If you have clouds of dust trailing your rake, you're probably adding unnecessary ash to your forage. That can lower its quality and, if it's fed to dairy cows, the amount of milk produced, says Dan Undersander, extension forage specialist at the University of Wisconsin (UW).

A certain amount of ash is unavoidable. Grass plants contain about 6% ash, and alfalfa holds nearly 8%. But the harvesting and handling of hay or silage, on average, adds 4% more ash, for an average of 10-12% ash, according to UW-Marshfield lab results. That's about 2% too much, Undersander believes.

Some results show even higher amounts of ash — one sample contained 18% ash, he says. “That guy was feeding 1 lb of dirt for every 4 lbs of hay. Do you think his cows produced a lot of milk? I suspect not,” he says.

By limiting added ash to just 2%, “you've improved the quality of your product,” Undersander adds.

Here are his suggestions to meet that goal.

  • Cut the crop at least 3-3½" high. “If you cut alfalfa shorter you get a little more tonnage, but as you go below 3", especially when the soil is dry, you're going to be picking up more dirt.”

  • Change your disc mower knives from standard to flat. “The standard knife has a 14-degree angle and it creates a little vacuum. On first cutting when the ground is wet, it doesn't make any difference; on second and third, when the ground is dry, you can easily pick up 1-2% ash.”

  • Switch from narrow to wide swaths if you haven't already.

    “When you go to a wide swath, that swath stays on top of the stubble. If you make a narrow windrow it sinks down onto the ground, and when you pick up the windrow, you see a layer of dirt on the underside.”

  • Keep rake tines from scraping the ground. “It's worthwhile to have a level field,” he adds.

  • Be careful when feeding out of bunker silos on bare ground during rainy weather.

“This is one of the reasons why we've always encouraged people to put their bunkers either on asphalt or concrete,” says Undersander. “Generally speaking, the highest ash contents are from silage taken out of bunkers during rainy weather when a lot of mud comes with it. That's when we'll see ash contents go up to 18-20%. It's only a month or two when it occurs, but it can be a big problem.

“I usually tell people to pay attention to their forage analyses. It's easy during the unloading from a bunker to add 6-8% ash.”

Any ash added above the 4% level indicates a significant problem, he says. That's when harvest and management practices should be reviewed and altered. Now's a good time to look at the ash content of your forages and consider what changes you may want to make to keep total ash content in that 10-12% range, Undersander concludes.