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Published March 30, 2008, 12:00 AM

Ag Matters column: Include grasses with your alfalfa seeding

Including grasses in your new alfalfa seeding is worth considering. Years ago, mixing grasses with alfalfa was standard practice, whether seeding an oat companion crop and/or including timothy or smooth bromegrass with the under-sown alfalfa. This practice lost favor for a time, but recent developments in forage testing and some frustrations with alfalfa winter injury have helped restore the respect that grasses, somewhat unfairly, lost.

By: by Jim Stordahl, Clearwater/Polk Extension?, DL-Online

Including grasses in your new alfalfa seeding is worth considering. Years ago, mixing grasses with alfalfa was standard practice, whether seeding an oat companion crop and/or including timothy or smooth bromegrass with the under-sown alfalfa. This practice lost favor for a time, but recent developments in forage testing and some frustrations with alfalfa winter injury have helped restore the respect that grasses, somewhat unfairly, lost.

There are many reasons to include grasses with alfalfa. Your reasons may vary from your neighbors, but adding grasses offers many advantages.

Harvested yield is the single largest driver of profitability when producing stored forage, and alfalfa-grass mixtures often yield more than alfalfa alone. The fixed costs of forage harvesting are large so every cutting needs to produce a bountiful harvest.

A small grain or Italian/annual ryegrass companion crop with a spring seeding provides greater seeding-year yield than direct-seeded alfalfa.

Sod-forming grasses like low-alkaloid reed canary grass or smooth brome grass enable traffic on the field when more soil moisture is present and will accelerate drying rate, reducing the potential for weather-related yield and quality losses.

Orchard grass and tall fescue have good fall growth that enables a productive fall harvest/grazing while providing more residue than just alfalfa stubble to catch snow and insulate alfalfa crowns.

Grasses, especially those with stems, present accelerated swath drying rates. Grasses that produce stems with every growth cycle such as reed canary grass, smooth brome grass and timothy create more fluffy swaths that dry faster. This may not be true with all grasses though. Some leafy grasses with shiny surfaces, such as tall fescue and the rye grasses, will not speed drying rates significantly.

Fall growth and residue of grasses provides better snow catch and insulation than alfalfa stubble alone, so alfalfa crowns are better protected from winter injury. Also, if winter hardy grasses are used, they provide insurance if the alfalfa does have winter kill.

At similar stages of maturity, grasses have higher fiber, especially NDF, than legumes, but this fiber is considerably higher in digestibility. The relative feed value (RFV) index is a good index for alfalfa quality, but was never intended for use with grasses as it tends to undervalue the feeding value of grasses. The new relative forage quality (RFQ) index provides a better reflection of grass’s higher fiber digestibility and the impact of that on energy and intake potential.

Weeds are opportunists that encroach in perennial forage stands when too much bare soil is exposed for too long. Some grasses improve the speed with which full soil cover is achieved during the seeding year. Many grasses also provide more long-term cover, particularly if broadcast seeded or if they are sod-formers. This reduces opportunities for weeds to establish.

Bloat does not tend to be an issue with haylage or hay; grass-alfalfa mixtures have less bloat potential than pure alfalfa when grazed.

Prairies are diverse mixtures of grasses and legumes, not legume monocultures. While our forage production methods are certainly more intensive than the native prairie-bison system that used to dominate much of western and southern Minnesota, surely there is some sound ecological basis to the complex design of natural forage stands of grasses mixed with legumes.

Finally, it’s critical to select a grass variety that will compliment your legume. Many grass varieties do not match the maturity of the legume, and producers find the grass to be too mature by the time the legume is at the ideal forage quality stage. So if you add a grass species, it pays to ensure that your varieties “match up” with each other in maturity. We have detailed information that will help you select proper grass species and the proper variety.

If you have Internet access and would like to do your digging, the University of Wisconsin Web site (www.uwex.edu) has excellent information on all forages, but especially on grasses.

For more information on selecting grasses for your legume, contact me at the Polk County office in McIntosh or at the Clearwater County office on Wednesdays. Our toll free number is 800-450-2465. If e-mail is your thing, contact me at stordahl@umn.edu. Source: Paul Peterson, University of Minnesota Extension forage agronomist.

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