Crop Processor Adjustment for the 2006
Corn Silage Harvest

Ronald T. Schuler, Extension Agricultural Engineer

The proper adjustment of the crop processor and forage harvester cutterhead for the 2006 corn silage crop will be very dependent on the degree of crop moisture stress during the growing season. These crop stress conditions in Wisconsin may cause crop conditions to vary from no ears on the corn stalks to small cobs and kernels to normal cobs and kernels depending on the precipitation during the 2006 growing season.

The primary adjustments of concern are the clearance between the processing rolls and the theoretical length of cut for the cutterhead. The primary purpose of the crop processor is to break the kernels and eliminate circular cob pieces. Also, these adjustments need to address the animal ration needs for feed particle size and to insure good fermentation in storage which is dependent on the type of storage.

For a normal crop that has experienced little or no moisture stress during the growing season, the crop processor should be set from one-eighth to three-sixteenths of an  inch to insure proper cob and kernel breakage. The theoretical length of cut should set at three-quarters of an inch. Some producers and custom operators have set the theoretical length of cut to one inch or more. This will lead to faster roll wear and an increased risk for blockage as the crop entering the feed rolls. Also the larger length of cut will create storage removal problems, especially in the upright sealed storage silos.

For the corn silage crop stressed to the point where the kernels and cobs are significantly smaller than normal, the roll clearance should be reduced sufficiently to break the kernels. This may require a clearance of less than one-eighth inch. With this smaller clearance the risk of crop blockage in the processing rolls is greater. The machine operator should consider a shorter length of cut such as five-eighths of an inch to reduce this risk.

For a corn silage crop without ears, it may appear that the crop processor is not needed because its primary function is to break kernels and cobs. Although not reported in research, a secondary benefit of the crop processor in normal crop conditions may be breaking the stalk pieces. Since a greater percent of the nutrients for the animals will be in the stalk for a corn crop without ears, it may be more beneficial to break up the stalk pieces using the crop processor to improve digestibility. The clearance adjustment to consider is one-eighth to three sixteenths. The suggested theoretical length of cut is three-quarters inch.

No matter what the corn silage crop condition is, the crop processor should be very beneficial if properly adjusted. With the moisture stressed crop, proper adjustment will be more important.