Mower-conditioner Adjustments for Rapid Forage Drying in the Field

Ronald T. Schuler, Extension Agricultural Engineer

Two types of conditioning systems used on mower-conditioners are rolls and impeller. The conditioning roll clearance and pressure must be adjusted to insure the stems are cracked which increases the drying rate of the stems. Since the stems dry slower than the leaves, the stem cracking is the important indicator of proper conditioning. At least ninety percent of the stems should be cracked. Another method of checking roll adjustment is to measure the clearance, which should be between 1/16 and 3/32 inch. When the crop is high yielding and has thick stems, the 3/32 inch adjustment would be most appropriate. For low yield cuttings and fine stems, the 1/16 should be considered.

Machine operators should also check operator’s manual for proper adjustment of the conditioning rolls. In one case the manufacturer recommends adjusting the clearance with the machine operating at slow PTO speed while tractor and machine are stationary. They suggest reducing the roll clearance until vibration and/or noise occur and then increasing the roll spacing to a specified point beyond where vibration and/or noise are eliminated. Most machines will have an adjustment at each end of the rolls.

The roll pressure also needs to be sufficient to crack the stems. For high yielding crops, creating a thicker mat of forage moving through the rolls, higher pressures are required. Excessive pressure can cause undesirable leaf loss. Spring tension is adjusted to change roll pressure.

On impeller conditioning systems, the conditioning is due the rubbing or abrasion caused by the impeller fingers. Most of these machines have an adjustable deflector above the impeller which influences the degree of contact between the forage and impeller. When adjusting the deflector down, the degree of forage conditioning will increase. Nearly all the harvested stems should exhibit some mechanical abrasion.

Placing the crop in a swath as wide as possible will take advantage of the sun to dry the crop rapidly. For a twelve foot cutting width, laying the crop in a nine-foot swath will reduce the drying time by about 35 percent compared to laying it in a six-foot swath. Under typical Wisconsin weather, drying time can be reduced up to 6 hours. Nearly all mower-conditioners have adjustable swath forming shields at the rear of the machine for this easy adjustment. Also the machine must be operated so that the swath is uniform. The operator can minimize starting and stopping by following a good maintenance program.

These mower-conditioner adjustments will reduce the risk of poor quality forage. Any steps that reduce the drying time are very important to harvesting high quality forages in Wisconsin weather conditions.