University of Nebraska-Lincoln Extension, Institute of Agriculture and Natural Resources

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September 28, 2007

Planning for Temporary Grain Storage

If grain has to be temporarily stored outside, ensuring that the area is well drained and that the grain stays dry can help maintain its quality.

Temporary storage may be needed this year until grain can be moved into more permanent storage or sold. There are several options when considering temporarily storing grain. (The following story is being reprinted from the October 22, 2004 CropWatch.)

Modifying Existing Farm Buildings

If temporary/emergency grain storage is needed, putting a crop in a building is better than putting it out in the open. If bin space is full, pole barns and machine sheds can provide good grain storage if they’re prepared correctly and not overloaded. An excellent reference on modifying buildings is North Dakota State University publication AE-84, Temporary Grain Storage by Kenneth J. Hellevang.

Buildings used for grain storage should be in a well-drained site. Lay a sheet of 6-mil or heavier plastic on the floor to reduce the migration of moisture from the soil or through cracks in concrete floors into the grain. Ordinary machine sheds are not designed to withstand the pressures that are exerted on the sidewalls by piled grain. Avoid piling grain more than two feet deep against the side walls of machine sheds.

One good temporary grain storage solution is to construct a temporary “bin” inside an existing shed using steel grain bin rings placed on the concrete floor. These rings are self supporting and are made to withstand the stresses imparted by grain. A temporary “bin” 36 feet in diameter and 8 feet high will hold 6,514 bushels level full and if peaked to the maximum height 7.6 feet above the top ring (total height 15.6 feet high) would hold nearly 8,600 bushels.

Outside Storage

Table 1. Conversion factors for calculations on grain resting at the angle of repose Crop Avg. Filling Height Base Angle Factor Factor (HF) (BF) Barley 28 0.2659 17.95 Corn (shelled) 23 0.2122 22.52 Oats 28 0.2659 17.95 Grain Sorghum 29 0.2772 17.24 Soybeans 25 0.2332 20.49 Sunflower (non oil) 28 0.2659 17.95 Sunflower (oil) 27 0.2548 18.76 Durum Wheat 23 0.2122 22.52 Wheat 25 0.2332 20.49

If grain must be piled outside on the ground, drainage is crucial. The pile should be on high ground with the earth crowned under the pile. Placing plastic on the ground is absolutely essential to keep soil moisture from migrating into the grain. Pile only dry grain (not more than 14% moisture). Cooling the grain with aeration prior to piling improves the chances for success. If the grain will be stored for more than a month, cover the pile with plastic to shed precipitation.

Since site preparation is so critical, it would be useful to know the size of pile necessary to store a given quantity of grain. Grain that is elevated using an auger and then dumped into a pile will come to rest in a cone-shaped pile and will come to rest at predictable angles, as shown in Table 1. Since volume is a function of the height and diameter of the cone-shaped pile, one can estimate the required diameter of a pile of grain necessary to hold a desired quantity (bushels) of grain provided the angle of repose is known for the particular type of grain.

The author has worked out a simple equation which can be used to predict the diameter of a conical pile of grain to hold any given quantity (bushels) of grain. Only two variables are necessary for the computation: the number of bushels and the base conversion factor (BF) from Table 1.

For more information on computing bushels of grain in various situations and configurations, including extracting cube roots, see Lancaster County Extension Factsheet 297-01, Emergency/Temporary Grain Storage - Unconstrained Piles of Grain, at http://lancaster.unl.edu/factsheets/FieldCrops/297.pdf.

Thomas Dorn
Extension Educator based in Lancaster County

Example 1 One could use the equation -- D (ft) = (Bu x BF) 1/3 -- to estimate the diameter of a conical corn pile necessary to contain 10,000 bushels of corn. D(ft) = (10,000 Bu. x 22.52)1/3 = 60.8 feet Example 2 The process of solving for the diameter of the pile also implies the height of the pile necessary to contain the stated number of bushels. However, at times it is useful to estimate the height of a pile of grain once the diameter is known. This will determine the minimum height the auger must be set in order to create the pile of grain. The height of a pile of corn 60.8 feet in diameter can be estimated by multiplying the diameter by the height conversion factor (HF) from Table 1. H(ft) = D(ft) x HF = 60.8 ft. x 0.2122 = 12.9 feet To create a conical pile of 10,000 bushels if corn that slopes all the way to the ground with no walls requires that the site be 60.8 feet in diameter. The auger used to pile the grain must be long enough to reach out 30.4 feet beyond the wheels when at a height of greater than 12.9 (13) feet.

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