Agriculture Reference
In-Depth Information
PC
Network
user
Sensor node
Web server
(data storage)
Gate
way
Field
Central node
Internet
Cellular
modem
Cellular tower
Local wireless sensor network
Long range cellular network
FIGURE 13.4
A hybrid soil sensor network (HSSN) for
in situ
, real-time soil property
monitoring. (From Li, Z. et al.,
Comput. Stand. Interfaces
, available online: May 23, 2011,
2011. With permission.)
A USDA research group was formed to study precision irrigation control of self-
propelled, linear-move, and center-pivot irrigation systems (Evans and Bergman, 2003).
Wireless sensors were used in the system to assist irrigation scheduling based on on-site
weather data, remotely sensed data, and grower preferences. In 2010, a test platform was
established including two WSNs of infrared thermometers to monitor canopy tempera-
ture, which was commonly used as an indicator of crop water stress (O'Shaughnessy
and Evett, 2010). One of the WSNs was installed on the lateral arm of a center pivot
irrigation system and used to monitor crop canopy temperatures while moving. Another
WSN formed by stationary nodes was installed in the field below the pivot to provide
stationary reference canopy temperature. RF modules, XBee (MaxStream, Logan, UT,
USA), were used for communications. An embedded computer was used for recording
and analyzing the collected data and making irrigation decisions.
Kim et al. (2006) developed and tested a closed-loop automated irrigation sys-
tem. The system consisted of in-field sensing stations, an irrigation control station, a
weather station, and a base station. The sensing station and the weather station pro-
vided in-field status readings. The base station collected and processed the in-field
data, made decision on irrigation scheduling, and sent the control commands to the
irrigation control station to control the operations of sprinkler nozzles. The irriga-
tion control station also updated the GPS locations of the linear irrigation system
regularly and sent them to the base station. The wireless communications among the
stations were through Bluetooth technology.
King et al. (2005) developed a closed-loop, distributed control and data acquisi-
tion system for site-specific irrigation management for a center pivots system. The
system was formed by a group of stationary field sensing nodes deployed in a field and
