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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.


2010 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
States producing hard red winter (HRW) wheat were ranked based on their total annual winter wheat production (USDA NASS, 2009). Lists of hard red winter wheat varieties produced in each state were obtained from NASS. Varieties that were common to multiple states and/or were available for multiple crop years were given high priority in the selection of test varieties. Other varieties that were popular in specific states were included to provide coverage of all of the leading HRW wheat producing states. Seed producers and vendors with the chosen varieties in stock were identified in each state through various contacts with foundation seed programs and others in each state’s seed industry. The chosen varieties have been ordered and delivered to the University of Kentucky Granular Mechanics Laboratory to undergo compressibility tests. A terminal elevator in north-central Kansas that has an automated system for grain loading and unloading is being used as a test site to evaluate automated data collection. This elevator uses a commercial system that logs all their transaction data for incoming and outgoing grain. A virtual private network (VPN) system was installed in January 27, 2010 in the USDA-ARS lab to remotely collect daily transaction data. The data obtained through the VPN were analyzed to sort out grain bins that were empty and to monitor filling with incoming wheat. A field exercise was conducted at this elevator on June 10, 2010. The height and hopper dimension of empty bins, with heights ranging from 100 to 120 ft, were measured using a laser distance meter. The height and dimension data were used to draw the grain bin configuration in a computer-aided design (CAD) software package. These measurements provided the empty-bin reference values needed to determine grain volume from future loaded-bin measurements. Four bins were measured in the USDA ARS research facility in Manhattan, Kansas on June 10-11, two metal bins and two concrete bins. One lot of wheat was measured in the first metal bin. The lot was moved to a second bin where it was first measured peaked, then was measured again after leveling. A 12,000 bu round concrete bin and 1250 bu square concrete bin, each containing wheat, were measured in the research elevator. All distances were measured using the commercial laser distance meter. The grain height and hopper dimensions of empty bins in the research elevator were also measured using the commercial laser distance meter. These data are being incorporated into CAD drawings to compare filled and empty grain bin configurations, giving accurate grain volumes for pack factor calculations. These activities were monitored via numerous meetings with the cooperator to discuss project plans and review program goals and accomplishments, along with personal oversight of the research, the majority of which was performed in ARS facilities.

4. Accomplishments

Last Modified: 10/17/2017
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