Forage specialist has advice for managing alfalfa this fall
Dan Undersander, the University of Wisconsin's forage specialist, said that much of the alfalfa in southern Wisconsin suffered from the severe drought this growing season. "A lot of people thought that the drought had broken when we got enough rain to make the grass green again, but in many areas of the state that just isn't true," he shared.
He has gotten many questions from farmers about how to maximize yields for the rest of the year and how best to ensure winter survival of these drought-stricken alfalfa fields.
Farmers have already dealt with the question of how to handle severely drought-stressed alfalfa that was stunted and flowered early. The recommendation was (and is) to harvest full-flower alfalfa if the height is over 10 inches.
If the stand isn't 10 inches tall, it wouldn't economically warrant harvest, he said, and farmers have been advised to just leave it. New growth will come up through that flowering stand after there is some rain.
"Cutting doesn't affect regrowth," he said.
Now, farmers are asking Undersander for advice on handling alfalfa fields for the rest of this unusual year.
Alfalfa should be allowed to go to early or mid-flower when growing again, after rain, to rebuild the condition of the stand. It can be harvested south of Madison as late as Sept. 10 with a good chance for fall regrowth.
But he cautioned that it should not be harvested so late into September that regrowth gets to six or eight inches before frost. If that happens it will use up the carbohydrates in its roots without getting a chance to replenish them.
Farmers are also considering whether or not to take a late fall cutting and Undersander said he's sure that many of the state's dairy farmers will need to try to do that to build up some forage supplies for their herds.
Some years the weather cooperates and that works out well, but it depends on growing conditions.
If the stand condition has been rebuilt and if the variety has a winter survival score of less than two and if the potassium fertilization is up to snuff, he recommends taking a late fall cutting, especially if it is needed to feed livestock.
While there is some risk, the chance of winter injury is less than 20 percent if those previous conditions have been met, he added.
Undersander explained to those on the forage tour during the Agronomy Field Day at the University's Arlington Agriculture Research Station, Aug. 29 that the roots of alfalfa die back over winter and also after each cutting and they need to rebound and re-grow after each of these instances.
The alfalfa stands in the southern one-third of Wisconsin, he said, have probably lost over 50 percent of their yields due to the drought. The heat didn't help either.
There have now been 37 days when temperatures reached 90 degrees or higher. By comparison, 12 days is the number of 90-degree days seen in an average year.
Alfalfa produces the highest fiber digestibility in cooler weather, he said, and this year's higher temperatures produced a 20 percent drop in digestibility.
"The first cutting is always the highest in fiber digestibility and will produce the most milk if cut on time, because it grew under cooler temperatures."
California dairy producers try to buy high mountain hay, he added, because it will be higher in digestibility having grown in the cooler air of the higher elevations.
In addition, the hot temperatures Wisconsin has seen this year serve to bring alfalfa plants into flower sooner, as most farmers in the southern part of the state have noted.
For farmers in southern Wisconsin, given the price of hay and the shortages seen in the marketplace, it will likely pay to cut alfalfa now. Sept. 8-10 is the general time frame that is used to recommend the last cutting, to allow alfalfa plants to rebuild their roots to get through winter.
Then if the weather cooperates and a late fall cutting is warranted that will help build up the feed supplies for the livestock.
"Cut late enough so it doesn't regrow or cut now so it can," he said.
Undersander believes that state farmers "baby" their new seedings too much. At the Arlington farm, he recommends that three-four cuttings be taken and at the Marshfield station two-three cuttings are the norm for new seedings.