Be pushy if you want accurate moisture readings on your hay, says University of Kentucky agronomist Mike Collins.

Pushy, that is, as in pushing your tester into the hay in several places each time you check moisture.

“Probe several spots on a single bale or probe several bales so that you're testing from different areas of the windrow,” Collins advises. “Moving around and taking several readings prevents one small dry area or wet spot from unduly influencing your results.”

The agronomist says hand-held, probe-type moisture testers are more accurate than they used to be. But it's still important to practice correct probing techniques. To get a dependable moisture value, he recommends taking 10 readings and averaging them.

“Individual readings mean very little,” says Collins. “If you have three to four readings within a bale, you may get numbers that easily differ by up to 10 moisture units.”

His research has shown that it doesn't matter if you probe one bale 10 times or 10 bales once. You'll get roughly the same results because the variability within and between bales is almost identical. But he still recommends probing several bales in case your fields are more variable.

Moisture testers work best when there's close contact between the hay and the sensors, so always probe the densest areas of bales.

“If you have a looser bale and happen to put the probe into an air pocket inside that bale, you'll get an erroneously low estimate of the moisture because the sensors might not come into much direct contact with the hay,” he says.

Most probe-type testers operate on the principle of electrical resistance, utilizing the relationship between the moisture content of the hay and its conductivity. This is possible because moisture is an effective conductor of electricity and hay acts as an effective insulator.

In general, mid-sized and large rectangular bales and round bales are denser than small bales, so it's easier to get accurate readings on them. To remedy potential problems with small bales, Collins recommends probing them while they're still in the baler.

“When the bale is in the slide, it's under pressure from the baler and will be very uniform and relatively tight. Stop the baler and take readings from the bales in the machine.”

If you're probing round bales, it doesn't matter if you sample from round or flat surfaces, he says. However, fixed-chamber-type round balers tend to make bales with looser cores, so probe in the outer foot of those bales.

One final piece of advice: Follow the maintenance protocol included with your tester's operating instructions.

“It's important to remove the plant proteins and other residues that gradually accumulate on the probe because they can affect the contact between your crop and the probe,” says Collins.

“I recommend some type of solvent, such as alcohol, and a soft cloth to remove them.”