Efficiency is one of the key factors to consider in the evaluation of a forage harvester.

Harvester capacity should be matched with the capacity of the vehicles needed to transport forage. Other considerations include cost, reliability, maintenance and repair costs, dealer support, and the ease of operation.

Four self-propelled forage harvesters in the 800-horsepower range were tested for throughput, fuel consumption, and the quality of processing in corn forage. The machines were comparable in fuel consumption per hour of operation.

The Claas machine had the highest throughput; tons of fresh material per gallon of fuel. The John Deere and Krone were comparable. The New Holland machine had the lowest values. 

The measured cut length was significantly different. It was the shortest for the New Holland, equivalent for the John Deere and Krone machines, and the longest for the Claas machine.

Cut length had a significant impact on throughput and fuel consumption. Increasing cut length from 15 to 17 millimeter (mm) increased fuel efficiency by 22 percent measured as tons per gallon of fuel used and a 19 percent increase in capacity, tons per hour.

Processing quality was measured using the Corn Silage Processing Score (CSPS). Although each processor was set at 2 mm, there were differences between the machines. There was no relationship between cut length and any of the CSPS measurements.

The John Deere and Krone machines had significantly higher amounts which did not pass through the 4.75 mm screen. The Claas and New Holland were equivalent and less than the other two. The results mirror other size fractions.

A higher percentage of material was in the medium and fine fractions for the Claas and New Holland harvesters which were equivalent. The Krone harvester had the least amount in the medium and fine fractions. It also had more hours on its fine fractions for the Claas and New Holland harvesters which were equivalent.

The Krone harvester had the least amount in the medium and fine fractions. It also had more hours on its processor than the other machines.

Starch in large particles (more than 4.75mm) is considered to have less nutritional value. The percent of total starch passing through the 4.75 mm screen is optimum above 70 percent and acceptable above 50 percent. Anything below 50 percent would indicate inadequate processing.

The total starch percentage on unshaken samples was equivalent. The percentage of starch that passed through the 4.75 mm sieve was higher for the Claas and New Holland machines, which was the same pattern as the size fraction percentage.

Cut length has a significant impact on fuel consumption and how silage is compacted in the pile, in addition to its impacts on the nutritional value of corn silage.  These factors should be considered in making recommendations and adjustments while harvesting corn silage.

The full paper is available at http://cekern.ucdavis.edu/files/81994.pdf