Consider Variety Choices for Top Yields

Seed selection for alfalfa means more looking at the latest genetics.

Published on: Feb 12, 2010

When the seed salesperson makes a visit the discussion usually starts with corn and the associated volumes of current university, company, and on-farm performance trial data to pore over. Next are soybeans with a similar arsenal of comparative yield numbers. Finally, it's time for the alfalfa decision.

Selecting top alfalfa varieties is not an easy chore. Unlike corn and soybeans, alfalfa does not lend itself to easy on-farm testing and any final analysis takes a few years to document. Several Midwest universities test alfalfa varieties and that's a good place to start for performance data. For a single year, it's not unusual to see differences of nearly two tons of dry matter yield per acre between the top and bottom commercially available varieties. The economic consequence of selecting one of the poor performers is mind-boggling.

Producers often make hasty alfalfa variety selection decisions for several reasons. In addition to the relative lack of performance data, alfalfa yield differences are difficult to see in the field. A one-half ton (dry matter) yield advantage is hard to notice or measure in a single year because it's spread over multiple cuttings. Yet the value of a half ton of alfalfa is similar to 20 bushels of corn. Here are some guiding principles for selecting alfalfa varieties:

Don’t bet on a horse named Vernal

If horses race like alfalfa varieties place, don’t put your money on Vernal or similar older varieties. Most growers know this but it never hurts to reinforce the principle just in case the neighbor starts bragging about the great deal he got on cheap seed. Vernal, and similar varieties, simply lack the yield potential and disease resistance to compete with modern genetics.

Don’t marry a girl after only one date

Most people would agree that this is pretty good advice when it comes to picking a mate. It’s also good advice when selecting alfalfa varieties. Single location, single year data is not enough information to confidently pick a “winner.” Performance changes with environment. Seeking-out those varieties that perform in the top 25 percent of tested varieties at multiple locations (even other Midwest states) is the best indicator of year after year performance on your farm. The need for feed remains consistent on most farms. Consequently, there is a need for consistent, high performance from the alfalfa varieties you plant.

Don’t marry a girl ONLY because she has blonde hair

Once again, good advice for long-lasting marriage bliss. It's also good advice when selecting alfalfa varieties. There are many varieties in the bottom half of performance trials that have very admirable single-trait qualities. Selecting a variety based solely on a single trait is always dangerous. This holds true for any trait – disease resistance, forage quality, insect resistance, herbicide resistance, etc. It’s important to look at the entire package and at relative yield performance in the field over several years.

Money isn't everything

There's a wide variation in the cost of alfalfa seed. It's the last selection variable that should be considered and only after a "short list" of high, consistent performers is developed. We've already addressed the pitfalls of purchasing "cheap" seed. Likewise, high-priced seed may not always guarantee high performance. The real "cost" of seed is not reflected in the purchase price alone. Seeding an inferior yielding variety, regardless of price, means that long-term costs of production are higher per ton of forage produced. Relatively large differences in initial seed price are quickly made up with relatively small advantages in yield and persistence.

We will likely not see the same sustained increase in yield improvement for alfalfa that has been accomplished in annual crops like corn. However, there is no question that recently developed alfalfa varieties are far superior to what was on the market 15 years ago. Some new varieties exhibit the entire package of high disease resistance, fast regrowth, strong persistence, and exceptional yield. However, like picking your spouse, identifying the right alfalfa variety takes some time investment.

--Rankin is a crops and soils agent with the University of Wisconsin Extension.