Dry weather increases the potential for higher ash levels in forages. When high-ash forages make their way into the ration, it could cost you money, says Faith Cullens with Michigan State University Extension.

Watch out for high ash levels in foragesGrass and alfalfa hay typically will have 8 to 10 percent ash. However, ash levels in forages can be quite variable. For example, the ash content of 1,585 haylage samples tested at Dairyland Laboratories, Inc., averaged 11.98 percent ash, but ranged from 6.74 to 17.22 percent.

“If the producer with 17.22 percent ash feeds 20 pounds of this alfalfa silage that is 7.22 percent above expected ash concentrations, there is 1.44 pounds per cow of foreign material going into the total mixed ration,” Cullens says.

“We don’t know what the impacts of soil in the diet are on the cow, such as whether it binds other nutrients, impacts fermentation or accumulates in the rumen,” Cullens says. “But we do know that dirt doesn’t make milk and that it does replace productive nutrients in the diet.”

"There are several preventative measures to avoid contaminating hay or haylage with soil during harvest. Harvesting hay at 3 to 4 inches will optimize forage quality and reduce soil inclusion, especially during dry weather. Using a windrow merger rather than a rake will have less soil disturbance, possibly resulting in 1-2 percent less ash. If a rake is used, ensure the rake is properly adjusted to keep the tines from touching the ground and reduce the amount of soil picked up during hay making. Wheel rakes tend to incorporate more ash than rotary rakes since they are ground driven instead of power driven. Also, using flat mower knives picks up less soil, particularly in dry weather, than curved knives that create suction to pick up downed hay and soil.

"If there is a trail of dust behind the hay making equipment, then there is an opportunity to improve practices to reduce soil contamination in forages. If you haven’t given much thought about the ash analysis of your forages, it would be good to monitor it and adjust your field and farm practices to keep ash content in the normal range," Cullens says.