"I Gotta Lot of Alfalfa
  Out There"

Note: This is a 1996 refried article with a 1997 twist (I bet you can't wait 'till 1998).

It's October 16, the end of the "critical fall period" for alfalfa and this year, the end of the growing season as a frost occurred last night. The first call came into the office this morning wanting some advice on cutting alfalfa this fall. The weather has been good and there's plenty of regrowth.

Farming is, always has been, and always will be a game of odds. Because weather is so unpredictable, so are most outcomes when it comes to growing and maintaining crops. This fact is always brought to light each spring as we hope to witness the alfalfa greening ritual.

Every year we get calls to the UW Extension office from forage producers who want to know if it is okay to cut their alfalfa in October. I'm sure most would like the simple "yes" answer but instead most get an agronomic dissertation, a portion of which is presented here.

Although I often shy away from making any predictions on alfalfa winter survival, this year may not be a good one to take the risk of a fall cutting. I say this for two reasons. First, I'm a big believer in the "multiple stress" theory and this year there were many alfalfa stands severely stressed by potato leafhopper pressure. Couple this with any disease pressure and a fall cutting may be the "last nail in the coffin". The second reason why this may not be a good year to take the fall cutting risk is that this fall has been characterized by above normal fall temperatures not especially condusive for winter hardening alfalfa plants.

It is unlikely that October-harvested alfalfa stands will regrow to the point of significantly reducing stored root carbohydrate reserves. This makes such a practice somewhat less risky than harvesting during September. It also offers producers the opportunity to harvest some relatively high quality forage. However, research and farmer experience confirm that a late fall harvest is not without risk.

Harvesting alfalfa in October can and generally will result in yield reductions next spring, shortened stand life, and a higher incidence of root disease. The degree to which all of these occur depends largely on the type of weather we experience during late fall, winter, and early spring. For example, an alfalfa plant will "harden" better during a fall typified by clear, cool weather than one characterized by cloudy, warm conditions. Obviously, snow cover during the winter and early spring will be of great benefit as well. A recent Michigan State University study found that the number of temperature fluctuations above and below 32 degrees F was also an important factor in determining alfalfa winter survival.

My observations have always been that the simple presence of dead alfalfa stems from the fall before usually have a large impact on alfalfa survival. Certainly they help to catch snow and inhibit the snow from melting away. However, there seems to be other advantages. Possibly, they retard temperature fluctuations at the soil surface. This may be especially important in the early spring.

Many producers are concerned with large amounts of alfalfa forage smothering itself out during winter. I have never seen this to be a problem unless there is a significant amount of grass in the stand. After alfalfa plants freeze, the leaves drop off and the remaining stems pose little threat to smother remaining plants. I have advised producers to cut new seedings in the late fall where a massive flush of annual foxtail is dominating the stand. This is a situation where alfalfa will smother under the grass.

Another concern offered by forage producers for not leaving large amounts of standing forage in fields over winter is the impact it will have on first-cut forage quality next spring. A Fond du Lac County Forage Council demonstration project addressed this issue several years ago and found that the dead plant residue can lower overall forage quality . However, the effect varied from year to year and was generally small when compared to the risk involved for fall cutting based on forage quality reasons alone (see Alfalfa Fall Aftermath Growth - impact on forage quality).

The bottom line is that there is no right or wrong answer for making late fall harvest decisions. The economic feasibility of harvesting in October depends largely on uncontrollable factors and the individual need for additional forage. There certainly is no need to risk a potentially productive stand if the forage is not needed.

If stands are cut this October, leave several strips of uncut forage to monitor growth and survival differences next spring. If nothing else, it makes for good photo opportunities for the county agent.