By Brad Haire
University of Georgia
Radio Frequency Identification helps many retail super centers
track their supplies. It can allow a prescription bottle to
speak to a disabled patient and help pet owners find lost pets.
George Vellidis says it can help a farmer water his crops
better.
RFID is a system that can wirelessly retrieve information from
RFID tags, small devices that contain silicon chips with
antennas, said Vellidis, an engineer with the University of
Georgia College of Agricultural and Environmental Sciences.
The idea of using RFID came up several years ago in a meeting
among engineers in Georgia. Vellidis figured it could be the key
to a system farmers can use to precisely schedule irrigation.
But he and research engineer Mike Tucker could find no published
research on using it for irrigation. So they decided to develop
a prototype system that uses RFID tags to wirelessly transmit
soil moisture data from a field to a central location.
“We wanted to make something workable, wireless, low-maintenance
and relatively cheap,” Vellidis said, “and something that could
relay information in real time.”
Knowing the real-time soil condition in his field can improve a
farmer’s yields, he said, by giving his crops water when and
where they need it. This improves his bottom line and can save
water, too.
Research shows that cotton plants can lose as much as 200 to 300
pounds of cotton per acre if they become water stressed. The
harm can be done before the plants show any signs of damage.
But sometimes the price of knowing may outweigh the benefit, he
said. Commercial irrigation-scheduling systems use nodes with
sensors in the soil throughout a field. The sensors collect data
like soil temperature and moisture. A farmer can manually check
each sensor or have the data sent to a central place. The latter
is more helpful.
But commercial wireless systems can cost $700 or more per node,
Vellidis said. Solar panels are often needed to supply the
power. And systems with wires or cables can get in the way of
farm work.
Georgia farm fields can vary in soil type. Each soil type holds
water differently. To know precisely when and where to water,
farmers need many nodes throughout a field.
The more nodes in a field, the more precise a system would be.
About 20 per 80 acres, Vellidis said, would be ideal.
With RFID, one node in the UGA system costs about $70. That
includes two soil-moisture sensors and two thermocouples for
soil temperatures. A 9-volt battery, he said, would supply
enough power for one season for a watertight circuit board the
size of a playing card.
The circuit board reads the sensors’ data and writes it to an
active RFID tag, made by WhereNet Corporation. The RFID tag has
a flexible antenna a tractor can easily pass over.
A central receiver could wirelessly retrieve the data. The
farmer can use the data to decide when and how much to water.
The system, still in the research mode, isn’t commercially
available. But the projected cost for a 20-node system for an 80-
acre field is about $2,700, Vellidis said, or about $35 per
acre.
The research was funded by Cotton Incorporated and the Georgia
Peanut Commission, Georgia Cotton Commission and Georgia
Research Alliance.
Vellidis hopes the system can become commercially available
through a startup agribusiness. Another product developed on the
UGA Tifton, Ga., campus, called variable-rate irrigation, can
now be bought through a startup company in Ashburn, Ga.
This isn’t the first agricultural use of RFID. Canada uses it to
identify cattle. It can trace a beef carcass at a packing plant
back to its herd of origin. The U.S. Department of Agriculture
is developing its own tracking system using RFID.
