When hay won't field-dry below 18% moisture, most experts say to apply a preservative. Choose one that's high in propionic acid, they advise, and read the label carefully to know how much to apply.

A good preservative, properly applied, controls molds and bacteria that develop when hay is baled and put into storage at 18-30% moisture. These micro-organisms can produce toxins, reduce palatability and cause high dry matter loss.

“That's due to increased plant respiration and microbial activity,” notes Mike Rankin, a University of Wisconsin extension agent in Fond du Lac County. “There's typically a 1% loss of dry matter for each 1% moisture loss during storage.”

The wide variety of products on the market includes inoculants — live bacterial cultures that keep hay from heating by outcompeting spoilage organisms. But they're not used widely on baled hay.

Preservatives containing propionic acid are a better option. They do a good job of inhibiting mold growth when hay is in the 18-30% moisture range. But straight acid products can also be corrosive.

“They can take the paint off a baler in a matter of minutes,” says Jeff Roberts, president of Harvest Tec, Hudson, WI. His company is the country's leading supplier of application equipment for hay preservatives.

The problems with corrosiveness have led preservative manufacturers to develop buffered acid products. Just as effective as straight acid products, buffered preservatives “have become the industry standard against which other preservative products are measured,” says Rankin.

Many buffered products also include an antioxidant.

“Propionic acid is an oxidizer that takes the color and smell out of hay,” says Roberts. “Adding the antioxidant keeps that from happening.”

Around 20 buffered products are currently on the market. While most product labels list the amount of actual propionic acid, users can still find it difficult to distinquish between products.

“Some manufacturers list percentage of acid before the reaction; others state the theoretical level after the reaction and still others list results from a chemical test,” says Roberts.

The U.S. Environmental Protection Agency (EPA) has launched an effort aimed at standardizing labels. “But to this point, enforcement has been pretty spotty,” he adds.

For that reason, Roberts advises concentrating on the label's required application rates.

“A good label lists higher levels of application for large square bales than for conventional squares or large round bales,” he says. “It also lists higher rates of application for hay with stem moisture than for hay with dew moisture only.”

Knowing moisture levels is the key to calculating application rates correctly. Moisture variations of 5-10 percentage points are typical within windrows.

For balers with conventional application systems, your best bet is to stop after making several bales and check moisture with a hand-held electronic tester. Because readings can change quickly throughout the day, you'll want to repeat the process frequently.

“The biggest drawback to hand testing is that the application rate has to be set to cover the wettest part of the hay being baled,” says Roberts. “That can lead to overapplication.”

Relatively new applicator technology featuring baler-mounted remote moisture sensing is an alternative. A remote sensor takes multiple moisture readings every second, then relays the readings to the applicator's control system.

“Application is automatically matched to the condition of the hay,” says Roberts. “You utilize product more efficiently than you would with a standard system, while still ensuring all the hay is treated with enough product to prevent heating.”

Setting up a conventional application system on a baler will cost $800 to $1,200. Adding remote sensing will push cost into the $3,000-4,500 range. In either case, Roberts advises selecting an applicator with a multiple set of spray tips. That will give you more flexibility in adjusting rates as moisture levels change.

“Typically, you'll see a four-fold increase in the application rate when moisture increases from 16% to 30%,” he says. “A single set of spray tips only allows for a doubling of rates.”

America's Alfalfa Brand To Prevail

Alfalfa seed will continue to be marketed under the America's Alfalfa brand, despite the recent purchase of ABI Alfalfa by Land O'Lakes, Inc.

“America's Alfalfa has a very strong product line and a strong customer base,” says Mark McCaslin, president of Forage Genetics International (FGI), a Land O'Lakes subsidiary. “We hope it stays a strong, viable and growing brand for a long, long time.”

The two companies' breeding programs will be combined, and germplasm developed by ABI breeders will be incorporated into FGI's variety development efforts.

“ABI breeders were working on some unique traits that other breeding programs weren't,” says McCaslin. “Grazing tolerance and traffic tolerance are two obvious ones. But they were working on a number of things that we think are very interesting.”