Hay preservatives like propionic acid aren't necessarily going to be a good fit for every hay-making operation. But carefully picking the situations where you use these products could be beneficial, say growers and university forage specialists.

“We'll only use it (propionic acid) on high-quality alfalfa we plan to sell to dairies and only if we think there's a chance the hay will get rained on before we can get it baled,” says Gary Carmichael, owner of Carmichael Farms, LLC, Evart, MI.

Along with the alfalfa, packaged in 3 x 3 x 8' square bales, he also grows grass and alfalfa-grass mixes on 2,000 acres. Markets for the grass and alfalfa-grass hay include alpaca, horse and beef cow operations.

The major advantage of using a hay preservative, says Carmichael, is that he can start baling when hay dries to the 24%-moisture level without worrying about bales heating or developing mold when they go into storage.

“If we can get several consecutive days of good drying weather, we'll let the hay dry down to 15% on its own before baling,” he says.

“But with our weather patterns, getting that kind of weather is tough. We'll have a forecast for several days of sunshine and have the hay drying nicely out in the field. Then the next thing we know, we'll get a revised forecast calling for several days of rain to move in. That's where the propionic acid comes into play.”

Carmichael says the economics of using propionic acid are relatively straightforward. He notes numerous studies showing that hay that gets rained on after cutting can lose as much as 30% of its nutrient value.

“Last year, high-quality dairy hay in our area was selling for $180/ton,” he explains. “If you figure a yield of 2 tons/acre, the value of the hay in a 50-acre field would be $18,000. So losing 25-30% of the nutrients to rain damage would amount to a hit of $5,000-6,000. If you figure the propionic acid cost at around $10/ton, the total cost for that 50-acre field would be about $1,000. It's all a matter of risk assessment.”

Baling at higher moisture can also reduce leaf loss during harvest. “The leaves are where the nutrients are in the hay,” he says. “We also think the acid softens up the hay a little bit and makes it more palatable.”

Increasing the harvest window is another reason to use a hay preservative, says Dwain Meyer, a North Dakota State University agronomist.

“It can be a major advantage in a commercial operation where you might be working a 200-, 300- or 400-acre field,” he says. “If you can start baling earlier in the day and/or continue baling later into the evening, you can harvest more acreage.”

Even so, there are drawbacks to using propionic acid products, Meyer says. One problem: Preservatives can cause hay to lose some of its green color. “That can reduce the value of the hay you're planning to sell in the marketplace.”

While most propionic acid products are now buffered, he notes, hay growers still need to be aware of the potential for corroding balers. “Washing or cleaning equipment after use is still recommended.”

Hay growers thinking about using propionic acid will also need to consider the cost of adding application equipment to their balers. At a minimum, $1,000 or less can be spent for basic equipment like pumps, tanks and hoses and nozzles. “Cost can be substantially higher for more sophisticated equipment,” he says. “But the cost can be recovered quickly if you're able to put up a high-value hay crop without rain damage.”

Meyer's bottom line on using acid-based hay preservatives: “Their greatest potential is for preventing rain-damaged hay or opening up the harvesting window if you're working large acreages,” he says. “As a routine harvesting procedure, the economics are more questionable. If producers can put up high-quality dry hay without using a preservative, they should go that route.”