Proprionic Acid Hay Preservative

​​​Proprionic acid is commonly used as a hay preservative. However, it is also used a human food and animal feed ingredient. The two formulations of the product are not the same, which has created some confusion among both agribusinesses and farmers. Here are the facts.

Selling Proprionic Acid

You may need a license if you sell proprionic acid. You cannot sell proprionic acid as a hay preservative unless it is registered by the U.S. Environmental Protection Agency as a pesticide and labeled as a registered pesticide. If you sell proprionic acid as a pesticide, you must be certified and licensed by the Wisconsin Department of Agriculture, Trade and Consumer Protection.

Storing Proprionic Acid

Businesses that store proprionic acid that has a pesticide label in containers larger than 55 gallons must follow bulk storage requirements.  The main requirements are:
  • You must store containers inside a secondary containment structure.
  • When you transfer the product from one container to another, you must do so over a mixing and loading pad.

Using Proprionic Acid on Your Own Farm

You may use proprionic acid that is not labeled as a pesticide on your own hay. However, it will not have usage directions or guaranteed effectiveness. If you use proprionic acid labeled as a pesticide on your own hay, you do not need to hold a private applicator license.

Using Proprionic Acid on Hay You Bale for Others

You will need to be certified and licensed as a commercial pesticide applicator if you are a custom hay baler or if, in one calendar year:
  • You are paid to bail hay for more than 3 other farmers, or 
  • You are paid to bail hay on more than 500 acres
You will need to pass the exam for the Field and Vegetable Pest Control certification category, and get a commercial pesticide applicator license and pesticide business license.