August 10, 2001 | By: Aimee D. Heald
LEXINGTON, KY.

Proper summer forage management extend the grazing season. University of Kentucky College of Agriculture Forage Specialist Jimmy Henning said producers should focus on two issues – properly using summer annual grasses and looking ahead to fall and winter grazing.

Sudangrass, sorghum-sudan hybrids and pearl millet will provide their first cutting around 60 days after planting,” he said. “They also require topdressing with 50 pounds of actual Nitrogen for every cutting. Their yield potential is from two to four tons of hay per acre.”

Although these summer grasses provide a quick first cutting and have good yield potential, Henning said producers should realize there could be problems with cyanide and/or nitrate poisoning.

“Prussic acid, or cyanide poisoning can occur when grazing immature sudangrasses and sorghum sudans,” he warned, “but most of the time it comes from grazing newly frosted material or the very lush young growth after the tops have been frosted. The leaves are toxic, but it will dissipate in hay.”

Henning said all summer annual grasses have a toxic potential especially where nitrate poisoning is concerned. Producers should know that high Nitrogen rates, followed by extreme drought or cloudy cool weather, is the perfect environment for nitrate poisoning.

“The plant takes up NO3-N but cannot convert it to protein,” Henning said. “It accumulates in the stalk and lower portion of the plant, and remains in the hay made from these plants.”

If in doubt, Henning recommends having the plants tested for nitrates. It will ease your mind and let you know the safety of using these grasses.

He also recommends not grazing any of the sudan or sorghum-sudan crosses (including johnsongrass) for two weeks after a frost. The cyanide will dissipate during this time.

“Practically speaking, a big concern with cyanide poisoning after frost comes from cows grazing corn fields with significant amounts of johnsgrass that we have forgotten is there,” he continued.

For more information get Extension publication AGR-88 Producing Summer Annual Grasses for Emergency for Supplemental Forage from your county Extension office.

It may seem early to be thinking about the forage supply for fall and early winter, but acting quickly now can mean significant hay savings. Stockpiling tall fescue pastures from now until late October or early November will produce high quality forage that can carry a beef herd well into the winter.

“Stockpiling is allowing a pasture to grow, while deferring grazing to a later time,” Henning said. “Although any forage can be stockpiled, tall fescue is the forage of choice because it is very high quality in the fall, and it holds this quality well after frost.”

Stockpiling is a three step process. First, animals should be removed from the fescue area to be stockpiled. Then, nitrogen fertilizer should be applied. Thirdly, this area should be allowed to grow until late October or early November before animals are put back in.

There are things you can do right now to prepare. First, identify fields that might be the best for stockpiling. Henning strongly warns that over-grazed tall fescue fields are poor candidates for stockpiling, especially when moisture is limiting.

“These fields just do not grow back very fast, even with adequate nitrogen fertilization,” he said.

Second, be ready to apply nitrogen depending on the chance for rain. It is not wrong to wait to apply nitrogen until you anticipate rain coming.

For more information on stockpiling, get a copy of Extension publication FMI: AGR-162 Stockpiling for Fall and Winter Pasture from your county Extension office.

“The critical issue is the timing of the nitrogen application. August does seem early to be talking about fall and winter pasture,” Henning said. “However, research shows that delaying fertilization to even September 1 can cut the yield produced by 80 percent, depending on the weather. Early application of nitrogen will produce more pounds of forage per pound of nitrogen applied, making the fertilizer dollar go farther.”

Understanding summer annuals can help maximize their value and minimize their problems. And looking ahead to stockpiling some fescue for fall and winter grazing will help extend your grazing season and keep costs low.

Contact: 

Jimmy Henning 859-257-3144