the soil dries and warms up faster in the spring. Forage radishes also suppress fall weeds. Plant 4-10 weeks before first frost. Broadcast 13lbs per acre. Mustard and turnips are also popular cover crops, especially in our area.
Information about cover crops for this blog has been found at http://www.hort.cornell.edu/bjorkman/lab/covercrops/index.php
Other cover crops resources:
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