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Moisture Meter Match
Friday, August 1, 1997
filed under: Harvest/Storage
As good as the best portable moisture meter might be, there’s still a certain degree of “art” in this particular science. “Even in a laboratory setting, if we can get repeatable numbers within 0.1 or 0.2 percent between samples dried in a laboratory oven, we feel we’re doing pretty good,” says NDSU ag engineer Ken Hellevang. That variance “is not the meter’s fault,” he adds. “It’s just the environment in which we’re working. There are so many different factors that affect the readings of these meters [e.g., temperature, type of growing season, drying procedure]. All these things can contribute to variability in the structure of that seed or kernel.”
Given this fact, it’s important for the grower to compare his meter with that used by his elevator. Regardless of how accurate he thinks his own meter may be, what really counts is the reading on the elevator meter.
“Prior to harvest, look at your meter and the procedures you’re using,” Hellevang suggests. After taking a moisture reading on a sample, place the sample in a sealed bag or container and head to the elevator for a comparison. Or, better yet, take your own meter reading from the sample while at the elevator. “Hopefully the two meters will be close; but they’re not going to be exact,” he cautions. Even when drawing two samples from the same five-gallon bucket, there could be some variation.
The NDSU ag engineer also reminds producers that seeds just coming out of a high-temperature dryer will give a lower moisture reading than actually exists. The reason, of course, is that the more-porous, lower-density hull will be drier than the kernel. The moisture will equilibrate (i.e., “moisture rebound”) — but not for several hours.
“I recommend putting the seed sample into a plastic bag or some other type of sealed container; giving it several hours (10 to 12) so the moisture can equilibrate; and then doing the check,” Hellevang states. The result will be a significantly more accurate reading of the entire seed’s moisture content. — Don Lilleboe