Agriculture Reference
In-Depth Information
adopting the technology. They reported that future application of the wireless tech-
nology could include precise farm management, food safety, traceability of agricul-
tural products along with radio frequency identification (RFID) tags, and ubiquitous
computing. Lee et al. (2010) described basic information of wireless technology
and different applications related to specialty crops and presented the following as
typical applications in agriculture: management of farming, precision agriculture,
optimization of plant growth, surveillance in farms, advertisement for consumers,
education and training for efficient farming, and research. They suggested the fol-
lowing factors to increase adoption of the technology: low cost, easiness, rugged-
ness, long-range communication, and scalability to a high number of sensor nodes.
The following are some examples of the wireless sensor technology. Hamrita and
Hoffacker (2005) implemented a wireless system to monitor soil moisture content
using a microcontroller and passive RFID tags. Vellidis et al. (2007) developed a
WSN for smart irrigation in cotton using moisture sensors, a circuit board, and an
active RFID tag to provide wireless sensor interface. Darr and Zhao (2008) described
a model that can predict losses of wireless transmission signal due to structural inter-
ference and quantify them in a poultry layer facility. Zhang et al. (2011) developed a
four-layer (sensor node layer, gateway, central platform layer, and application layer)
wireless network system, and reported good performance of the system.
4.2.5 Y
IELD
M
ONITORS
Commercial yield monitors are being adopted steadily in the United States, Europe,
and other parts of the world in recent years. Yield monitoring is widely used in
grain harvesting, but yield monitors have been developed and used for non-grain
crops such as cotton, potatoes, sugar beets, sugarcane, forage, and tomatoes. Some
of the commonly used yield monitors include monitoring systems from Ag Leader
Technology (Ames, IA), John Deere (Moline, IL), and Case IH (Racine, WI). The
integration of yield monitors with GPS enables yield measurements to be associated
with their geographic positions for creating yield maps. Yield maps are critical to
precision agriculture because they can be used for determining management strate-
gies and for evaluating the results of these strategies.
A yield monitoring system consists of a display console and a set of sensors
installed on a harvester for measuring crop flow rate, moisture content, ground
speed, and cutting width that are mathematically related to yield. A GPS receiver
is usually used with a yield monitor for yield mapping. Some yield monitors rely on
a header position sensor to accurately calculate harvested acreage. Several types of
flow sensors are used for measuring grain flow, but impact-based mass flow sensors
are commonly used in many yield monitoring systems. Grain flow can be sensed by
placing an impact plate in the path of clean grain flow to measure either the force
applied by the grain impacting the plate or the amount of plate displacement that
occurs when grain strikes the spring loaded plate. The force or the displacement
measured is proportional to the grain flow. A cotton flow sensor uses light emitters
and light detectors mounted on opposite sides of a cotton picker's delivery ducts such
that cotton passing between the emitters and detectors reduces transmitted light. The
measured reduction in light is converted to flow rate. A moisture sensor allows grain
