The two step system works only if flat storage has adequate air flow for drying. Late season drying in flat storage may be slow because of low air temperatures. Before drying Rice should be brought to the dryer as quickly as possible to prevent damage caused by heating during storage in the truck. The first drying pass should begin within 12 hours of harvest. Rice should be aerated if it must be held for more than 18 hours before drying.
Straw can collect in the dryer and block rice flow.
Fines reduce air flow and concentrations of foreign material may cause hot spots in storage. A dryer is controlled by setting air temperature and discharge rate with the goals of operating at maximum drying capacity while maintaining milling yield. Milling yield is kept high by limiting the points of moisture removed per pass. Rice is increasingly subject to cracking with increasing difference between moisture in the center versus the outside of the kernel. Tempering equalizes moisture, so the next pass can safely remove additional moisture.