Crimson clover, cereal rye and hairy vetch used as a green manure cover crop for sweet corn.
Drought conditions and subsequent water shortages may have forced us to cut back on our vegetable gardening this summer, but rather than leave beds completely unused this is a good opportunity to prepare them for fall, winter and spring use by cover cropping.
Cover crops, also called green manures are a way to build soil fertility by adding organic matter back to the soil. Deep rooting crops such as alfalfa help break up hardpan and bring minerals up where, when decomposed, they can be taken up by subsequent crops. The roots left deep in the soil add organic matter farther down than even plowing can go. They protect unused areas by shading soil from heavy rain, drying sun, erosion and compaction.
Legumes (alfalfa, peas, beans, clovers, vetch, lupine) have a symbiotic relationship with soil bacteria; bacteria provide legumes with access to the nitrogen in the air, while the roots provide nutrition to the bacteria. The nitrogen is stored in nodules on the roots and remains in the soil for other crops to use. In tests, hairy vetch sown in fall and turned under before planting tomatoes increased yields 45% over those using black plastic mulch. It also enabled the plants to produce longer into the season. Hairy vetch not only fixes nitrogen but smothers weeds and improves the soils ability to retain water. It is also more drought tolerant than other vetches.
Grasses (wheat, rye, oats, barley, triticale, sorghum) and buckwheat add carbon and build structure, improving soil texture and tilth. Wheat, rye, barley and oats are used to increase potassium. Buckwheat converts insoluble phosphorus into a more available form and can be used to control annual and perennial weeds. It grows in soils with poor fertility and after germination does not require much water. The flowers attract beneficials and provide a late summer nectar source for bees.
Choose cover crops according to your goals: annual (short term, temporary) or perennial (long term plans such as preparing an orchard) and nitrogen fixing or non-nitrogen fixing.
Over the long term, planting a variety of cover crops increases the diversity of life in the soil as each plant attracts a different community of soil organisms. Soil organisms consume much more carbon than nitrogen, so farmers typically use a blend with 10–40% being non-legume. Look for Soil Building Mixes such as these from Peaceful Valley http://www.groworganic.com/catalogsearch/result/?q=soil+builder+mix&x=0&y=0
Chop and turn under cover crops with a shovel or rototiller before seeds set and allow about a month for soil bacteria, microorganisms and worms to decompose it before planting/transplanting or cut the top growth and use it to provide nitrogen for carbon heavy compost heaps. Under-sow clovers about a month after crops are established to have a bed of green manure already growing when the crop is harvested and the remains composted.
References:
Four Season Harvest by Eliot Coleman
Gaia's Garden by Toby Hememway
The Complete Compost Gardening Guide by Pleasant & Martin
From: SeedsOfChange.com
Alfalfa - Medicago Sativa Legumes
This herbaceous perennial typically lives 7- 10 years, although significant soil benefits can be realized in 3 years. Do not plant if crop must be turned into the soil unless than 3 years after planting. Forms a deep tap root and hence very drought tolerant. Very effective for fixing nitrogen, improving soil structure and drainage.
Bell Beans - Vicia faba Annual legume
Small-seeded fava bean rapidly builds biomass and fixes nitrogen. Sown early- to mid-fall fro spring cutting in Mediterranean climates, early spring for late summer cutting in continental climates. Loosens soils, and attracts beneficials upon flowering. Commonly mixed with vetch and oats or rye.
Crimson Clover - Trifolium incarnatum
Winter annual legume, planted in late summer, grows rapidly during the fall. After winter dormancy, it resumes growth in the spring, producing brilliant red flowers in mid-spring. Attracts bees and many other beneficial insects, fixes over 200 lb/acre of nitrogen, and provides an excellent ground cover when sown with oats, triticale, or rye.
Medium Red Clover - Trifolium incarnatum
Vigorous extremely adaptable legume loosens subsoil, releases phosphorus and potassium, suppresses weeds, hosts beneficials and is a good forage.
Austrian Winter Pea - Pisum sativum
The Austrian variety is usually fall planted except in extremely cold climates where it is spring planted. Its viney growth habit provides excellent erosion control. The Speckled Field variety is spring planted as soon as the ground can be worked. It has an erect growth habit and is traditionally grown with oats. Yields 4000-5000 lb/acre dry matter and 150 lb/acre nitrogen.
Speckled Field Pea - Pisum sativum
The Austrian variety is usually fall planted except in extremely cold climates where it is spring planted. Its viney growth habit provides excellent erosion control. The Speckled Field variety is spring planted as soon as the ground can be worked. It has an erect growth habit and is traditionally grown with oat. Yields 4000-5000 lb/acre dry matter and 150 lb/acre nitrogen.
Soybean - Glycine max
Summer-sown legume fixes large amounts of nitrogen, suppresses weeds, and aerates topsoil. Mix with buckwheat for thicker ground cover. Harvest/ incorporate in 45-75 days. Great soil conditioner before fall greens.
Yellow Blossom Sweet Clover - Melilotus officianlis
This spring-sown biennial legume produces a strong, deep taproot that loosens subsoil and reduces soil hardpan problems. Blossoms attract honeybees and beneficial predatory wasps. In early summer of its second year the plant attains a height of 4 to 6 feet. Tolerates water-logged, saline, alkaline, and low-fertility soils. Adds 80-100 lb/acre nitrogen and 2000-3500 lb/acre dry matter. Legume.
Hairy Vetch - Vicia villosa
Extremely cold-tolerant, adaptable and vigorous winter annual legume. Plant in late summer to early fall. Slow to establish, but very prolific spring growth once soil warms up. Dense, viny growth habit, 2-3 feet high. It can attain greater height when supported by rye/oats/triticale. Contributes 80-250 lb/acre nitrogen and 3000-5000 lb/acre dry matter.
Spring Barley - Hordeum Vulgare
Spring planted, rapidly maturing, cereal grain suppresses weeds, prevents erosion, scavenges nutrients, adds organic metter and loosens topsoil. Incorporate before seed head emergence for rapid decomposition in time for warm weather crops.
Buckwheat - Fagopyrum esculentum
This rapid growing, broadleaf, summer annual is a great smother crop for weeds. It flowers in 5-6 weeks and grows 3-6 ft tall. Good for building organic matter and increasing calcium and phosphorous availability. Plant spring through summer. Non-legume.
Botanical Interests package info: Family: Polygonaceae, includes rhubarb, sheep sorrel & knotweed. 2’ to 4’ tall, 6” to 12” wide. Can be tilled under, cut off at soil level and left as surface mulch or added to compost pile. Used as human (kasha) and animal food.
Hulless Oats - Avena nuda
This fibrous-rooted, erect, annual grass grows quickly in cool, moist conditions to 3 feet tall. When planted in cold climates it produces 2000-4000 lb/acre dry matter, then dies during winter, creating a thick mulch mat into which spring crops can be planted. Fall plantings in mild climates survive the winter, yield 6000-8000 lb/acre dry matter. Spring planting is suitable in all climates. Produces oats without a thick hull, easy process for home use, while Grey Oats are more productive. Non-legume.
Spring Oats - Avena sativa
This fibrous-rooted, erect, annual grass grows in cool, moist conditions to 3ft Planted in cold climates produces 2000-4000 lb/acre dry matter, dies during the winter, creating a thick mulch mat into which spring crops can be planted. Fall plantings in mild climates survive winter, yield 6000-8000 lb/acre dry matter. Spring planting suitable in all climates. Excellent to plant with hairy vetch, peas and fava beans. Non-legume.
Sorghum-Sudangrass - Sorghum bicolor x Sorghum bicolorvar.sudanese
6-10 ft. Tender annual
Warm-season hybrid annual grass is unmatched for producing vast amounts of organic matter on low fertility soils. Sow late spring for late summer/ early fall harvest 50-90 days later. Aerates top-and subsoil. Suppresses weeds and soil nematode pests.
Winter Rye - Secale cereale
This is the most cold-hardy and productive annual grass and it tolerates a wide range of soil conditions. Plant any time from early to late fall. Germinates and grows quickly to a height of 4-5 feet. Its fibrous roots markedly improve soil structure. Commonly grown with peas or vetch to provide structural support. Non-legume.
Spring Triticale - Triticum durum X Secale cereale
Triticale is a genetic cross (not a hybrid) of durum wheat and rye. The grain has similar characteristics to wheat, while the plant has the overall vigor and winter-hardiness of rye. Although this very fast growing variety is usually spring-planted, it may also be planted in fall except where winters are extremely severe. For best results, turn under when it reaches 8 to 12 inches tall. Non-Legume
From: Ghorganics.com
ALFALFA: Perennial that roots deeply. Fixes the soil with nitrogen, accumulates iron, magnesium, phosphorous and potassium. Withstands droughts with it's long taproot and can improve just about any soil! Alfalfa has the ability to break up hard clay soil and can even send its' roots through rocks! Now that is a tenacious plant! Alfalfa is practically pest and disease free. It needs only natural rainfall to survive.
BEANS: All bean enrich the soil with nitrogen fixed form the air, improving the conditions for whatever crop you plant after the beans are finished. In general they are good company for carrots, celery, chards, corn, eggplant, peas, potatoes, brassicas, beets, radish, strawberry and cucumbers. Beans are great for heavy nitrogen users like corn and grain plants because the nitrogren used up by the corn and grains are replaced at the end of the season when the bean plants die back. French Haricot beans, sweet corn and melons are a good combo. Summer savory deters bean beetles and improves growth and flavor. Keep beans away from the alliums. Growing tip: Do not allow beans to mature on the plant, or it will stop producing, and do not pick beans or cultivate when they are wet, or it will spread viral diseases.
BUCKWHEAT: (Member of the family Polygonaceae) Accumulates calcium and can be grown as an excellent cover crop aka green manure. Buckwheat’s shallow white blossoms attract beneficial insects that control or parasitize aphids, mites and other pests. The beneficials it attracts include the following: hover flies (Syrphidae), predatory wasps, minute pirate bugs, insidious flower bugs, tachinid flies and lady beetles. Flowering may start within three weeks of planting and continue for up to 10 weeks. Buckwheat will take up phosphorus and some minor nutrients that are otherwise unavailable to plants. These nutrients are released as the residue of the buckwheat breaks down and are then available for later crops. The fine roots makes topsoil loose and friable with only minimal tillage.
CLOVER: Long used as a green manure and plant companion and is especially good to plant under grapevines. Attracts many beneficials. Useful planted around apple trees to attract predators of the woolly aphid. Clover interplanted with cabbage has been shown to reduce the native cabbage aphid and cabbageworm populations by interfering with the colonization of the pests and increasing the number of predator ground beetles.
SOYBEANS: They add nitrogen to the soil making them a good companion to corn. They repel chinch bugs and Japanese beetles. Why not try soybeans, they are good for you. They are many tasty ways to prepare them.
