Reconditioning soybeans that are too dry causes soybeans to expand, which can damage the grain bin's bolted connections or even cause the bin to rupture from the increased pressure on the bin wall, warns Ken Hellevang, North Dakota State University Extension ag engineer
He suggests several ways to recondition soybeans in storage safely and effectively:
1) Use a negative pressure system to pull humind air down through the soybeans.
2) Remove the soybeans from the top of the bin as they are reconditioned. Grain flows from the top of the bin in a funnel shape as it is unloaded from the center bin sump. Or use a vertical-stirring auger to mix the beans frequently. However, soybeans become more fragile at lower moisture contents, so stirring may damage the beans.
4) Operate fans during weather with an average relative humidity of about 70% to reduce moisture content to 13 percent during normal fall temperatures of 30 to 60 degrees F.
5) Use a humidistat to turn the fan on any time the humidity is above about 60%. Add a second humidistat to stop the fan when the relative humidity reaches very high levels to prevent excessive moisture contents. Or, install a microprocessor-based controller that monitors temperature and humidity, and runs only when air conditions will bring the crop to the desired moisture content. Running the fan only at night when the humidity is higher will recondition the soybeans but does not provide any control options.
6) Use a drying bin that has a fully perforated floor and a fan that can deliver at least 0.75 cubic feet per minute of airflow per bushel. Even with this airflow, moving a rewetting front all the way through the bin may take more than a month of fan operation. Using lower airflow rates to move the rewetting front through the bin will take several months. "Reconditioning time primarily depends on the airflow per bushel and weather conditions," Hellevang says. "Reconditioning occurs the fastest when the airflow rate is high and the air is warm and humid."
For more information see the NDSU Extension Service's soybean production guide or NDSU's grain drying and storage website.