Ted Funk, U of I Extension Ag Engineer, reports that high propane prices and the possibility of a wet harvest season pose an interesting challenge to farmers who may have relaxed their guard over the last few years when grain drying was not much of a problem. Corn breeders have made life easier with varieties that stand better and dry down faster in the field.

However, it's still very possible that corn will be harvested this fall at well above safe storage moisture, that is, above 15%. If we see stalk lodging or ear drop problems, the harvest timing will be more critical to save the crop, and on-farm drying will need careful consideration.

Let's review the basics of drying, for the sake of planning. Yellow dent corn needs to be dried to below 15% moisture content for long-term storage. Short-term storage of 18% moisture content corn can be safe if grain is cooled below 50 degrees F. The allowable storage time, that is, the days corn can be stored before one-half percent dry matter loss, depends on several factors. For clean corn, the time you can store it is mainly a function of temperature and moisture content, so cooler and drier is better. Corn with lots of broken kernels and fine material spoils faster, as does a crop with weed seeds, insects, and moldy kernels. A rule of thumb is that, for a given moisture content, the allowable storage time for clean grain doubles for every 10 degrees F. that the grain is cooled. Corn at 60 degrees F and 24% moisture content has an allowable storage time of only 10 days, so if you are thinking of natural-air drying in a bin, you have a very brief time to get the job done with that inherently slow process. Compared to high-temperature drying, air-only drying can be pretty tricky because of the spoilage potential. You need to have your homework done in either case, or you can lose a lot of money in a hurry.

Efficiency vs. harvest and drying capacity is a tradeoff. With propane costs several times what they were the last time we had a wet harvest season, it should be worth your effort to watch crop condition in the field and balance field drydown with field losses. Clean, well-maintained drying and storage equipment pays big dividends. If you don't have a checklist for pre-season system tune-up, see your equipment dealer.

High-temperature dryers should be run at rated temperature. Reducing the drying air temperature usually cuts energy efficiency, not the opposite; and lower drying air temperature results in less dryer capacity. Check your manual for recommended operating conditions.

For in-bin low-temperature and natural air drying, airflow is the key. Minimum airflow needed per bushel is based on the average drying air temperature and the grain moisture. Push the limits on grain depth, grain moisture, and/or operating temperature, and you have a formula for a bin of spoiled corn. Do your homework, and make sure you know the limitations of your system. You don't have to guess, but you do have to monitor corn moisture content and weather conditions.

Typical energy used per bushel: MidWest Plan Service MWPS-13, Grain Drying, Handling and Storage Handbook (www.mwps.org) includes a table estimating the relative operating costs for drying and cooling corn from 25.5% to 15.5% moisture content. A high-speed column dryer with in-dryer cooling might be expected to burn 20 gallons of propane per 100 bushel of corn and use 10 kWh of electricity. Contrast that with dryeration, a system that uses delayed cooling in a bin, which could give you 60% higher system throughput while requiring 14.5 gallons of propane and 7 kWh of electricity per 100 bushel of corn dried. At $2.50/gallon propane and $0.10/kWh electricity, the out-of-pocket energy costs for the two systems would be $51 and $37 per 100 bushels of corn, respectively. Combination drying, using a high speed dryer for taking the first points of moisture, and in-bin layer drying to get the last points plus cooling, can increase throughput by about 250% over the high-speed dryer alone, and with 8 gallons of propane and 90 kWh of electricity spent, combination drying might cost about $29 per 100 bushels, or 57% of the cost of high-speed drying with in-dryer cooling.

Review with your employees and family members the safe operation of drying equipment and grain bins. Harvest time is stressful, and everybody involved needs to know the risks of working around grain. Some excellent resources are in the MidWest Plan Service Grain Handling Package. See www.mwps.org or call MWPS at 515-294-4337.