2012 Annual Report
Field, laboratory and computer simulation studies are being conducted to develop improved predictions of stored grain packing factors. We have measured approximately 50 hard red winter (HRW) wheat bins, 30 corn bins, 12 oat bins, 8 soybean bins, and 3 grain sorghum bins across the Central, Midwest, and Southern U.S. for determining packing factor. The overall evaluation of the wheat field data showed that our current packing model based on preliminary tests was slightly under-predicting packing factor and, thus, grain weight. The percentage difference between reported (actual) grain weights and model predicted was always below 8%. However, non-circular wheat bins showed a greater tendency to over-predict. For corn bins, field data showed that the current packing model was mostly under-predicting. The percentage difference between reported (actual) grain weights and model predicted was always below 4%. For the limited soybean bins, field data showed that the current packing model was mostly under-predicting and the percentage difference between reported grain weights and model predicted weights were consistent at 5%.
Twenty-seven hard red winter (HRW) wheat samples were obtained from eleven states in the HRW wheat growing areas of the U.S., composed of eight different varieties covering three production years. Samples were tested at both low (10% wet basis) and high (13% wet basis) moisture content in the laboratory uniaxial compressibility tester to determine compressibility as a function of overbearing pressure. Results showed greater compressibility for low test weight and higher moisture samples, while the differences between varieties and differences between crop years sometimes equaled the test weight and moisture differences. The individual HRW wheat samples were mixed in composite samples, most of which represent mixing that occurs in the grain transportation and handing system. Six composite samples were prepared based on growing state (Texas, Oklahoma, and Kansas) or variety (ART, Jagelene, and TAM 111). Four additional samples were prepared representing multistate regions of HRW wheat production. The composites were tested in the uniaxial compressibility tester at low and high moisture content levels. The general trends with test weight were similar to those with the individual variety samples. Overall, as with the individual variety samples, the higher moisture wheat composite samples showed greater packing than the low moisture samples, which was expected because moisture makes grain kernels more compressible. However, this moisture effect has not previously been included in stored grain auditing methods.
A Windows-based software package is being developed to provide the new packing factor predictions to customers in a convenient format. The second beta version of the grain packing factor prediction software was delivered to the Risk Management Agency (RMA) in mid June, 2012. Phone discussions with RMA officials elicited several desirable revisions to the user interface that are being implemented. This version provides an easier input method then the previous one plus it includes an output form that can be readily printed by RMA users to make a hardcopy of the important results. The software includes preliminary estimates of packing for corn, hard red winter (HRW) wheat, soft red winter (SRW) wheat, soybeans, and grain sorghum. The new packing factor predictions in this software, from the results of this research, should improve grain bin inventory determinations by stored grain managers and official auditors and provide better confidence in the results than was possible with the old methods.