Microwaves Sense Grain Moisture
December 31, 2001
A new technique that uses microwaves to determine moisture
levels in grain crops has been developed by Agricultural Research Service scientists in
In the new process, an antenna transmits microwaves into grain
such as corn, wheat, barley or soybeans. The microwaves pass through the grain
and are received by another antenna. The microwaves' altering as they pass
through spells out how much moisture is in the grain. The new procedure
automatically adjusts for different types of grain.
ARS engineer Stuart O. Nelson, visiting scientist Samir Trabelsi
and retired electronics engineer Andrzej Kraszewski developed the technique at
the ARS Quality Assessment Research Unit in Athens.
Grain moisture is important because the level of water in grain
is a key factor in determining when harvest should occur.
If harvesting occurs when moisture levels are too high, the
combines can damage the grain in the threshing and shelling processes. If the
moisture content is too low, there is the risk of damage from shattering and
kernel breakage. Moisture information is also essential in determining whether
grain can be safely stored without spoilage and in determining the selling
Using current technology, a separate calibration must be
developed for each kind of grain, and corrections are required for differences
in temperature of the grain and its bulk density. In many instances, samples
must be collected and tested in handheld moisture testers or taken to grain
elevators for more accurate testing. The new technique eliminates the need for
multiple calibrations and compensates for grain density and temperature.
The new technique has potential application for use on combines
and on grain handling or conveying equipment and provides for continuous
moisture monitoring. Grain farmers and handlers could then have better
information for managing their operations. If commercialized, the system is
expected to be cost-effective because no other sensor is needed for density,
and calibration maintenance is simpler.
ARS is the chief scientific research agency of the
U.S. Department of Agriculture.