Agriculture Reference
In-Depth Information
FIGURE 11.2
An automated drip irrigation system for a strawberry experiment. (Photo
taken in March 2009, Santa Maria, CA.)
r A fourth step involves system monitoring to ensure system maintenance.
This is accomplished by supervisory control and remote monitoring to
ensure optimal irrigation.
In a recent strawberry water use experiment, an automated irrigation and chemiga-
tion system was constructed and run for the duration of the study (Wang 2010). The
system layout (Figure 11.2) was similar to the schematic diagram (Figure 11.1) where
the irrigation controller was a CR3000 datalogger (Campbell Scientific Inc., Logan,
UT) programmed to initiate/terminate irrigation events at predetermined water defi-
cit levels [i.e., 3 mm depletion by evapotranspiration (ET or ET
o
)]. Water deficit was
estimated in real time from an on-site weather station (for reference ET or ET
o
) and
concurrent crop canopy measurements (for crop coefficient,
K
c
). The system was com-
pletely stand-alone, from the grower's irrigation operations, where a separate water
storage tank and a generator were used. The datalogger was powered with internal
batteries recharged with a solar panel during daylight hours and the generator during
an irrigation cycle. A total of five separate control systems were used in this setup
because of the experimental needs for different levels and frequency of irrigation.
11.2.2 I
NSTRUMENTATION
General technological advances and demands for automation in pressurized irriga-
tion systems have enhanced the effort in developing necessary instrumentation and
