Electronic, hand-held moisture meters are not consistently accurate. These meters usually have a bale probe and windrow probe, and they depend on electrical conductivity between points on the probes. Inconsistent readings can occur when testing hay crops with relatively dry leaves and dry outer stems, but wetter inner stems. If such a problem occurs, a bale probe may give readings between 4 or 5 percentage points too low at the time of baling, depending on drying conditions and grass content.
Generally, the windrow probe has proven more accurate than the bale probe when it is used just prior to baling on a sample from the damper, bottom-side of the windrow.
However, the microwave oven and gram scale method of determining moisture
appears to be the most accurate of all (see the accompanying description).