Importance of First Year Alfalfa Yields

Some significant changes are occurring in the way Wisconsin farmers manage alfalfa. One is that less alfalfa is being grown with a cover crop than previous. In 1990 and previous over 90% of the alfalfa was seeded with oats as a cover crop; this figure has declined to less than 50% alfalfa seeded with a cover crop. With direct seeded alfalfa, first year yields become economically important.

The oat acreage graph from Wisconsin Agricultural Statistics shows that over 700,000 acres of oats were grown in 1990, most of this oats had alfalfa underneath it. In 2000, less than 300,000 acres of oats were grown. Oat acreage has declined as the need for straw has decreased. Statistics also indicate that, in recent years, approximately 100,000 acres of oats are harvested for haylage when no significant alfalfa winterkill has occurred. Oatlage has never been popular due to its low palatability and difficulty to make with good quality.

When alfalfa is seeded without a cover crop (or with oats sprayed at 6 inches with

Poast Plus), seeding year management becomes significant to get the most yield. First, it is important to select the right variety. Some alfalfa varieties establish significantly faster than others and yield more in the seeding year. We have begun publishing seeding year alfalfa yields in the UW Extension publication, Perennial Forage Variety Update. Our recommendation is to pick high yielding varieties over multiple sites and years (as in the past) and then to select those varieties that also yielded well in the seeding year, if the field is to be direct seeded. The data in the graph at left show that the average range in yield (darkened area at the top of each column) from most studies over the past 5 years has been about half a ton. This means that by selecting high yielding seeding year varieties farmers could be getting an extra half a ton of forage compared to the low yielding varieties in the seeding year.

Dan Undersander

January, 2001