A 6-milileter polyethylene sheet totally encloses the grain to prevent ammonia from escaping. A central duct runs under the center of the grain pile and lateral ducts of 6-inch perforated plastic drain tile are connected at right angles to the central duct. The laterals are spaced 24 inches apart and extend to within 2 feet of the edge of the pile. A flexible return duct is sealed to the top of the plastic cover. A squirrel cage fan powered by an electric motor recirculates ammonia from the flexible duct at the top of the pile, forcing it under the corn through the central duct underneath.
Ammonia is injected into the pressurized duct beneath the grain pile.
The fan and motor should be sized to deliver cfm per bushel treated. Ammonia vapor should be recirculated for about 48 hours. After that time the fan can be turned off except for short periods when it is needed to distribute heat and moisture. The treatment time varies from 1 to 3 weeks, depending on grain temperature and moisture. When sampling indicates that aflatoxin has been reduced to acceptable levels, the return hose can be disconnected and the fan operated to aerate the grain.