Reducing the amount of ash taken up with forage at harvest should be a priority for growers, said Dan Undersander University of Wisconsin extension forage specialist.

“Dairymen are more and more concerned about the ash content of their hay. It provides minerals but no calories, so the concern is that ash takes the place of nutrients on a one-to-one basis: One percent ash is 1% less TDN. Nutritionists are trying to squeeze every bit of energy they can into that ration and if that cow’s eating an extra pound of dirt, that’s one less pound of nutrients. And that’s less milk,” he said.

“When we look at samples that come into our forage testing labs, hay samples are running about 10% ash on the average. Grasses contain about 6% ash, so they have about 4% dirt. You all ought to be able to put up hay with about 2% ash.” One sample tested 18% ash, he added. “This man was feeding his cows almost 1 lb of dirt for every 4 lbs of hay. Do you think they were going to milk very well?”

Wide swathing creates less ash content in forage than narrow windrowing because wide swaths lie on stubble while fuller windrows sag to the ground, research has shown.

When using disc mowers, growers should pay attention to cutting height. “Our data has shown that for alfalfa, the lower you cut the more yield you get. But, clearly, as we cut below 2½”, we’re going to be picking up more dirt, especially on second and third cuttings when the soil is dry.”

If a grower’s market is particularly sensitive to soil contamination, he should consider using flat rather than angled knives on disc mowers, he added. An angled knife helps pick up the hay, but it also picks up more soil than a flat knife.

Wheel rakes, because they are wheel-driven, can easily add ash to hay, Undersander said. “So it’s important that you adjust the wheels so that they will float as much as possible and still pick up your hay.” Parallel and rotary rakes, in comparison, are power-driven and their teeth can be kept off the ground more easily.

Windrow mergers pick up hay and move it, but growers again have to be sure they’re not also incorporating soil when picking up the windrow, Undersander said.

Read more coverage from the National Alfalfa Symposium...