Baseline Systems BaseStation 6000 - Manual (Page 62)

BaseStation 6000 Site Controller Manual
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5 – ET-BASED WATERING
Evapotranspiration (ET) refers to the loss of moisture from the soil by evaporation and by the transpiration of plants. Factors
such as air temperature, humidity, solar radiation, and wind speed affect the rate at which ET occurs. The BaseStation 6000
system includes advanced ET-based watering technology, which enables ET-based zones to be watered when needed rather
than on a pre-set schedule.
ET-based irrigation systems attempt to calculate the loss of water from the root zone and adjust the watering schedule
accordingly. The first step in this process is to obtain an accurate estimate of reference ET (ET o ). Data for the standardized
reference ET equation is gathered from air temperature sensors, weather stations, or rain gauges. Then the BaseStation 6000
software estimates ET o by plugging the on-site data into mathematical equations (Hargreaves or Penman Monteith).
In addition, the system uses data that you supply about the zone:
• A specific plant type's water needs
• The plant’s microclimate (ranging from full sun to total shade)
• Irrigation method used (spray, rotor, drip, or bubbler)
• Type of soil at the site (clay, sand, or loam)
• Slope of landscape (ranging from slight to extreme)
• The latitude of the site
The BaseStation 6000 system provides several methods for implementing ET-based watering:
• Based on readings from an air temperature sensor
• Based on readings from a weather station such as the Campbell Scientific Evapotranspiration Monitoring Station
• Based on readings from a rain gauge such as a tipping rain bucket
IMPORTANT NOTE: ET-based watering does not take the place of programs on your BaseStation 6000 controller. You still need
to follow the instructions in the Initial Programming and Programming Adjustments sections of this manual to set up your
programs, and then apply the ET settings to the specific zones.