ALFALFA STANDS BATTLING COLD TEMPERATURES TOO
Many areas of Wisconsin lost alfalfa stands last year due to the cold, wet weather of late winter and early spring around the state. That has meant many dairy farmers have had to scramble for alternative feeds for their herds since the haylage piles have been so much smaller for the feeding season. Farmers are anxiously watching the winter weather and are hopeful the bitterly cold temperatures in December and much of January won’t lead to another extensive round of winterkill across the state.
According to Dr. Dan Undersander, UW-Madison Forage Specialist there shouldn’t be a problem At the recent Agronomy Update and other forage meetings around the state , Undersander said he’s not worried about the cold taking out alfalfa stands, “because of the good snow cover we have across the state that’s protecting the plants.” As long as the snow stays, he said, the alfalfa should be in good shape. He reminded producers that the years when winterkill has been a problem in Wiscosnin was when there was little or no snow cover.
The key to alfalfa surviving the winter is the temperature of the crown of the plant which is two to four inches below the soil surface. If the temperature at that level gets to about 13 degrees the alfalfa will die if the temperature stays that cold for about three to four hours. That, Undersander says, shouldn’t happen this year because “snow is a tremendous insulator that protects the plants from the outside air temperature.”
Earlier this month the soil temperature at four inches on bare ground fell to seven or eight degrees, Undersander reported. But “that was still about 30 degrees warmer than the actual air temperature”, he added. Under the snow cover the four inch soil temperature during the recent cold snap was 28 to 30 degrees, meaning the snow was insulating the ground to another 25 to 30 degrees higher than the air temperature. Added together, that means the ground, under the snow, was about 50 degrees warmer than the air temperature, providing a safe environment for the alfalfa plants. Undersander said that’s why he’s confident the alfalfa, up to this point of the winter is doing well.
The importance of the continued snow cover is that it prevents frost from penetrating deep into the soil taking soil temperatures down with it. When soil freezes it seldom falls below 26 or 28 degrees, Undersander told his audiences, if there is a snow cover, because, “snow cover always trumps air temperature” he said.
During his presentations, Undersander reminded the farmers that survival depends on keeping temperatures above 15 degrees at the crown not at the regrowth of the plant. As long as there is as little as four inches of loose snow on the ground, it will insulate up to 16 degrees of air temperature and since there is much more than four inches of snow cover across the state, our stands are doing well as we get ready for the next cold round of weather.
Undersander also told farmers not to be concerned about alfalfa stands smothering under heavy snows as the stems will stand up through the snow cover and provide air to the plants as they poke through the cover. The same, he said, can’t always be said for grassy stands or pastures as grasses tend to lay over and can smother under heavy blankets of snow.
The deep snow cover should also provide a benefit in the spring as the lack of a deep frost layer should allow the melting snow to soak into the ground and not run off causing spring floods. Farmers are hoping to replenish their hay supplies this year after a year in which many saw their hay mow floors for the first time in a long time as hay stocks were severely shortened in 2013.
Reports from around the country indicate there are other areas as well, especially California, where alfalfa hay supplies will be tight and prices will go up. One California dairy farmer told us their ongoing drought in the nation’s leading milk producing state is forcing them to scramble to find milk quality alfalfa for their cows. They are looking to go to states like Nevada and Oregon for their alfalfa supplies and they expect prices to go as high as $400 a ton delivered to their farms.