Although anhydrous ammonia costs less, handling and safety problems make propionic acid a better preservative. The recommended application rates for large square bales are listed in Table 1, where the propionic acid concentration is 75 to 80 percent. If the acid concentration is less more chemical will need to be added. Recommended application rates of propionic acid. If the solution contains other acids such as acetic or citric acid, it will be less effective than a solution containing only propionic acid.
Acetic acid is considered to be about one third as effective as propionic acid.
Therefore you would need three times more acetic acid to have the same effect as the recommended rate of propionic acid. For bacterial inoculents, the manufacturer s recommendations should be followed. Costs will be less when the acid is purchased in the off season in large quantities. The key to selecting the correct application rate will be determining the forage moisture content. An accurate method must be used and good representative samples must be obtained.