Forstseeding Pastures in Spring

Dry conditions during much of 2012 and overgrazing 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. Most producers want to maintain their existing pastures, but might like to improve them by doing some form of partial reseeding. Frostseeding is one method that should be considered.

Frostseeding 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 helps 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.  There is some ’folk lore’ that frost seeding works best when seed is broadcast on snow. I am not aware of any research that substantiates this.

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

Iowa producer experience 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 frostseeding 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.   While frostseeding is the easiest and likely the least expensive pasture seeding approach, using a drill (interseeding) for more precise seed placement and seeding when soil conditions are more supportive of quick germination usually provide better and more uniform stand densities.

Other suggestions about fertility and grazing management as part of the frostseeding effort are provided in an Iowa State University Extension publication on frostseeding.  You can find this publication at:  http://www.extension.iastate.edu/Publications/PM856.pdf. Or, you can ask for a copy of the Frostseeding bulletin and other pasture management publications at your local Iowa Extension Office.

 Provided by:   Steve Barnhart, ISU Extension Forage Agronomist,  email    sbarnhar@iastate.edu