Factors that Affect Packing During Storage

There is almost no information in the literature on the effect of storage time on grain compaction in bins. However, this issue is a major concern for grain storage managers who must work with stored grain inventories subject to compaction changes over time from a few days up to a year or more. They are extremely interested in concrete scientific information about changes in grain compaction as a function of time with and without aeration effects. Grain storage managers often report compaction changes due to time in storage and from the effects of aeration; the very limited information in the scientific literature (a single study) supports those observations. Thus, the objectives of this study are: 1. Determine the effect of time under compression (up to 12 months) on grain compressibility in laboratory compressibility experiments. 2. Evaluate the effect of short- and long-term storage (1, 3, 6, and 12 months) with and without aeration on grain compaction for major crops in the U.S. during storage. 3. Evaluate the role of load/unload cycles and settling on packing. 4. Use the discrete element method with grain contact model to develop a methodology to characterize and predict compaction factor for grains including long-term storage and aeration effects. Approach Grain packing in bins is defined as the increase in grain bulk density caused by compression of the cumulative weight of the overlying grain. A computer model for determining packing factors for a wide range of grains and bins has been validated by this research team and is currently in use. The major variables used in the model that affect stored-grain packing are grain type, test weight, moisture content, bin wall material, and bin geometry and dimensions. The major additional complicating factor is time in storage, in conjunction grain aeration, but there is no conclusive data in the literature on the magnitude of this factor. Data will be gathered from laboratory bins at the University of Kentucky, commercial, and on-farm bins, as well as from laboratory compressibility boxes, to evaluate the change in grain compaction with time. Collaborators will also be sought with larger bins of wheat and corn; these crops are sometimes stored for up to six to eight months on-farm and collaborators will be sought who store for over six months. Packing values will be measured immediately after loading and at monthly intervals in all tests. Tall bins (85 ft) at CGAHR will also be monitored on a daily basis for the first week and weekly for the first two months. Measured values of packing each month will be compared to the initial values using a t-test. The correlation of the measured values with time will be determined if the changes are significant. Resulting correlations will be added to the current packing factor computer model.