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6.
About the LEIT RC2ET Environment Features
Introduction
Today, irrigation use can be optimized through the use of our weather based
irrigation control system developed for landscape irrigation. This can be
achieved by monitoring the soil, temperature, humidity, radiation, rainfall,
wind, and environmental conditions at the irrigation site. Both the plants water
requirements and the amount available to the plant roots can be measured or
estimated through a variety of techniques. These techniques include the feel
method, which is an estimate based on the user's knowledge of the irrigation
site, the more accurate method of utilizing tensiometers, or the use of weather
sensors designed to monitor real time conditions including water demands
influenced by the local environment, the irrigation method and the plant types.
Water Requirements
To simplify the relationships between plants, water requirements and
the environment, the term evapotranspiration is often used. Originally
established for agriculture, where irrigation requirements are well
documented, evapotranspiration measures the loss of water for various
crops planted by farmers. Evapotranspiration takes into consideration the
loss of water from the plant surface, the evaporation of water from the
soil and the water lost through transpiration during a specific time period.
Historical values for many crop types have been recorded and are made
available through agricultural extension services.
Evapotranspiration (ET)
Several methods have been developed to estimate crop ET. Most methods
use weather data to provide an estimate of reference, or potential,
evapotranspiration (ETo). Often this estimate of reference is converted to
"actual" ET using a factor known as a crop coefficient (Kc). In landscape
irrigation, reference evapotranspiration (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 practical due to the large variety of
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