The operator of the new Case combine purchased by the Purdue University farm system for use at the Throckmorton Research center near Romney this year had to continually return to the grain cart converted into a weight wagon after each 6 row plot at harvest of a large plot last week. It begged the question- was the yield monitor built into the new combine adequate to test the plots, without having to dump each time.
These plots were 105 feet long. the crew concluded that while they were close to being long enough, Jeff Phillips, Extension ag educator in charge of harvest, insisted on weigh them in a weigh buggy. He wanted to make sure that the comparisons were accuratem and was concerned that the plots were too short for an accurate test with the combine yield monitor,
However, the distance it takes to get an accurate test and eliminate the need for a weigh wagon or grain cart with scales may be shorter than you think. The Purdue farm crew at Throckmorton this fall have done unofficial, nonscientific demonstrations, trying to prove to themselves just how long strips must be to get accurate, side-by-side comparisons with the yield monitor Such a system would eliminate lots of time during harvest of plots, and might make it more enticing for farmers to do replicated plots on their own farms.
According to the crew, 50 feet is far too short. They tried 75 feet and still weren't satisfied. Anything longer then 100 feet seemed to produce reasonable results, however. Phillips observations from riding in the cab during harvest of this particular plot, with 105-feet rows, was that he was still more comfortable actually weighing the grain. However, the crew is convinced that at lengths much above 100 feet, the combine yield monitor has time to process and record weights accurately.
What their unscientific testing does indicate is that combine yield monitor should be very adequate for strip trials or replicated farmer plots that are several hundred feet in length. Often, farmers make an entire pass across the field, and use that as the final results. The current research indicates that running strip trials with a combine equipped with a yield monitor should produce very fair comparisons.
The combine was equipped with mapping capabilities, and did map the small plot.