When the Precision Planting/ Indiana Prairie Farmer plots were harvested recently, all data was taken from the yield monitor. It's part of the Trimble system in a Case 5088 combine with a six-row cornhead.
These plots were at the Throckmorton Ag Center, part of the Purdue University research farm system. The combine is used exclusively on the Throckmorton farm, and land operated by its farm crew.
The farm crew spent time once they purchased the new combine figuring out how long plots had to be before it was accurate if they used the yield monitor instead of the weigh cart. Their conclusion was that for anything just over 100 feet long, the yield monitor information was accurate. The plots in the Precision Planting study were 165 feet long. Each 'plot' in the replicated trial represented 0.06 acres, or a slightly larger area.
The farm crew at Throckmorton reports that they spent considerable time calibrating the yield monitor this fall before beginning harvest. They used the yield monitor data and did not use weigh wagons on a field-size plot for one of the leading researchers who does plots at the farm. He approved of using the yield monitor data in his work.
Despite this there are those who still prefer to use weigh wagons, and who balk at the idea of going by yield monitor data when weighing anything, especially plots where comparisons are going to be made between hybrids, varieties or farming practices, conclusions drawn, and recommendations formulated.
The key is calibration, Jeff Phillips believes. He is the Extension ag educator in Tippecanoe County, and made the decision to use the yield monitor. Phillips is confident that the crew has the unit dialed in and that the strips were long enough to produce accurate results.