The Fall Cutting Decision -Again Mike
Rankin
It's that time of year again. Do
I cut alfalfa or not? The
big picture answer is that such a practice comes with some degree of risk. For the past several years, however, fall cutting has not
been extremely detrimental to alfalfa stands.
So what might be different about this year? Let's examine the issues.
It's 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 (as it appeared that many did!).
It also offers producers the opportunity to harvest relatively high
quality forage. From a
winterhardiness and persistence standpoint, alfalfa varieties today are
better than they were ten years ago. Some
really poor survival years in the early 1990's helped refocus breeding
efforts in this area.
Harvesting alfalfa in October can, and often does, 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 and
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 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 has 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. If I don't
harvest, won't the stand smother itself out?
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. 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.
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