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United States Department of Agriculture

Agricultural Research Service

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Research Project: Establishing New Grain Packing Factors: Field Data from the Western U.S.


2011 Annual Report

1a. Objectives (from AD-416)
Obtain new field data to refine and calibrate a science-based model for determining the packing of grains within upright storage structures. The Cooperator will obtain field measurements of grain packing from the major grain producing regions of the U.S. with collaborators at ARS, the University of Kentucky, and the University of Georgia who will also make field measurements. Field data will be collected for wheat, corn, soybeans, grain sorghum, oats, and barley. The effect of aeration systems on packing factor will also be investigated.

1b. Approach (from AD-416)
This research is part of a larger, nationwide project to refine and validate a procedure with known accuracy, based on measurable physical parameters, for determining the packing of grains within upright storage structures. Because grain is somewhat compressible when subjected to the cumulative weight exerted from the material above, accurate packing factors are required to determine the mass of grain in storage from bin dimensions and test weights. Inventory control is critical for stored grain managers due to financial aspects (auditing by state agencies) and for the future utilization of quality management systems. The major variables affecting stored grain packing are grain type, moisture content, test weight, internal friction, and bin wall material, geometry, and dimensions. Variation across different regions of the U.S. must be investigated as well as other minor factors. A preliminary model for determining packing factors for a wide range of grains and bins is being developed at the University of Georgia that employs the differential form of Janssen’s equation to estimate the pressure and in-bin bulk density for a given depth of grain in a bin. In the larger project, this model will be calibrated and validated by measuring packing factors for selected grains in bins in all of the major grain producing regions of the U.S. As part of that nationwide effort, the Cooperator will measure packing factors in selected states west of the Mississippi River. Field measurements of packing factors will be obtained by measuring the height of grain in bins of known dimensions and wall materials as they are filled and/or discharged with a measured mass of grain.

3. Progress Report
Stored-grain packing factors were measured in more than 40 bins in Kansas, Oklahoma, and Iowa covering a wide range of bin sizes. Bins of concrete construction ranged up to 140-ft deep and those of corrugated steel construction ranged up to 105-ft diameter with 90-ft eave height. The majority of the packing factors measured were for hard red winter wheat and have varied from about 3% in small bins up to about 8% in large bins. The data is being used to calibrate a science-based computer model that is expected to predict packing factors with better accuracy than that achieved by the current method. These activities were monitored via meetings and numerous conference calls with the cooperators to discuss project plans and review program goals and accomplishments, along with personal oversight of much of the research.

4. Accomplishments

Last Modified: 06/24/2017
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