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How to Dry Soybeans

By Dr. Harold Willis

Soybeans above 14% moisture should be dried. The same drying equipment used for other grains can be used for soybeans. At high drying temperatures (over 100 degrees F.) germination rate, oil and protein quality are harmed. In low humidity weather, no artificial heat may be necessary. If the outside humidity is below 70% and temperature above 60 degrees F., good drying will occur. A perforated floor under the grain gives better air distribution than ducts. An air flow of 2-3 cubic feet per minute is recommended.


To prevent seed coat cracking, drying air should be above 40% relative humidity. The relative humidity of air is approximately cut in half for every 20 degrees F. rise in temperature. Say the outside humidity is 100% at 50 degrees F. If you raise your drying air to 70 degrees F., its humidity will be 50% An additional rise to 90 degrees F. will bring the humidity too low, 25%, and many seeds will crack.

About 2,000 BTU of heat are needed to evaporate a pound of water. You can figure the cost and time for drying a batch of soybeans. Using the accompanying table (below), find the pounds of water per bushel you need to dry, and multiply by total bushels. For example, to dry beans with 16% moisture to 12%, 2.8 pounds of water per bushel must be removed. This times 2,000 BTU equals 5,600 BTU per bushel.

soybean moisture chart

To figure drying time, the BTU per hour equals air flow (in cubic feet per minute) times temperature increase. For example, at an air flow of 2 cfm and a temperature increase of 15 degrees F., the heat input is 30 BTU per hour per bushel. Thus to dry our beans from 16 to 12% moisture, we would need:

drying soybeans equation

If you know the drying time and the horsepower required (see table below), you can figure cost at 1 kilowatt hour per horsepower times electricity cost per kilowatt hour. If a heat source other than the motor and fan is used, the electricity or LP cost must be added on.

soybean drying requirements

Learn more about the specifics of soybean storage here.

Source: How to Grow Super Soybeans