| KEYS TO SUCCESS WITH WINTER ANNUAL FORAGES
By
Dr. Don Ball
Extension Forage Crop Agronomist
Compared to some forage crops, winter annuals are relatively easy to establish and are dependable. Yet, stand failures occur. If a livestock producer is counting heavily on winter annuals to provide pasture for his animals during the cooler months of the year, it is important to avoid problems. The following is a discussion of the most common reasons for stand failures or poor production of winter annuals.
Weather
There is no escaping the fact that in some years the weather is much more suitable for establishing and growing winter annuals than it is in others. Drought, winterkill, and the heaving of plants from the soil due to freezing and thawing are among the weather-related problems that can take a toll on winter annual forage stands.
We can’t do much about the weather, but we can do some things to make weather-related problems less likely to occur. The window of opportunity for planting winter annual forage crops is rather narrow in some years. Therefore, being ready to plant when conditions are right is often a major advantage. This includes having the proper seed on hand, having land in suitable condition, and making sure that equipment is in good working order. Delaying planting beyond the time when conditions are suitable for planting can lead to disaster.
Seed Considerations
All seed should be of species and varieties known to be adapted and productive. If mixtures of species are planted, they should be compatible with each other.
Getting a good forage stand also requires using good quality seed. Using seed of unknown quality is risky business. Purchasing seed through established seed channels is helpful because it offers the advantage of having a label that reveals germination level and other important seed quality traits. Germination tests should be run on unlabeled seed or seed held over from a previous year. Seed is a minor portion of the cost of establishing most forage crops, including winter annuals.
Legume seed should be inoculated with the proper type of inoculum. Some legume seed is preinoculated, but most winter annual legume seed needs to be inoculated just before planting. Inoculation of legume seed is a simple but important task.
Seed of some legumes such as arrowleaf clover should be scarified before planting. Problems from lack of scarification normally come from homegrown seed or farmer-to-farmer purchases. Dealer-purchased seed normally will have been scarified if needed.
Fertilization
Fertilization should be according to soil test recommendations. When planting on a prepared seedbed, it is usually best to incorporate fertilizer into the seedbed just before planting. When overseeding summer grass sods, it is best to wait until the winter annuals have emerged before applying fertilizer because this reduces the chance of stimulating competition from the summer grass.
Low Soil pH
Soil Acidity, or low soil pH, is a common reason for poor production from winter annuals. The general recommendation for good winter annual forage production is that the soil pH should be in the range of 5.8 to 6.5. Legumes tend to be particularly sensitive to acidity, but winter annual grass production can also be severely reduced.
If needed fertilizer and lime are applied, proper planting techniques are followed, and climatic conditions are favorable, germination and seedling growth should be rapid, which is important. Once seedlings have a good root system developed, their ability to withstand stresses increases considerably.
Wrong Planting Date
Planting winter annuals too early on a prepared seedbed can expose the seedlings to excessive heat; planting too early on a summer grass sod can allow the summer grass to outcompete the winter annuals. Planting too late reduces autumn and winter forage production and increases the likelihood of freeze damage and heaving.
Planting winter annuals into a prepared seedbed should be done no earlier than early September in north Alabama, early to mid-September in central Alabama, and late September in south Alabama. Overseeding winter annuals on a summer sod should normally be done in early October in north Alabama, in mid to late October in central Alabama, and in early November in south Alabama. (NOTE: These are guidelines; weather conditions and other considerations can influence planting dates somewhat.)
Wrong Seeding Rate
Seeding rate recommendations are available through Alabama County Extension offices and elsewhere. If germination or seed vigor is low or if planting conditions are particularly unfavorable, a higher seeding rate should be used. It is wasteful to use unnecessarily high amounts of seed, but with forage crops it is better to err on the high side rather than the low side.
Wrong Planting Depth
Seeding depth is critically important, so recommendations provided through Alabama County Extension offices or other credible sources should be carefully followed. Planting seed too deeply can prevent emergence or result in weak seedlings; planting too shallowly can unnecessarily expose germinating seed to harsh conditions.
As a rule of thumb, a given type of seed should be planted no deeper than eight times its diameter. When clovers or other small, dense seed are planted on a prepared seedbed, a cultipacker should be used to ensure good seed-soil contact and to firm the seedbed to prevent settling of the seed after planting.
Insects
Several species of insects can be a problem when growing winter annuals. These include crickets, which may consume young clover plants; aphids, which reduce the vigor of many species of winter annuals; and armyworms, which often attack young stands planted on a prepared seedbed in early autumn. The lesson here is that it pays to carefully inspect sods where winter annuals are to be planted and to closely monitor seedling stands.
Excessive Stubble
The most common reason for failure in overseeding winter annuals is excessive plant residue being left on the field. Research has shown that it is preferable to have summer grass stubble down to a height of one inch or less, if possible. This is especially important with small-seeded forage species such as ryegrass or clovers. Close clipping, heavy grazing, tillage, and fire are methods that can be used in various situations to reduce plant residue on the soil surface before overseeding winter annuals.
Grazing Too Early
Many a good stand of winter annuals has been severely damaged by being grazed too early. Grazing too early on a prepared seedbed planting can result in extreme hoof damage, especially if the soil is wet. In addition, if livestock are exposed to seedling forage plants before they have a good root system established, the animals may pull up the plants. Winter annuals planted on a prepared seedbed should normally be allowed to reach a height of 8 to 12 inches before grazing begins.
Conclusion
One of the advantages livestock producers in the South have is the ability to grow high-quality, productive winter annual forage crops. A few things can go wrong with winter annual plantings that have not been mentioned in this discussion, but if we could eliminate these problems, our success rate with these productive and useful species would be close to 100%.
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