Technical information
www.digcorp.com • 1.800.322.9146
Introducon
The LEIT-2ET system is a weather-based, wireless
irrigaon control system that adjusts user preset daily
or weekly irrigaon programming according to real me
weather informaon provided locally by DIG’s LEIT WWS
or LEIT WWSE wireless solar powered weather staons.
The LEIT-2ET system consists of a two-staon, ambient
light (solar) powered controller with a rain sensor
connecon, an ambient light (solar) powered weather
staon and a two-way, remote control handset. The LEIT-
2ET ambient light (solar) powered, wireless controller
is programmed to monitor, control and adjust irrigaon
schedules for each valve using the weather informaon
received from the LEIT WWS solar powered, wireless
weather staons along with programmed site informaon
received from the LEIT RC2ET remote control handset.
The LEIT-2ET controller receives and stores weather
data from a LEIT weather staon once every hour during
dayme hours from a distance of up to 350 . (100 m)
line of sight. The controller uses the weather staon data
and site informaon provided by the LEIT RC2ET handset
to calculate the hourly and daily local microclimate
evapotranspiraon (ET), and automacally adjusts the
irrigaon schedule.
Today, water use can be opmized through the use of our
weather based irrigaon control system developed for
landscape irrigaon. This can be achieved by monitoring
the soil, temperature, humidity, radiaon, rainfall, wind,
and environmental condions at the irrigaon site. Both
the plants’ water requirements and the amount of water
available to the plant roots can be measured or esmated
through a variety of technologies. These technologies
include the feel method, which is an esmate based on
the user’s knowledge of the irrigaon site, and the more
accurate method of ulizing tensiometers, or the use of
weather sensors designed to monitor real me condions
including water demands inuenced by the local
environment, the irrigaon method and the plant types.
Water Requirements
To simplify the relaonships between plants, water
requirements and the environment, the term
evapotranspiraon is oen used. Originally established
for agriculture, where irrigaon requirements are
well documented, evapotranspiraon measures the
loss of water for various crops planted by farmers.
Evapotranspiraon takes into consideraon the loss of
water from the plant surface, the evaporaon of water
from the soil and the water lost through transpiraon
during a specic me period. Historical values for many
crop types have been recorded and are made available
through agricultural extension services.
Evapotranspiraon (ET)
Several methods have been developed to esmate
crop ET. Most methods use weather data to provide an
esmate of reference, or potenal, evapotranspiraon
(ETo). Oen this esmate of reference is converted to
“actual” ET using a factor known as a crop coecient
(Kc). In landscape irrigaon, reference evapotranspiraon
(ETo) is established for well-watered turf grass, however
most landscape species do not have values established.
The turf and landscape industry’s managers and users
are not equipped to measure the plants’ water loss. The
feel method is not praccal due to the large variety of
environmental and management condions. Due to this
inability to eecvely measure and record water loss for
landscape planng, formulas have been developed using
reference evapotranspiraon, plant factors, microclimate
factors and landscape coecients to esmate the water
used. DIG’s weather based irrigaon controller system
ulizes a version of these formulas as the baseline for
esmang water use.
Informaon from the environment, plant water
requirements and the tools to calculate how much water
is in the soil may help in reducing water use by increasing
irrigaon eciency. By viewing the soil as a reservoir for
the plant’s water, and calculang the daily water needs of
the plant using various crop and landscape coecients,
we can determine approximately how long plants can
survive on the water available in the soil. When the water
in the soil is close to depleon, a med irrigaon in the
proper amount can rell the soil prole, restarng the
cycle.
The Importance of Soil Texture in Seng ET
Before programming the LEIT RC2ET handset and using
the new ET features we recommend that the user read
about soil texture. Knowing the soil type is important
in seng the proper conguraon on the LEIT RC2ET.
Most users can determine the soil type by reviewing the
following:
Radiation
Temperature
Wind speed
Humidity
=
ET
o
ET
o
well watered
grass
grass
reference
crop
BASED ON
x =
ET
c
well watered crop
optimal agronomic conditions
K
c
factor
off