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Alfalfa is a perennial forage crop. Alfalfa leaves use sunlight to produce sugars and starches.
The fall of 2015 will be remembered for some different weather patterns. First will be the unusually warm and sunny conditions that lead to excellent growth of fall seeded oat crops and regrowth of alfalfa. Then the heavy rains immediately after Thanksgiving and the sudden drop in temperatures from the 50's to the low teens. The question has already been raised on what affect these sudden change in conditions will have on alfalfa winter survival.
Survival and high production of an alfalfa stand begins with an understanding of root reserves. Alfalfa is a perennial forage crop. Alfalfa leaves use sunlight to produce sugars and starches. These carbohydrates are used by the plant to support new growth. When levels of carbohydrates exceed the need for regrowth the excess amounts are transported to the tap root and stored for future regrowth. This regrowth may come during the growing season following mowing or in the spring. During winter alfalfa plants may be in "hibernation" but they still carry on basic plant functions at a slower level. These stored carbohydrates are necessary for winter survival as well as regrowth. Management that maximizes root reserve levels at the onset of cooler temperatures and shorter days in the fall sets the stage for optimizing alfalfa stand survival in the spring.
Winter survivability is influenced by many factors:
Stem counts are used to evaluate yield potentials of alfalfa stands. Make a frame of wire one foot square. Toss the frame into a stand and then count the number of stems within this square foot area. Stands with greater than 55 stems/ft² will have highest yield potential. Stands with 40 to 55 stems/ft² will have a yield loss and stands with less than 40 stems/ft² should be considered for rotation.
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