Immature corn  will have trouble drying down, says North Dakota State University  Ag Engineer Ken Hellevang, and it will have low test weights and potential ear molds. He says the only way to stop those is either drying or ensiling. Here are more tips:
1. Standing corn will only dry 0.6-0.9 percentage points per day, even with a warm temperature and a dry breeze, but that rate quickly declines with the calendar. Field drying is more economical until mid- to late October and mechanical high-temperature drying is more economical after that point says Hellevang.
2. Corn above 21% moisture should not be dried using natural air and low-temperature drying to minimize corn spoilage during drying. Hellevang recommends an airflow rate of 1.25 cu. ft./minute/bu. (cfm/bu.) to reduce drying time. Adding heat does not permit drying wetter corn and only slightly increases drying speed.
3. Shelled corn can be stored in a grain bin at moisture contents up to about 25% if it is kept below 30° F using aeration. Corn kernels above about 25% moisture may freeze into a clump that causes unloading problems.
4. Use the maximum allowable drying temperature in a high-temperature dryer to increase dryer capacity and energy efficiency. Be aware that high drying temperatures result in a lower final test weight and increased breakage susceptibility in the corn.
5. Dryeration will increase the dryer capacity about 50-75%, reduce energy used by about 25% and remove about 2-2.5 points of moisture (0.25% for each 10° the corn is cooled). Hellevang says with dryeration, hot corn from the dryer is placed in a dryeration bin with a perforated floor, allowed to steep for four to six hours without airflow, cooled and then moved to a storage bin.
6. Using the maximum drying temperature that will not damage the corn also can reduce energy consumption. The amount of energy required to remove 1 lb. of water is about 20% less using a drying air temperature of 200° F than 150° F.
7. The estimated quantity of propane needed to dry is 0.02 gal./bu./point of moisture removed. Propane will cost about $53 to remove 10 percentage points of moisture from 120 bu. of corn using $2 propane.