Protect grain from the heat
Check grain every two weeks during the summer, advises Ken Hellevang, North Dakota State University Extension grain specialist.
Mold growth and insect infestations occur rapidly this time of the year. An insect infestation can go from only a few bugs to a major infestation in less than a month.
• Extra management is needed to store grain over the summer.
• Aim to keep grain cool to slow mold and insect growth.
• Cool grain at the top of the bin every two to three weeks.
He offers the following six tips on checking and managing stored grain in the summer:
• Use insect traps or place grain samples on white material to aid in looking for insects.
• Measure the stored grain temperature at several locations near the top surface, along the walls and several feet into the grain. “Temperature sensors are an excellent tool, but remember that they only measure the temperature of the grain next to the sensor,” he says. “Since grain is an excellent insulator, the grain temperature may be much different just a few feet from the sensor and not affect the measured temperature.”
• Record the measured temperatures. Rising grain temperature may be an indicator of an insect infestation or mold growth. “The goal for summer storage should be to keep the grain as cool as possible to limit insect activity and reduce the potential for mold growth. Insect reproduction is reduced at temperatures below about 65 to 70 degrees,” he says.
• Do not warm grain using aeration during the summer. Aeration fans should be covered to prevent wind and a natural chimney effect from warming the grain.
• Cool grain near the top of bins every two to three weeks by operating the aeration fan for a few hours during a cool morning. Using positive-pressure aeration to push air up through the grain enables the cool grain in the bottom of the bin to cool the air and exhausts the warm air from the grain out the top of the bin. Only run the fan a few hours, or just long enough to cool the grain near the top surface. Running the fan more than necessary will warm more grain at the bottom of the bin, increasing the potential for storage problems. Cover the aeration fan when it is not running.
• Ventilate the space between the grain surface and bin roof. A galvanized bin roof absorbs large amounts of solar energy during the summer, heating the air above the grain. Convection currents flow up along the bin wall and down into the grain near the top middle of the bin, drawing this heated air into the grain. Natural ventilation to cool this space can occur if the bin has openings near the eave and peak in a manner similar to ventilating the attic of a building. The heated air rises and exits near the peak, drawing in cooler air near the eave. This natural ventilation will not occur unless the bin has adequate openings at both the eave and peak. Roof exhaust fans also can be used to draw the heated air out of the bin if it has openings to allow air into the area above the grain. Removing peaked grain reduces the potential for grain warming at the top of the bin. A cone-shaped peak has a larger ratio of surface area to grain quantity, which leads to more warming of the grain, than the cylindrical shape of leveled grain.
Source: NDSU Extension Communications
This article published in the July, 2010 edition of DAKOTA FARMER.