Moisture content is best measured by taking a sample from the windrow and drying it using a microwave oven or small commercial convection ovens. Wet and dry weights can be taken with a gram scale. Effect of bale moisture on application rates of propionic and propionic-acetic acid preservatives. Acid preservatives are best applied at the baler. Propionic and acetic acids are volatile and will be lost if applied long before baling.
Acids remove paint, allowing metal parts to rust.
To reduce rusting, avoid spilling acids on equipment, run untreated hay through the baler after baling, and coat bare metal with light oil. Research in Wisconsin shows these products are less effective than propionic acid preservatives. These products are restricted for use on hay of less than 25 percent moisture, but hay can be safely made at 20 percent moisture with no preservative. This narrow moisture range limits the usefulness of these products under Missouri conditions. Bales treated with preservatives are extremely heavy and, in most instances, they need to be handled mechanically.