Based on interviews with agricultural engineers, here's our list of nine key ways to cut drying costs.
Don't harvest corn too early. By delaying harvest in early October by 10 days, corn will dry about .5% per day, or five points, says North Dakota State University ag engineer Ken Hellevang. The rule of thumb for a high temperature dryer is that it takes 0.02 gal. of propane to dry a bushel of corn down one point. The optimal moisture level to harvest corn is 21-22%, Hellevang says. Corn harvested with higher moisture levels than that will have higher drying costs and increased mechanical damage to the kernels, while corn harvested below that will increase field loss, due to stalk breakage. However, once November hits, the economics flip, with corn drying only about 0.2 of 1% per day in the field, and field losses increase.
For growers with a typical high temperature column dryer, the most energy efficient temperature is the highest heat possible without damaging the corn. But the downside in drying corn quickly at high temperatures is that it can be harder on grain quality, says University of Minnesota ag engineer Bill Wilcke.
Recapture heat from air leaving the dryer. There are two options for this. One is to collect exhaust air from the cooling section of the dryer. This can save about 15% on drying cost. The other option, which can save about 20%, uses a housing on the outside of the dryer to capture the air coming off the cooling section and the final portion of the drying column.
Dryeration or high temperature drying followed by transferring hot grain at about 18% moisture content into a steeping bin. Rather than cool corn down in the dryer, the grain is steeped for about six hours in a grain bin with a perforated floor, followed by cooling it with ambient air during which the extra 2-3% of moisture is removed. After a cooling time of 10-20 hours, the corn is moved into a final storage bin equipped with regular aeration fans. Dryeration can save up to 6¢/bu., Hellevang says.
Natural air drying. This may require a new fan, Hellevang says, but natural air drying can cut drying costs in half compared to high temperature drying — 13¢ vs. 6.5¢. Natural air drying is not effective when the temperature drops below 30, however. One option if the corn cannot be dried in the fall is to wait until temperatures warm up to 40 in the spring, but this is not an option for growers who want to market their grain in the winter, Wilcke says.
If looking for a new dryer, important improvements have been made that can dry corn more gently. These improvements include tapered columns in continuous flow units with the upper portion wider than the bottom, Hellevang says. Another feature to consider is the ability of column dryers to move corn from the inside to the outside of the column, which results in more gentle and uniform drying. Features on new dryers that may make them more energy efficient include better moisture measurement so corn is not over dried, more efficient burners and computer controls that permit changing flow rate and drying temperature for more efficiency, Hellevang says. Request documentation on the energy efficiency when purchasing a dryer, he advises, such as BTUs of water being removed at a specified outdoor temperature.
If you sell your corn to livestock producers or to an ethanol plant, check to see whether they will accept wet corn. It's possible you may only have to dry the corn minimally, if at all, Wilcke says. There may be situations where they actually want wetter grain than elevators typically do, he says.
Biomass burners. There is a growing interest in using alternative energy sources for corn drying, Wilcke says, such as biomass burners. While there are no commercial systems available at this time, those with the interest and skills can put burners that are powered by corn stalks or other biomass in front of drying fans to cut energy costs. Farmers may need to buy a heat exchanger to match a biomass burner with a grain drying system, he notes.
Buy propane in summer. For farmers who can buy and store large quantities of propane, discounts may be available for buying in summer vs. fall and winter, Wilcke says.
Plusses And Minuses Of Natural Air Drying
- Requires less equipment.
- Doesn't slow harvest.
- Produces better quality grain.
- Uses less natural gas at harvest.
- In many years, drying is not complete before winter.
- Years with unusually warm weather lead to rapid mold growth.
- Corn moisture needs to be less than 23% for safe, full-bin drying.
- Natural air drying increases electrical demand.
SOURCE: UNIVERSITY OF MINNESOTA