Alfalfa Management Practices Aid in Curing Process

Windrow spacing, using conditioners help offset potential losses

DES MOINES, Iowa.– With rising hay prices, growers look to management practices to achieve a high-quality crop. Pioneer Hi-Bred, a DuPont business, suggests growers refine alfalfa curing practices to maintain integrity of harvested hay.

Rapid, uniform curing of alfalfa is most desirable. However, recent research reveals forages don’t dry at a uniform rate. Proper cutting and management practices can help offset curing time and potential quality losses.

“Growers may think when alfalfa has been cut, it’s dead,” says Dr. Bill Mahanna, coordinator of global nutritional sciences for Pioneer. “Those cells continue to live. They’re living, functioning and metabolizing in the windrow until the plant reaches about 48 percent moisture.”

“There are three main reasons for quality loss,” Mahanna continues, “respiration losses in the field, leaf shatter from harvesting equipment and the worst – leaching due to any kind of rain.

Through proper curing practices, losses can be minimized. Alfalfa curing has three phases. The initial and intermediate phases occur rapidly. The final phase takes progressively more time.

“There is a misconception that leaves dry primarily through the surface, but the surface is covered with a waxy cutin layer for protection,” says Mahanna. “The drying process actually occurs through stomates – where the moisture escapes.”

Stomates are openings in the leaves, small holes that act like lungs. Oxygen and moisture exit the alfalfa plant through these holes. Stomates open during the day and close at night.

“In order to keep stomates open and functioning properly, growers need to look at their windrows. If a windrow is narrow and shaded, the stomates will close,” says Mahanna. “In return, you won’t achieve the initial phase of rapid drying.”

Spreading out a windrow creates more surface area for exposure to the sun and wind, allowing stomates to open and facilitate the removal of moisture through the leaves.

“By understanding what those openings do – act like lungs – growers can aid the drying process through good windrow management. This allows moisture to escape and the crop to move into the intermediate phase of drying,” says Mahanna. “At that moisture level, it is safe to silo the hay at harvest.”

Another option for growers is conditioners. A conditioner on a harvester along with a wide windrow is most beneficial when a grower is planning to bale alfalfa for dry hay.

“If growers want dry hay, that’s where conditioners are most beneficial. We still can have the wide windrow, but it helps considerably to utilize a conditioner, so when the stem is crushed there is radial movement of moisture from it,” says Mahanna.