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Assess Your Stands to Verify Yield

Assess Your Stands to Verify Yield

It’s a best practice to assess alfalfa stands during spring green-up, regardless of winter conditions. Stand assessment can help verify yield potential, and re-affirm decisions to either keep or terminate your field(s) of alfalfa.

Winter periods of little or no snow cover, coupled with big temperature swings in late winter and early spring, were followed by more weather below freezing.  These weather patterns have many alfalfa growers scratching their heads about how well their alfalfa stands might fare through these temperature swings.

Snow cover is a good insulator during winter cold, but lack of snow cover can be hard on over-wintering alfalfa, particularly when soil temperatures at the crown level (2 inch soil depth or so) drop into the low teens Fahrenheit.  This can occur when a lack of snow cover is coupled with sub-zero air temperatures for several days during winter.  Alfalfa crowns that appear dis-colored, with a pithy appearance are not likely to recover.  During spring greenup, affected crowns will not generate buds that would normally develop into elongating stems.  Stem counts during spring greenup will tell the story on likely stand productivity.  A stand that averages 55 stem per square foot has been shown to maintain full yield potential, while stands with less than that amount may drop in yield.  Stands with substantially fewer stems can be expected to drop further in yield potential and should be considered for rotation to take advantage of nitrogen credits.

Another condition to be aware of is frost heaving.  When frozen soils thaw, then re-freeze during a cold snap under saturated moisture conditions, ice lens formation within the soil can temporarily lift the soil surface and lift alfalfa crowns along with it, even breaking off taproots.

Stands of alfalfa with significant heaving injury usually need to be replaced.  Plants that heave enough to expose the crowns above the soil surface risk having crowns severed by harvest equipment. There will be no subsequent growth after first cutting when this occurs on a widespread basis within a field.  If tap roots are severed underground, there may be some continuing growth but it will not thrive.  Fields with substantial winter heaving or frost heaving damage should be considered for termination in time to plant a different crop.  If forage is needed, such fields  can often muster a first crop but once crowns are cut off by harvest equipment, regrowth should not be expected.

For more information on this subject of stand assessment, including photos of healthy versus affected plants, please visit

Alfalfa Stand Assessment: Is this stand good enough to keep? – Team Forage (wisc.edu)

Written by Robin Newell