April 9, 2019 - 8:32am -- ferencak.2

For anyone with an alfalfa field out there, if you have not already walked over the field, then I encourage you to get out and walk your fields.  I have seen some alfalfa fields pretty well decimated by heaving injury.  I’m talking about 50 to 75% of the field or maybe more, with alfalfa plant crowns heaved two to five inches out of the soil.  Where plant crowns are heaved more than a couple of inches out of the soil it is a good bet that the taproot is broken and those plants are dead.

The typical advice is evaluate alfalfa stand health after there is two to four inches of growth to be able to count stem numbers per square foot.  However, that evaluation assumes that heaving damage is minimal.  In those circumstances, an alfalfa stand needs at least 40 stems per square foot to be economically viable and 55 or more stems per square foot to insure 100% yield potential.  Growers encountering severely heaved stands already know that some type of replant option is necessary.  Overseeding alfalfa back into an existing alfalfa stand or into a recently terminated stand is not an option.  Autotoxicity causes extensive death of new alfalfa seedlings. For this reason, the standard recommendation is to rotate out of alfalfa into a different species for at least one year before returning to alfalfa. 

Options to consider depend upon the extent of heaving damage, type of forage needed, the timing of forage harvest and the forage harvest system that is used.  If severe heaving damage is confined to patches within the field, for example the low areas, consider renovation of the stand.  In this case, the areas of the field with productive alfalfa plants can remain and the patches can be re-seeded. 

If the goal is to keep the field for more than one year, one option is to plant red clover or a red clover/grass mixture.  Most red clover varieties will last for two production years, but there are several improved varieties that can maintain production for three years consistently and possibly four in some situations.  If the goal is to get one more year of production and some type of legume is desired, consider berseem clover, crimson clover or even field or forage peas.  All of these are going to act like an annual crop.  Make sure to look at the cost of seed and weight that against potential yields.  Anytime another grass or legume is being patched into an existing stand, recognize the newly seeded area will need some time to get established before it can be harvested, likely a minimum of sixty days after planting.

If the entire field needs to be rotated to another crop, corn silage has advantages over other forage options in terms of yield and nutritive value, especially energy.  As a grass plant, corn is able to take advantage of the nitrogen credit provided by the previous alfalfa stand.  The disadvantage of corn silage is that forage harvest is delayed to the end of the growing season.  Corn silage is a fermented crop and must be well managed in terms of timely harvest, storage and feed out to take full advantage of its yield and nutritive content and to make it an economical forage.  Another warm season annual grass option is to plant a BMR sorghum x sudangrass hybrid or a BMR sudangrass variety.  Plant when soil temperature is around 65 degrees F. This will allow a forage harvest 45-55 days after planting and provide subsequent harvests approximately every 30 days into September under good growing conditions.  These forages are best harvested either as a wrapped baleage product or as a chopped and ensiled forage.

Some other early spring seeded cool season grass options that will produce an earlier forage harvest include the spring cereal grains such as oats, barley, and triticale.  Italian ryegrass is another spring seeded grass option that can produce a first harvest in approximately sixty days after planting and then subsequent harvests every 25-30 days.  Mark Sulc, OSU Extension Forage Specialist and Bill Weiss, Extension Dairy Specialist recently wrote a very good article entitled “Early Spring Planted Forages for Dairy Farms” in the Buckeye Dairy News newsletter.  The article contains details on planting dates, seeding rates, nutritive values, and expected yields.  The article is available on-line at https://dairy.osu.edu/newsletter/buckeye-dairy-news/volume-21-issue-2 or contact the Wayne County Extension office at 330-264-8722.  I can provide you with a hard copy of the article.

 

Rory Lewandowski is an OSU Extension Agriculture & Natural Resources Educator and may be reached at 330-264-8722.

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