Alfalfa; Winterkill – What causes it?

At current one of the most profitable crops in agriculture market is Alfalfa. A high demand, long-term perennial that can be marketed to producers of virtually any species of livestock.  In my more frequent travels to Kentucky, Illinois, Indiana, and Ohio winterkill is the topic that moves to the top of the list when looking at the liabilities of this royal crop. Hands down, a perineal crop that produces at higher levels for five or more years is a crop that can be a wise investment.  According to many experts, most fields live from 4 – 8 years, however, fields are known to have lived for 20 or more years. Obviously, a crop that can cost from $200.00 to $400.00 per acre to establish is a huge investment.  It’s also obvious that if I can get 8 years of production versus 4 years and maximized production every year my ROI is significantly higher.  Is it possible for me to stretch that crop out and enjoy the gains and sheer beauty of that thick robust stand for another 4 years? Many producers that I have spoken with really can’t see that far with the possibilities.  Their argument is that they have never seen a stand that stayed that healthy, and when fed only with the mentality of replacing the nutrients lost, it is no wonder.

Based on my research, 8, 12 even 15 years of longevity can and should be in the farm plan when producers look at soil health prior to preparing the seedbed. If that premier stand will last for 12 or more years, why would I plant a cheaper, less productive variety?  It does, however, all go back to soil health, which is not something that you do 30 or even 60 days prior to planting.  At CaluSolv we recommend that the producer start a full year prior to planting by pulling the right combination of a soil test.  Calcium is king, not only with crop production but also in the preparation of soil for feeding the soil microbiome.  This is not just a lime situation, as lime is calcium carbonate and often misunderstood in its effectual role. We do get calcium when lime is applied, however, it is the carbonate side that deals with pH changes.  A great example of this is that I can take beach sand that has a pH of 7 and calcium levels are minimal at best (often 300 lbs or less per acre).  That being said, the producer can apply lime at a rate of several tons per acre and move the pH up substantially and yet the soluble calcium levels remain significantly less than what is needed to maximize the crop, both in production and quality.

I digress.  Back to our original topic of winterkill and what causes it.  In wintertime soil conditions when calcium levels are deficient for healthy microbiome conditions, compaction is a dangerous liability as it leaves no room for air in the soil.  This leads to situations where the soil heaves and creates shearing forces on crops and very destructive on alfalfa taproots.  I am including several photos from hay and forage magazine and the University of Wisconsin that clearly show either broken or what I call deeply bruised tissue that is dying because of the heaving that occurred. The Wisconsin field is a low area of the field and often that too contributes to the problem as that area will be more compacted because of water issues.

Winterkill area in a low area of a Wisconsin field

Bruised tap root tissue that will ultimately kill the plant

Mowing in Kentucky