Managing alfalfa for highest yields
With the end of summer in sight, alfalfa growers have two primary things to think about when evaluating their forage needs and alfalfa stands in the fall:
• How healthy is the stand? This, in part, determines the likelihood of it surviving the winter.
• Do I need to take another cutting after Sept. 1 to have enough forage for my operation?
Overall health of the stand can be determined by the number of plants per square foot. Select five random, yet representative, locations for each field and count the number of healthy growing plants. Then average your findings for each field. The table (below) indicates the overall productiveness of that stand and its rating for winter survivability.
Many factors impact the overall health of the alfalfa stand, affecting its ability to survive the winter. Some factors aren’t controllable:
• lack of extended periods of cool temperatures and/or extended wet conditions in the fall, which prohibit “hardening” of the plant
• lack of snow cover to insulate plants in the winter (Soil temperatures below 15 degrees F can injure or kill plants.)
• midwinter thaws that cause plants to break dormancy
• ice sheets that can smother plants
The controllable factors that promote the survivability of the stand are:
• selecting varieties that have good to excellent winterhardiness and good to excellent disease-resistance ratings
• making sure soil fertility, especially potassium, is sufficient
• keeping soil pH at 6.6 to 7.2
• not taking a cutting from Sept. 1 through Oct. 15 from any stand you plan to keep in production the following year
If you need another cutting after Sept. 1 to have enough forage for your operation, consider the following. For Minnesota farmers, the final cut should come after Oct. 15. Taking it earlier could allow too much regrowth, robbing roots of storage carbohydrates required to survive the winter. The final cut should leave about 6 inches of stubble for catching snow to insulate the plants.
This past winter, the continuous snow cover in Minnesota from late fall to early spring with no winter freezing and thawing provided excellent winter survival. However, if you know the field will be rotated to another crop in the spring, you could harvest at a more typical 2.5- to 3-inch stubble height to gain tonnage.
Smith is the livestock information manager for the northern business unit of Pioneer Hi-Bred. Contact him at email@example.com.
This article published in the August, 2010 edition of THE FARMER.
All rights reserved. Copyright Farm Progress Cos. 2010.