Agriculture Reference
In-Depth Information
Real-time wireless network systems have been developed for fixed and moving
irrigation systems (Camilli et al. 2007; Kim et al. 2008; Pierce and Elliot 2008).
Wireless technology is preferable because it can avoid problems and expenses related
with deploying and maintaining cables across a field or among moving machinery.
11.5 AUTOMATION WITH SSI
The objective of SSI is to manage irrigation water application to subareas of a field called
management zones to increase crop yield and/or quality, increase water use efficiency,
increase net return, and/or reduce environmental impact. One key elemental difference
with SSI compared to conventional precision agricultural management with fertilizer,
pesticides, and/or seeding rates is that irrigation occurs frequently throughout the grow-
ing season; 40 center pivot sprinkler irrigation events or more can easily occur annually
in arid regions. The frequency of irrigation multiplied by number of management zones
makes automation for SSI management a virtual requirement to accommodate the com-
plexity and labor required. The basic required elements for implementation of SSI are:
(1) an irrigation system with the capability to control water application on a small area
basis called a control zone, (2) an automated control system that can regulate the volume
of water applied to each control zone, (3) a map that relates prescribed management
zone water application to the automated control system control zones, and (4) in case of
moving irrigation systems such as center pivot or lateral move sprinkler systems, some
technique to locate the irrigation system on the map. Theoretically, SSI can occur with
any type of irrigation system that has the basic elements listed above. However, control-
ling volume of water applied to small field areas (management zones) with surface irri-
gation is difficult to implement and achieve. Thus, SSI is most applicable to pressurized
irrigation systems such as micro- or sprinkler irrigation systems. Center pivot sprinkler
irrigation systems have been the focus of most research and development studies for SSI
management and will be the primary focus of this section.
Implementation of SSI management requires determination of timing and amount
of water to apply to each management zone multiple times a week throughout the
growing season. The effort required to make SSI management decisions also virtually
necessitates use of an automated data collection system to accommodate collection of
soil or plant water status needed to make the required determinations for each manage-
ment zone. The automated data collection system can be separate from the irrigation
control system, but from a practical and economic viewpoint, it is more advantageous
to use the same communications system for both functions. The repetitive nature of
irrigation scheduling involved with SSI makes it amenable to using a set of decisions
to automate the complete process. Automation encompassing data collection, decision-
making (irrigation scheduling), and irrigation system control constitutes a decision
support system for SSI. Development of SSI decision support system(s) is currently an
SSI research topic worldwide.
11. 5.1 S
ITE
-S
PECIFIC
I
RRIGATION
Research and development of SSI for center pivot and lateral move sprinkler systems
began more than 20 years ago (Fraisse et al. 1992; McCann and Stark 1993; Camp
