Dry conditions and drought during much of 2012 and over-grazing late into the fall have damaged many Iowa pastures. "Pastures with bare areas and thin sod cover will be less productive and more susceptible to weed encroachment," points out Steve Barnhart, Iowa State University Extension forage agronomist. "Most producers want to maintain their existing pastures, but might like to improve them by doing some form of partial reseeding. Frost-seeding is one method that should be considered."

Now, in late February or the first half of March, is the time to frost-seed pastures and Barnhart offers the following recommendations. If you have questions, he can be contacted at [email protected].

FROST-SEEDING CAN HELP: Many pastures were stressed by extreme drought last summer and over-grazing into late fall. Pastures with bare areas and thin sod cover will be less productive and more open to weed growth in 2013. Consider improving these pastures by doing some type of partial reseeding. "Frost-seeding in late winter is one method that should be considered," says ISU Extension forage agronomist Steve Barnhart.

Being timely is first step when frost-seeding existing pasture in late winter

Frost-seeding is the broadcasting of forage seed on existing pasture in late winter, with the goal of freeze-thaw cycles shallowly covering the seed. Early spring rains also help with seed coverage on bare areas. Operating broadcast machinery on frozen or dry pasture surfaces is safer than operating on snow or when soil surface conditions are wet and slippery.

Red clover has been the most consistently successful forage species to establish using frost-seeding. Other legumes, such as white clover, birdsfoot trefoil and alfalfa can be frost seeded, but often with slightly less success. Frost-seeding more grass seed or seed of more productive grasses are also often not very successful.

In Iowa, the experience of farmers who've used this practice has been best when legume seed is broadcast on the thinnest, least vigorous pasture areas. Success has also been improved where the previous grass stand has been heavily grazed, thus, exposing more areas of bare soil. Successful frost-seeding also requires adequate soil moisture, and average or better rainfall and growing conditions. Frost seeding efforts in years with dry spring weather have often not been as successful.

Should you broadcast seed on a pasture or use a drill to interseed it?

While frost-seeding is the easiest and likely the least expensive pasture seeding approach, using a drill (this is called interseeding) for more precise seed placement and seeding when soil conditions are more supportive of quick germination usually provides better and more uniform stand densities.

Other suggestions and information about soil fertility and grazing management as part of the frost-seeding effort are provided in an ISU Extension publication on frost-seeding. You can find this publication online at th ISU Extension website. Or, you can ask for a copy of this ISU frost-seeding bulletin, Improving Pasture By Frost Seeding, PM 856 Revised, and other pasture management publications, at your county ISU Extension office.