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Short-season forages provide dairy producers an excellent opportunity to supplement forage supplies when needed during specific seasons, while adding flexibility to forage production systems. The yield and nutritive value from these forages is highly dependent on management. Warm-season or cool-season annual species can fit into a double-cropping or triple cropping system, or integrated into cropping rotations, depending on length of the growing season. The options of species to use depends on the time of seeding, length of growing season, and forage production goals.
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Planting Late Spring to Early Summer
Short-season annual forages can be planted following a spring harvest of a perennial forage stand that is being discontinued due to thinning plant stand or winter injury. Annual forages can also be double-cropped after a winter cereal species harvested as forage in the spring, such as winter rye. Another option in late spring is to interseed annual forages into a winter cereal toward the end of its cycle but before it will be harvested for grain in mid-summer. Forage options for this time of year include corn silage, summer annual grasses, soybean, and brassicas.
Corn for silage can be planted later than optimal for grain production in most regions; however, later planted silage corn has increased risk should dry weather develop. Despite the risk associated with late planting, corn silage should be a top choice because with adequate rainfall, it can produce more forage with greater feeding value than most other summer annual grasses. Even without grain formation, the feeding value of corn is at least equal to that of the other summer annual grasses, and forage yields are likely to be higher.
Sudangrass, sorghum x sudangrass hybrids (Figure 1), pearl millet, and forage sorghum grow rapidly in summer and are excellent choices for planting in early summer. They are more drought tolerant than corn. When managed properly, these grasses can provide forage with good nutritive value, especially if selecting sorghum varieties with the brown-midrib trait (see “Forage Sorghum for Dairy Cattle” in this series). All these species can be planted once soil temperatures reach 60 oF (16 oC), about two weeks later than the optimal time for corn planting. Most of these grasses can be harvested multiple times and will produce a total of 3.5 to 6 tons of dry matter (DM) per acre across all harvests depending on location and growing conditions; forage sorghum is harvested once and can produce as much as 8 to 12 tons DM per acre depending on location and growing conditions,. Pearl millet is essentially free of prussic acid poisoning potential, but the sorghum species have the potential for prussic acid poisoning, which varies by species. Nitrate toxicity is possible with all summer annual grasses (including corn silage) and management steps should be taken to reduce that risk.
Mixtures of summer-annual grasses and legumes, such as field peas and soybeans, are marketed by some seed dealers. The legumes generally improve protein content but only in the first harvest because they don’t regrow after cutting. Legumes usually increase the seed cost, so consider the cost-to-benefit ratio of purchasing mixtures with legumes vs. supplementing livestock with other protein sources.
Teff is a warm-season grass that can be used for hay, silage, or pasture (Figure 1). Multiple harvests can be taken in many regions, with yields ranging from 3 to 4 tons of DM per acre in short growing seasons and up to 8 tons of DM per acre in regions with long growing seasons. Teff can tolerate both drought-stressed and waterlogged soils.
Figure1 . Teff and sorghum x sudangrass grown in research plots.
Soybean can be grown for forage, but it is difficult to dry sufficiently to make hay. Ensiling soybean also has challenges. The high concentration of fat (about 10%) in soybean inhibits bacteria in the silage, causing slow fermentation that is often incomplete. The best approach to using soybean forage is to mix 1 part soybean with 1 part or more of whole plant corn during silo filling. For silo bags, mixing is difficult so the ratio of corn to soybeans should be increased and the amount of soybeans put in the silo at one time should be small. Use of herbicide-treated soybeans for forage or hay is allowed for only a few herbicides, so check chemical labels before using herbicides on soybeans to be used for forage.
Several brassica species (e.g., turnips, rape) can be planted in late spring to early summer for late summer grazing or autumn grazing 50 to 100 days later, depending on variety and growing conditions. These species contain high moisture content, so they should be used for grazing only. Brassicas have very low fiber with high energy content and should be treated more like a concentrate than as forage in ruminant diets.
Planting Mid-Summer to Early Autumn
Mid- to late-summer forage plantings can be made after a winter cereal grain harvest or other short-season cash crops. Summer annual grasses can be planted in mid-summer, but they should be planted as soon as possible after the cash crop harvest. Small grains (e.g., oat or spring triticale) and annual/Italian ryegrass can be planted a bit later for autumn forage production. Early maturing brassica varieties can be planted in mid-summer for late autumn to early winter grazing.
When planted in late summer and assuming adequate rainfall, oat and spring triticale will yield 2 to 2.5 tons of DM/acre in the boot stage, 60 to 80 days after planting. If harvest or grazing is delayed into the heading stage, forage yields will be 3 tons of DM/acre or more. The forage will have crude protein (CP) content of 12 to 15% and neutral detergent fiber (NDF) of 38 to 50%, depending on planting date and stage of maturity at harvest. The CP content of the forage can be expected to increase by 3 to 4 percentage units when including field peas or soybeans with oats or spring triticale planted late summer. The value of this CP boost should be compared to the cost of the legume seed included in the mixture. Field peas should be inoculated with N-fixing bacteria and sown in the mixture at 70 to 90 lb/acre. Soybean seeding rates for this application are not well-defined, but perhaps should be included in the mixture at 60 to 70% of normal soybean seeding rates.
Annual or Italian ryegrass planted in late summer can also produce high quality forage for grazing late autumn to early winter, with additional forage harvests or grazing the next spring into early summer. Some varieties have better winter survival than others, so check performance trials in your region. The forage quality of annual or Italian ryegrass will be at least equal to or higher than that of the small grain forages.
Double-crop plantings can follow an early corn silage harvest (Figure 2). Spring oat, spring triticale, and annual/Italian ryegrasses are good options for this time of year. These later planting dates will produce lower yields than if planted earlier, ranging from 0.7 to 2 tons DM/acre. Harvest will be delayed into months with characteristically poor drying conditions in many regions, so grazing (Figure 3) or green chopping are better options than trying to make silage or haylage.
Figure 2. Annual ryegrass (left) and oat plus winter rye (right) planted after corn silage in central Ohio with picture taken in November.
Figure 3. Dairy heifer grazing oat plus winter rye in early December, which was planted after corn silage harvest in early September in central Ohio. In the background is annual ryegrass planted the same day.
Forage quality in autumn will be very high from annual forages planted in early autumn. Crude protein will range from 20 to 32%, NDF will be 30 to 38%, and NDF digestibility will be 75 to 85% in late autumn.
If an early spring forage harvest is desirable the following year in addition to autumn forage production, then Italian ryegrass should be used or winter triticale and/or winter rye in mixtures with oat or spring triticale. The oat or spring triticale will increase fall forage production, while winter triticale and rye will produce more forage in the spring. Italian ryegrass will produce forage in the autumn and the following spring into early summer.
Winter wheat, winter triticale, and winter rye can be planted in autumn to produce good yields of high quality forage the following spring. Wheat planting should be delayed until after the Hessian fly-safe date which varies by region. Rye will grow and mature the quickest in the spring and must be managed to avoid over-ripening. Wheat and winter triticale are easier to manage in spring because they mature later and more slowly than rye. Forage quality of these species will be excellent if harvested in the vegetative to boot stage of growth in the spring, with yields of 2 to 4 tons/acre of DM depending on harvest stage.
Seed Quality and Seeding Rates
Plant high quality seed, meaning the seed tag should show high % purity, high % germination, low % weed seed, and low % inert matter. It is also important to purchase seed of a named variety rather than seed of “variety not stated” to ensure the best opportunity for successful establishment and avoid unpleasant performance results from an unknown variety. Look for and ask the seed dealer for yield performance data from your region for the varieties being considered. Oat should be planted at 75 to 100 lb/acre and spring triticale at 90 to 110 lb/acre when seeded alone. Winter rye should be seeded at 110 lb/acre, while wheat and winter triticale should be seeded at 110 to 120 lb/acre. For mixtures of these small grains, the seeding rate of each component can be reduced to 70% of the full rate. Annual/Italian ryegrass should be planted at 20 to 25 lb/acre.
No-till planting will conserve moisture and provide firm soil conditions for either harvesting equipment or grazing animals. If weeds are present prior to planting, a burn-down application of glyphosate is an important and cost-effective weed control practice.
When planted after wheat grain harvest, oat, spring triticale, or annual ryegrass will likely require 30 to 50 lb/acre of nitrogen at planting. Manure applications can replace some or all of the N fertilizer need, depending on the amount of readily available N in the manure. Additional nitrogen will be required next spring for good production, usually 50 lb/acre of actual nitrogen in early spring and again after the first or second harvest if growing Italian ryegrass.
When planting small grains or annual/Italian ryegrass after corn silage, be aware of the potential for nitrogen carryover from the corn. Depending on the rate of nitrogen applied to the corn, additional nitrogen applications may not be advisable. Excessive nitrogen carryover from corn coupled with additional nitrogen fertilizer applied to the new plantings can result in toxic levels of nitrates in the forage produced in the autumn.
Chopping and ensiling or ensiling wet bales are the best mechanical harvest alternatives for these supplemental forages. Dry baling is a challenge, especially in the autumn, because the small grains dry about half as fast as grass hay. Ryegrasses are also slower to dry than other grasses.
For early autumn planted forage, grazing provides the most effective and affordable alternative for utilizing the forage. Strip grazing through part of the winter can be an option for dry cows or heifers. Oat plants will not die until temperatures dip to the mid 20’s 0F for several hours. Winter rye, winter triticale, and winter wheat, require colder temperatures before growth is completely halted for the winter. They survive the winter in most regions, resuming vigorous growth in early spring. Italian ryegrass is less winter hardy than the winter cereals, but newer varieties are able to survive the winter in many regions to resume growth the following spring.
Short-season annual forages offer many opportunities to produce supplemental forage within cropping systems. They can be used together in sequence, such as planting a winter cereal species for spring forage followed by a summer annual grass during the summer. They also can be incorporated between cash crops, increasing the efficiency of land use while protecting the soil that often sits idle without cover for an extended period of time between the cash crops.
The Ohio State University