Assessment of Yield Monitoring Equipment in Determining Moisture and Yield of Forage Crops.

Whole farm evaluations have shown that accurate yield data for forages grown on farms are most difficult to collect, especially for alfalfa (Medicago sativa L.) and alfalfa/grass fields. In addition, on-farm research, a recommended tool for adaptive management, is hindered by lack of a practical way to collect yield data for farm-scale plots. In recent years, forage yield monitors have become available. Currently the monitors are primarily used for corn (Zea mays L.) silage harvest. The purposes of this project are to (1) evaluate the accuracy of yield and moisture sensing components of forage yield monitors on choppers for the use of alfalfa/grass and corn silage, and (2) evaluate the potential for their use with on-farm strip trials. Eleven farms collected data in 2013 related to yield monitor evaluation including: moisture data, mass flow weights, total area harvested and total dry yield per hectare.  Samples were collected at the bunk and analyzed for percent moisture to compare to the yield monitor output. Truck weights were used to compare the yield monitor yield value to actual yield on two farms for alfalfa/grass and three farms for corn silage. The moisture sensor was able to estimate moisture to within 3.7%DM for alfalfa/grass and 3.0%DM for corn silage. For overall dry yield, the monitor estimated alfalfa/grass yield ±0.5% Mg DM/hectare and ±1.1 Mg DM/hectare for corn silage. When calibrations are done regularly, forage yield monitors can provide an accurate and precise measure of dry yield, but may not be feasible for on-farm research.