Seed legumes on snowy frozen field, says MU Extension forage specialist

COLUMBIA, Mo. – Winter seeding clover over grass pastures works best in February. Frozen fields are ideal and a snow cover makes seeding easier.

Adding a legume to fescue or other cool-season grass makes money, says Rob Kallenbach, University of Missouri Extension forage specialist. “Investing in clover seed is more profitable than investing in Wall Street,” he said.

There are at least four reasons for overseeding legumes into grass pastures, Kallenbach says. It is so easy. But the main reason is legumes add pounds of gain on beef calves.

“We’ve recommended adding clover for years,” Kallenbach says. “But now, with the price of calves, it means more money.”

Four years ago, calves sold for a dollar a pound. Now they can double that.

MU grazing studies show an extra quarter pound of gain a day from calves on clover-mix pastures.

“If that doesn’t sound like much, multiply that out by 200 days from birth to weaning. That’s an extra 50 pounds per calf,” Kallenbach says. “Do the math for your herd for all your calves.”

Clover makes a big difference in diluting toxins from endophyte-infected tall fescue. Endophyte, a fungus in the fescue, cuts calf daily gains and reduces milk from mama cows.

Results are even better on nontoxic fescues.

For all those benefits, the investment in seed and labor is modest, Kallenbach says.

The legume seed is broadcast over pastures. With freezing and thawing of the soil, no tillage is needed. Expanding and shrinking works the tiny seed into the ground, but not deeply.

“Frozen ground makes easy driving across pastures. A snow cover shows tracks of where you’ve seeded,” Kallenbach says. Seeding should be done by March 1 to give legumes an early start.

It’s best to have the pasture grazed down short. “I would never say overgraze,” Kallenbach says. “But if overgrazing happened, that can help the legume seeds.” Seed should hit the ground, instead of landing on thatch.

Red clover seed, the most widely used legume, doesn’t cost much.

Lespedeza and birdsfoot trefoil, longer-lasting legumes, will cost more.

White clover is often overlooked for what it adds to a grazing mix. “Often it looks like it dies in a dry spell,” Kallenbach says. “But the first fall rain brings it right back. It responds to moisture.”

If managed for seed set, lespedeza, once started, can last forever, he says. “However, red clover should be seeded every year. It’s a perennial, but disease wipes it out after two years.” Clover seeding rates are only 3 to 4 pounds per acre.

Since legumes make their own nitrogen, no nitrogen fertilizer is needed. Legumes even share nitrogen with adjacent grass. That cuts fertilizer costs.

Kallenbach assumes producers keep soil fertility, especially potash and phosphorus, up to soil-test recommendations. Most important, legumes don’t tolerate acid soils very well. That means lime should have been applied to raise soil pH.

If soil fertility and pH are not high, lespedeza best tolerates poor soil. Lespedeza takes 8 to 10 pounds of seed per acre. Trefoil takes 5 pounds.

All legumes need the appropriate rhizobium, the nitrogen-fixing bacteria, to take nitrogen from the air. Inoculants added to the seed assure nitrogen fixation.

The only hitch might be in getting the right inoculant for the legume to be sown, Kallenbach warns. “Inoculants aren’t always on the shelf when needed. Tell your dealer early what you will need.”

Most alfalfas, and some clover, come pre-inoculated. Lespedeza and trefoil are not often pre-inoculated. Each legume needs a different rhizobium.

Farmers often talk of good clover years. Those years depend on rain at the right time. And often they come a year after a drought. The cool-season grass will be grazed down short after a dry year. That gives legumes an edge in starting the next spring.

Freezing weather at planting isn’t a problem. However, a late-spring freeze sets back tender young clover, Kallenbach says.

Grazing studies are conducted at research centers of the MU College of Agriculture, Food and Natural Resources.