|Managing Winter Annuals|
By Don Ball
The ability to grow winter annual forages such as the small grains, ryegrass, and various annual legumes to produce high-quality grazing during some of the coldest months of the year is a major advantage Alabama livestock producers have over producers in other parts of the country. In a year like this during which there is a widespread shortage of hay for wintering animals, winter annuals are of particular value.
Good production from cool-season annuals requires adequate fertility. Although initial fertilizer applications should have already been made for most plantings in 2006, a review of general recommendations should be appropriate. Phosphorous, potassium, and lime should have been applied at or near planting time according to soil test recommendations. Grass-legume mixtures planted on a prepared seedbed in early autumn should have received 60 pounds of nitrogen at planting time or soon thereafter. If the legume does not make up at least 30 percent of the ground cover or additional grass growth is needed, another 60 pounds of nitrogen should be applied in late February. Grasses grown without legumes and planted in early September on prepared land should have received 100 pounds of nitrogen per acre at or near planting time. An additional 60 pounds of N per acre should be applied in late February.
Winter annual forages overseeded on the sods of warm season grasses such as bermudagrass or bahiagrass typically need less nitrogen fertilizer than plantings made on a prepared seedbed. The reason is that overseeded stands are usually planted 4 to 6 weeks later, which means there is less time for growth between planting and cold weather that will severely limit growth, so less nitrogen fertilizer is needed (this is true for late plantings into a prepared seedbed as well).
What species are planted and location within the state makes a difference as to the amount of nitrogen needed as well. Small grains, especially rye, make more growth than ryegrass in autumn and winter. Also, the farther south one goes in Alabama, the more forage growth is likely to occur during the winter months. A “rule of thumb” when making nitrogen applications to winter annual grasses (where there is no legume present) is that about a pound of nitrogen is needed per acre for each day of good growing weather that is expected before the next application of nitrogen is to be made or grazing is to be terminated.
It is advisable to not begin grazing winter annuals until small grain seedlings are at least 8 inches tall or ryegrass is at least 6 inches tall. Overseeded ryegrass and clovers are unlikely to provide grazing until late winter, but except for very late-planted fields, grazing of small grain should be possible in late autumn. It’s also important to keep cattle off of a winter annual pasture if the soil is quite soft or during extremely muddy periods, especially when the plants are very small.
If the acreage of winter annuals available is limited and hay is short, a “limit grazing” system in which cattle are turned into the pasture for only a few hours each day is a great technique for efficiently using the forage. Livestock producers who use this system confirm that it is not as much trouble as it sounds like it would be. In this sort of system, 2 to 4 cows (or the equivalent) can be grazed per acre depending on how much additional feed the animals are receiving. Winter annual pastures will not grow in mid-winter (except possibly along the Gulf Coast), so supplemental feed will be required for several weeks in most areas of the state.
Spring growth should be grazed intensively so that the forage will be used efficiently. Keeping overseeded warm season perennial pastures grazed down in spring also minimize competition between the winter annuals and the summer grass. Ideally, winter annual pastures should not be grazed closer than 3 to 4 inches. If a pasture is not kept grazed down during the spring flush of growth, much of the forage produced will be wasted by trampling and fouling. In addition, much of the forage will be older, lower in quality, and less palatable, and any legumes in mixture will be shaded by grass and become non-productive.
Don Ball is an Extension Forage Crop Agronomist with Auburn University.