Preservatives used on hay with 28 percent moisture will prevent mold formation and heating of hay that normally occur at this moisture content. Baling at this higher moisture content will reduce leaf loss in legume hays. So the dry- matter yield and higher protein are advantages of chemical preservatives. Research at Pennsylvania State University has shown an increase of 400 pounds per acre of dry matter with chemical preservatives. Baling at higher-moisture contents will also reduce drying time in the field by several hours, which can help when it's raining frequently.
Propionic acid is dangerous to skin and eyes and corrosive to farm equipment.
You must handle and store it carefully. Buffered propionates are much safer to handle. Rates of propionate vary with the moisture content of the hay. But we don't recommend baling hay at more than 28 percent moisture. Spray propionic acid onto hay as it enters the baler.