Planning for the “summer slump?” Now is the time to consider planting summer annuals to maintain forage production during this period of the grazing season when recovery periods slow for cool season pasture perennials, such as timothy, orchardgrass, and clover.
Summer annuals are warm-season grasses typically planted in early June (now!) and can be grazed or harvested as stored feed (hay or silage) once or twice during the season, depending on the weather. Although they require hot weather and modest fertility rates, they can grow quickly outcompete weeds and develop extensive root systems that can scavenge nutrients and water that would otherwise be unavailable to most other crops.
Sudangrass, Forage Sorghum, and Sorghum-Sudangrass Hybrids
Sudangrass establishes quickly, produces a lot of biomass, and has an extensive scavenging root system. Sorghum-sudangrass hybrids, and especially brown mid-rib (BMR) varieties, have been gaining in popularity as these hybrids produce similar yields to sudangrasses yet are of higher digestibility and forage. Sudangrasses and sorghums should be seeded into soils that are about 65°F with adequate moisture at a depth of about 0.5 to 1 inch at a rate of 50 lbs. per acre. High biomass production can make curing for hay difficult. At heights above 36 inches, these grasses begin to produce seed heads, and crude protein and digestibility levels will drop dramatically. Plants should not be grazed below 10 inches if regrowth is desired. These species can contain toxic prussic acid. The following guidelines should be followed to avoid poisoning:
- Graze sorghums, sudangrasses, and hybrids when they are at least 18 inches tall.
- Do not graze plants during and shortly after drought periods when growth is severely reduced.
- Do not graze wilted plants or plants with young tillers.
- Do not graze after a non-killing frost; regrowth can be toxic.
- Do not graze after a killing frost until plant material is dry (the toxin usually dissipates within 48 hours).
- Do not graze at night when frost is likely. High levels of toxins are produced within hours after frost occurs.
- Delay feeding silage six to eight weeks following ensiling.
Millet is another warm-season grass that can be grazed or harvested as stored feed. It tends to grow more slowly than sorghum and sudangrass; however, it can tolerate more acidic soils and does not contain prussic acid. Millet should be seeded at a rate of 20 lbs. per acre via the same methods as sudangrasses. If nitrogen is to be applied, it should be done in multiple, smaller applications after grazes to avoid over-fertilization and potential problems with nitrate accumulation. Proso, foxtail, pearl and Japanese millets are the common types used for livestock feeds. Proso and foxtail millets are often ensiled as they have shorter grazing seasons and tend not to produce as much biomass as pearl and Japanese millets. Millet can be grazed when it reaches a height of about 18 inches. It should not be grazed below 10 inches if regrowth is desired.
Teff is a relatively new crop to the Northeast. It is native to Ethiopia where it is grown as a cereal crop in traditional foods. It can be grazed or harvested as stored feed. It does not have issues with prussic acid or nitrates. Teff’s thinner stems allow for faster hay curing than millet or sudangrass. It should be seeded at around 6 pounds per acre at a shallow depth of 0.25 inches as the seed is quite small; seeding deeper than 0.5 inches will likely result in very poor stand establishment. Cultipacking after seeding may be beneficial in providing adequate moisture to the seed. Teff can be grazed or harvested approximately 50 to 55 days after seeding depending on weather. Before grazing, test the stand—by pulling on a handful of the grass—to see if the roots have established enough to withstand grazing. For optimal forage production, do not graze or harvest below 5 inches as this will stunt the crop. Subsequent harvests should be possible in another 45 to 50 days after the first graze/harvest.
For information on summer annuals, see the eOrganic webinar, “Focus on Summer Annuals,” with Heather Darby and Rick Kersbergen: http://articles.extension.org/pages/68106/organic-dairy-forages:-focus-on-summer-annuals