Trails of dust behind haymaking equipment signal trouble for dairy producers wanting to minimize ash levels in their rations, warns Faith Cullens, Michigan State University Extension dairy educator.
“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,” says Cullens. “But we do know that dirt doesn’t make milk and that it does replace productive nutrients in the diet.”
Dry weather increases the danger that alfalfa and grass hay will test higher than the normal 8-10% ash, she says. “Any more than 10% ash in a forage sample can be considered contamination from external sources, primarily soil added during hay harvesting or heavy rain splashing soil onto the leaves.”
To avoid contaminating hay or haylage with soil, she says to leave a 3-4” stubble and use a windrow merger instead of a rake. If a rake is used, be sure it’s properly adjusted to keep the tines from touching the ground. Wheel rakes tend to incorporate more ash than rotary rakes since they’re ground driven. Also, flat disc-mower knives pick up less soil, particularly in dry weather, than curved knives that create suction to pick up downed hay and soil.
“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 advises.