Heavy rains in many areas this spring are splashing more soil onto forage plants than normal. On a forage-quality analysis, that could show up as high ash and skew forage energy and dry matter (DM) intake estimates, says Marvin Hall, forage specialist with Penn State University Extension.

So producers should work to minimize ash amounts at harvest, he stresses.

"The normal ash content of legume-grass forages is near 9% (DM basis). However, in years with lots of rain, forages can contain up to 18% ash. If a dairy producer feeds 25 lbs (DM basis) of forage containing 18% ash, he would be feeding each cow nearly 2.5 lbs more soil each day than normal."

He suggests the following ways to minimize ash content:

  • Keep windrows off the ground. Start with a wide swath and place cut forage onto dense stubble to eliminate harvesting a layer of soil on the bottom of windrows. Putting hay into a wide swath also increases drying rate. "The windrow should be high enough so that it can be raked or merged without the rake touching the ground," says Hall.

  • Keep rake tines from touching the ground. "This can be done if the forage is on top of stubble and the ground is level. Wheel rakes tend to incorporate more ash because they are ground-driven."

  • Minimize moving hay horizontally to reduce stones and other ash. It's better to move two swaths on top of a third in the middle rather than to rake all to one side.

  • Use a windrow merger rather than raking. This produces less ash content since the windrow is picked up and moved horizontally by a conveyer rather than being rolled across the ground. Merging can result in 1-2% less ash in hay or silage.