By Emily Glunk, Montana State University Extension Forage Specialist
In alfalfa, some two-thirds of the crop’s nutritive value is in its soft, fragile leaves, making leaf retention through drydown, baling and beyond critical in delivering quality animal feed. So, what steps should you take to get the most from your crop while maximizing leaf retention?
1. Choose the Right Conditioner.
Mechanical conditioning is one of the biggest issues when it comes to maximizing leaf retention during alfalfa harvest.
“The type of conditioner you use can make a big difference [to the health of your crop],” Glunk says. “Flail conditioners that ‘scratch’ the surface of the plant are more suited to grasses, while roller conditioners are more suited to alfalfa. Roller conditioners will crimp the forage … and reduce leaf loss. They have been found to dry alfalfa quicker than flail conditioners, retaining more leaf tissue, and, therefore, more quality in the bale.
“Make sure your roller conditioner is properly adjusted and operating efficiently, and shoot for about 90% of the stems to be ‘cracked,’” Glunk continues. “Slower rollers also help in alfalfa to avoid too much leaf loss.”
2. Rake at the Right Time.
When it comes to raking, moisture is the thing to watch. Try to rake when crop moisture levels are at 40% or above to prevent leaf loss.
“In arid environments, a lot of producers try to not rake at all so they don’t have the associated leaf loss,” says Glunk. “The type of rake can play a role, too. Recent research has found that mergers and rotary rakes have much more leaf retention compared to ground-driven wheel rakes and sidebar rakes,” she says. “While [merger and rotary rakes] are more expensive, it may pencil out in the end.”
3. Size Your Windrows.
Windrow size can have a significant effect on drydown, and therefore leaf retention and hay quality.
“The wider the windrow, the better,” Glunk says, although size can also be affected by climate. “This is mainly due to quicker drydown times, which will retain more nutrients.
“If your windrow is too dense, it is harder for sunlight and air current to penetrate through, which is important in the drying process.”
4. Bale at the Right Time.
Bale size has a big influence on what’s the best moisture level at time of baling. In most cases, the smaller the bale, the higher alfalfa moisture content.
“For something like a small square, we can go at a little higher moisture without worrying about heating and mold formation,” says Glunk. “Typically, we are shooting for between 16 and 18%.” For a large round bale or large rectangular bale, she advises around 14% moisture content. “If we get much below 12%, we will see significant leaf loss occurring,” she adds. “If we are too close to 20%, we significantly increase the risk of molding and heating.”
If you do bale when your alfalfa has a higher moisture content, you run the risk of premature spoilage. That risk can be minimized through the addition of a hay preservative. Applying a preservative to hay baled at up to 30% moisture helps prevent mold growth and heat buildup, both major causes of spoilage.
Also, consider your climate. If you’re in a more arid environment, you can boost leaf retention by baling at night, when moisture is more likely in the field. If you face more damp conditions, it’s best to bale during the day when hay moisture levels are closer to the ideal range.
“Once hay is cut, the plant has begun drying, and the drier it is when you bale, the more likely you are to lose leaves during that process,” Glunk says. “Remember the ideal moisture range when determining when to bale, day or night.”
5. Watch Mother Nature.
“The biggest thing to think about is how weather is going to affect your alfalfa. A slow, [lengthy] but light rain may have more negative impacts than a quick and heavy rain based on previous research,” Glunk says. “The farther out from harvest the precipitation occurs, the more of a negative impact it will have. If you know rain is coming Wednesday and your only options are to cut either Monday or Tuesday, harvesting Tuesday will have less of an impact on [quality] than harvesting Monday.”
While controlling the weather is impossible, there are new tools that can help you maximize alfalfa leaf retention by conducting field operations under optimal conditions. Weather tools offered by the National Oceanic and Atmospheric Administration (NOAA), Weather Underground and even Google, for example, help you keep an eye on the right time to get into the field or harvest.
With a little prevention and the right tools, you can maximize leaf retention, thereby maintaining a quality alfalfa crop. “We can’t control things like the weather,” says Glunk, “but we can monitor conditions closely, and with the right equipment and management, we can maximize the quality of our alfalfa.”
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