March is frost seeding month in Michigan

Frost seeding pastures with improved legume and grass varieties is a very economical way of improving pasture yield and quality.

March is the month across much of Michigan to improve pastures by frost seeding legumes like clovers or some grasses into them. Frost seedings are most successful when the seed is broadcast approximately 45 days before grass growth begins in your area.

Frost seeding is the practice of broadcasting seeds of improved varieties of red clovers, white clovers, birdsfoot trefoils, or some grasses in late winter across pasture lands. The freezing and thawing action of the soil surface over the following weeks helps to incorporate the seed into the top soil layer providing good soil-to-seed contact and stimulating early germination. It is one of the most economical, environmentally friendly ways to improve pastures.

Research conducted at the MSU BioAgResearch Station in Lake City, Michigan, over a ten-year trial experiencing a wide range of weather conditions revealed that frost seeding on predominately orchard grass pastures every third year yielded as much forage as applying 163 lbs. of actual nitrogen fertilizer per acre annually (354 lbs./acre of 46-0-0). It yielded an extra 2.08 ton/acre of forage on average over the control plot where no seed nor fertilizer was applied. When the cost of the seed and the broadcasting are factored in, and it is assumed a frost seeding of clover will last three years, the cost of this extra forage produced is calculated to be less than $7 per ton. Compare that to the cost of applying 100 lbs./acre of actual nitrogen fertilizer at a current fertilizer price of $600/ton for 46-0-0, and the extra forage yield would cost over $45/ton just for the nitrogen fertilizer and the spreading cost. Frost seeding is so much more economical than applying nitrogen fertilizer that even if one year’s frost seeding fails because of weather conditions, you can afford to do it again next year and it will still be cheaper than applying nitrogen every year.

But frost seeding is not foolproof. It must be done properly to have a high degree of success. Below are guidelines to make frost seeding successful:

  • Frost seeding works best on loam or clay based soils – sandy soils will not work well for frost seedings as on sands there is not enough soil movement and it is better to use a no-till or conventional grain drill to apply the seed into the pasture sod in April.
  • Graze the pasture tight in late fall to weaken the grasses present so they will not be as aggressive next spring, and to expose more soil to provide better soil to seed contact next spring.
  • Soil test the pasture to make sure fertility is adequate, paying special attention to phosphorus as young seedlings need phosphorus for good seedling root growth.
  • Shoot for a 60% grass, 40% legume mix in the final pasture stand as this balance will provide optimum pasture growth and forage quality without raising the risk of animal bloat too high.
  • To attain these mix percentages, frost seed 8 lbs./acre of red clover, or 1-2 lbs./acre of white clover, but realize it is best not to apply both red and white clover in the same year because of the competition they give each other, and because combined they raise the risk of bloat.
  • If the legume choice is birdsfoot trefoil, seed 10-12 lbs./acre as bloat is not an issue with trefoil and it does not establish as easily as the clovers.
  • Use improved varieties of these seeds (the best variety the seed company has) as these varieties seem to be more aggressive and catch better than cheaper bin run varieties and they usually last longer in the stand.
  • Frost seeding is better done on a little snow cover as it is easier to see the spread pattern on top of the snow – usually mid to late March is good for much of Michigan.
  • Let the pasture grow up to 8-10 inches tall and graze it down tight. Let it grow up to this level again and graze it tight again. Clover tolerates shade from the competing grass for a while but if the grass gets too thick and tall, which most grass stands do in the spring, the young clover seedlings need some chance to receive sunlight to catch up.
  • Continuous grazing is not good for new clover seedlings. After grazing the seedlings need a chance to grow, so rotating the animals to another pasture is advised.
  • Do not fertilize the frost seeded pasture with nitrogen fertilizer the first spring of seeding as it will create too much grass competition for the clover seedlings. Usually by mid-summer the clovers are visible and can handle the grass competition, so small amounts of nitrogen could be applied, if needed, at that time.
  • Red clovers will last 2-3 years normally in a stand. White clovers will persist 2-4 years. Evaluate pastures in late summer to early fall, if rainfall is adequate, to determine if a frost seeding of legumes will be needed next spring.
  • Grasses that can be frosted seeded include annual and perennial ryegrass, festulolium and some others.
  • If weeds are a problem in a pasture, think about soil testing, applying necessary lime or fertilizers, and spraying a labeled herbicide for weeds, if necessary, a year before frost seeding. Most herbicides that control pasture weeds will also kill clovers that you frost seeded.
  • Frost seeding pastures with improved legume and grass varieties is a very economical way of improving pasture yield and quality. When done properly and followed by adequate summer rains they can be successful.

For more information, contact MSU Extension grazing educator Jerry Lindquist toll-free at 888-678-3464, ext. 6723, or at .(JavaScript must be enabled to view this email address).

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