Evaluating the accuracy and efficiency of test weight instruments for soybean (Glycine max L.) research

Authors: FETT, ROBERT - Auburn University; Gillen, Anne; Read, Quentin; PATEL, SEJAL - Auburn University; KOEBERNICK, JENNY - Auburn University

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/23/2023
Publication Date: 3/16/2023
Citation: Fett, R., Gillen, A.M., Read, Q.D., Patel, S., Koebernick, J. 2023. Evaluating the accuracy and efficiency of test weight instruments for soybean (Glycine max L.) research. Agrosystems, Geosciences & Environment. 6:1-8. https://doi.org/10.1002/agg2.20354.
DOI: https://doi.org/10.1002/agg2.20354

Interpretive Summary: The U.S. official soybean (Glycine max L.) test weight (TW) is 75.7 kg hL- 1 (60 lbs bu-1). This standard is used to convert weight of a load of soybean into bushels. Typically, when TW falls below 68.4 kg hL-1, (54 lbs), growers may receive discounted payments. In recent years, the average TW of soybean appears to have declined in certain regions. There is currently no literature on the relative merits of common instruments used to measure TW. Therefore, we compared three instruments: a Mini-GAC Plus, a Perten Aquamatic 5200, and a volumetric instrument, for accuracy and speed of sample processing in a lab setting. The TW of 517 plots generated from 11 soybean field trials grown in Tallassee, AL over two years were measured to compare the performance of these machines. The median value per instrument was used to determine variation and bias among the machines, and the speed of processing 100 samples was used as a measure of efficiency. For accuracy, the Perten had better agreement with the volumetric than the GAC and contained less bias compared to the GAC. All three TW instruments differed significantly from each other in processing speed. The volumetric instrument had the fastest processing speed, but utility was limited due to lack of moisture measurement. Otherwise, the Perten Aquamatic 5200 is more efficient. Future experiments should examine seed quality parameters and how they may influence the measurements of samples.

Technical Abstract: The U.S. official soybean test weight (TW) is 60 lbs per bushel. This standard is used to convert weight of a load of soybean into bushels. Typically, when TW falls below 54 lbs, growers may receive discounted payments. In recent years, the average TW of soybean appears to have declined in certain regions. There is currently no literature on the relative merits of common instruments used to measure TW. Therefore, we compared three instruments: a Mini-GAC Plus, a Perten Aquamatic 5200, and a volumetric instrument, for accuracy and speed of sample processing in a lab setting. The TW of 517 plots generated from 11 soybean field trials grown in Tallassee, AL over two years were measured to compare the performance of these machines. The median value per instrument was used to determine variation and bias among the machines, and the speed of processing 100 samples was used as a measure of efficiency. For accuracy, the Perten had better agreement with the volumetric than the GAC and contained less bias compared to the GAC. All three TW instruments differed significantly from each other in processing speed. The volumetric instrument had the fastest processing speed, but utility was limited due to lack of moisture measurement. Otherwise, the Perten Aquamatic 5200 is more efficient. Future experiments should examine seed quality parameters and how they may influence the measurements of samples. This information will aid soybean breeders and agronomists in selecting the instruments that best suit their research needs.