November 5, 2009
The speed (or lack of) of grain drying is certainly one of the critical elements making for harvest concerns this year. Last week, a grain drying webinar was held and I thought I'd pass on some of the info discussed there. First, there is a recording of the program as well as the power point slides available at the following address. www.grainnet.com/webinars
-The speaker (Dr. Dirk Maier, Kansas State) emphasized that you don't have to dry corn to 15% moisture this fall to safely store it.
-To improve grain drying efficiency, the use of 2 stage (or combination) drying systems should be utilized. With this method, you dry corn down to 19-20% then transfer to another bin, where you allow it to steep (sit) for 6-12 hours, then air it. This allows the grain mass to become more uniform in moisture (the speaker mentioned that grain exiting a dryer will vary widely in moisture, even though the average moisture is low). After the 6-12 hours, turn on the air (need near 1cfm/bushel airflow) to remove another couple of points out of the grain, and you can safely store 16-17% corn for 280 days at 40 degrees or 130 days at 50 degrees. But since you'll be airing the grain to take it down to 35-40 degrees for winter, you'll not have any loss. Then take advantage of spring warmth to get the grain down to 14-15% for storage into summer.
-Remember to take the center out of the bin to removing the fines and broken kernels to improve air flow. Don't forget to level the bin after this to improve air flows.
Rules of thumb-
-this fall you'll need lots of air and energy and time
-the higher the air drying temp the faster the drying time- however don't take more than 5 points of moisture out of corn per hour, or you'll lose quality
-the wetter the corn, the higher temp you can use without damaging the grain- you can use heat as high at 200 plus degrees on corn 18% or higher without damaging, as the maximum kernel temperature would only get to 140 degrees or so. However, if you continued drying down past 18% with this high of heat, you'd damage the grain. So his recommendation was to dry down to 18% then transfer to a bin to steep and then air.
-to check airflow, purchase a static pressure gauge and measure static pressure at the plenum and then contact the fan manufacturer with that info and they can tell you how much airflow you have.
-for frost damaged corn, if test weight above 50# (if it was dent before frost), harvest at 30-35% and dry down and then sell before spring as you probably don't want to try and store this corn long term.
-according to North Dakota, we might see up to 1% moisture loss per week with field drying in Nov. but Dec may only be 2% for the whole month.
Regarding natural air drying corn at various moistures and relative humidities and temperatures- Natural air drying is or will shortly be almost nonexistent due to cooler temperatures. The main criteria is the amount of air you can provide. Air flows as high as 1cfm/bushel are ideal. Many bins can't provide that sort of air flow. Using the following chart, at 40 degrees air temp and 50% humidity, it will take 14.4 days to dry 18% corn to 15%.
-Cooler temperatures are probably going to favor us by allowing higher moisture corn to be stored for longer periods of time. For instance, 24% moisture corn can be safely stored for 40 days at a temperature of 40 degrees, but only 15 days at a temperature of 50 degrees. We have available the chart showing approximate storage days at various temps and grain moistures.
- Also remember to check the condition of the grain regularly. There are numerous reports of grain going out of condition already this year.