Agriculture Reference
In-Depth Information
water use efficiency (Workneh et al. 2009; Price et al. 2010), and insect infestation
(Mirik et al. 2007; Yang et al. 2009) have been shown to be feasible.
11.4.2 S
ENSOR
N
ETWORKS
Not surprisingly, wireless sensor network (WSN) systems are emerging to facilitate
the implementation of irrigation scheduling. Wireless stand-alone sensors on the mar-
ket include those that measure soil water, air temperature, humidity, precipitation, and
surface radiance (including thermometric measurements—infrared). An array of sen-
sors can be established to monitor crop or soil water status. Soil water sensors were
established as stationary WSN systems and used to spatially monitor soil water content
and trigger irrigations (Vellidis et al. 2008). WSN systems can also be established in
varying soil types to help estimate the amount of irrigation water to apply (Hedley and
Yule 2009) if strategically located in field-mapped electrical conductivity zones. Both of
these fixed sensor network systems offer the potential for reliable remote monitoring of
spatially variable soil water status in cropped fields and integration with a variable rate
irrigation system for site-specific delivery of irrigation water.
WSN systems consist of plant monitoring sensors and a GPS unit deployed onto
center pivot or liner sprinkler systems, in effect become moving WSNs and provide
whole-field monitoring of crop water status (O'Shaughnessy and Evett 2010b) for
irrigation scheduling and control (Figure 11.5).
FIGURE 11.5
Six-span center pivot system with wireless infrared thermometers mounted
off the pivot lateral for monitoring crop canopy temperature as the pivot moves. Wireless
infrared sensors are mounted in front of the drop hoses. (Photo taken during the summer of
2009, Bushland, TX.)
