It's cheap, it's easy and with a 70 percent success rate, you should frost seed pastures every year.Frost seeding is the practice of spreading seeds on frozen ground and then letting nature run its course.
To add white clover to pastures, Dan Undersander, UW-Extension forage agronomist, advised broadcasting the seed at about 2 pounds per acre. Broadcasting may be done with a hand spreader or even incorporated into a fertilizer application.
"We recommend that you seed in the spring, usually March, when the snow is off the ground and you still have freezing nights and thawing during the day," Undersander said. "It's best if the pasture is grazed or clipped down short so the seed goes all the way to the ground."
March 15 is typically the optimal time for frost seeding in much of Wisconsin and northern Illinois depending on the season. The farther north you are, the later the potential optimal date for seeding, he said. Frost seeding isn't limited to adding legumes to a pasture, added Jeff Miller, seed salesman with The DeLong Co. in Clinton. People also seed such grasses as perennial and annual rye and varieties of fescue and orchard grass.
"The biggest thing is getting the seed to the right spots on the soil," Miller said. "We can't always guarantee perfect results, but we can give ourselves the best chance of success."
As the soil freezes overnight and then thaws during the day, the seed is drawn into the ground, he explained. Broadcasting the seed in March and having it work into the soil during the early spring helps the seed take advantage of subsequent rain or snowfall.
Fertility also is an issue. Miller and Undersander both promoted having a soil test done and applying fertilizer accordingly. Miller added that a soil test every three years is generally enough as long as you have a good idea how much fertilizer is needed.
"You can often spread seed and fertilizer in the same operation," Miller said. A couple hundred pounds of nitrogen per acre can potentially double forage yield.
Weather is a big factor in frost seeding. Spreading seed on frozen ground and then getting heavy rains, for example, can affect your outcome.
"In that case, the bottoms of the hills are going to be pretty lush and the hillsides not so much," Miller said. Likewise, extended dry and hot weather can reduce success.
As for seeding cost, Miller said it depends on what type of seed you use, how much and if you include fertilizer and soil testing.
"If your pasture is already in pretty good shape and you're just trying to keep it that way, you're probably looking at $10 an acre and maybe less," Miller said.
If you're tackling a run-down pasture, more seed and fertilizer costs are likely. Miller said pasture restoration costs can run up to $25 or $30 an acre. Basic pasture seed mixes vary in cost from $1 to up to $2 a pound. Heavy seeding rates are around 10 pounds per acre.
Because frost seeding is fairly inexpensive and easy to do, Undersander and Miller both said the practice is worth doing every season. There's enough variability that if frost seeding doesn't work one year it probably will in following seasons.