Short-Term Summer Cover Crops

Legumes

Non-Legumes

• Sorghum sudangrass (Sorghum bicolor x S. sudanense) is a cross between grain sorghum and sudangrass. It is a warm-season annual grass that grows well in hot conditions and produces a large amount of biomass. Its thick root system and high biomass makes it useful for soil building. Sorghum sudangrass can reach 6-12 feet tall, but should be mowed when it reaches 2-3 feet tall to prevent it from becoming fibrous and difficult to manage. Mowing also encourages root growth. Unmowed sorghum sudangrass will winterkill but the tough residue can be difficult to manage in the spring. Brown midrib types will decompose more quickly because they have less lignin. Expect 3-4 tons of biomass addition per acre in MA. Because it is a grass, to get the most growth you will need to add nitrogen fertilizer (40-80 lbs/A), which will be cycled on to the next crop. Sorghum sudangrass is very effective at suppressing weeds and has been shown to have allelopathic and biofumigant properties useful for nematode management. Drill 35-40 lbs/A or 40-50 lbs/A broadcast.
• Phacelia (Phacelia tanacetifolia), also known as blue or purple tansy, is a good cover crop for use in rotation on vegetable farms because it is not in the same family as any major vegetable crops. This fast-growing cover crop is best to seed in mid-summer. While it does not have a deep taproot, phacelia is a wonderful soil aggregator in the top 2 inches. Beneficial insects including parasitoids and pollinators are attracted to the fuzzy purple-blue flowers. This cover crop will winterkill at 15°F. Seed at 1 lb/A drilled and 3 lb/A broadcast.
• Pearl millet (Pennisetum glaucum) or Japanese millet (Echinochloa spp.) have similar functions as summer cover crops: they grow rapidly but are easier to manage than sorghum sudangrass. They also produce less biomass than sorghum sudangrass. Both millets grow about 4-6 feet tall and have similar seeding rates. They are well-adapted to sandy and/or infertile soils and do well in the summer heat. Forage types are better adapted for soil improvement than grain types. To get the most growth, you will need to add nitrogen fertilizer (40-80 lbs/A). Pearl millet has been shown to suppress some nematodes. Forage pearl millet can make a good mulch for late-summer plantings of no-till or strip-till crops. Seed at 12-15 lbs/A drilled or 15-20 lbs/A broadcast.

• Buckwheat (Fagopyrum esculentum) is a great choice if weed suppression is your main goal. It can be sown as early as May 20, but will put on more growth if seeded after June 1st. As a broadleaf plant, it covers the ground earlier than grass cover crops, and out-competes weeds. A good stand of buckwheat attracts beneficial insects, improves soil tilth, and produces more biomass than any other cover crop in the short time it grows, but doesn’t do well if the plow layer is compacted. It scavenges phosphorus from the soil and makes it available to subsequent crops. Buckwheat does well even in low nitrogen or low phosphorous soils, without additional fertilizer. Buckwheat decomposes quickly after incorporation. Mow or incorporate when the planting begins flowering to avoid seed production and volunteers. Drill at 50 lbs/A or broadcast at 70 lbs/A.