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28 LC DBM Many other factors come into play in irrigation system design. Terra Prima ("earth first" in Italian) of Orange County, Calif., recently installed mostly natives on a very large property that needed new landscaping. The irrigation system selected provides overhead watering via spray heads, which, accord- ing to company owner Cherie Ciotti-Roco, is best for California natives. "I did some research and I also spoke to some contractors that do nothing but California na- tives and they all said the same thing" says Ciotti- Roco. "If you install California natives and you use drip lines, they die. The academic explanation for this would be that in nature, they don't get wa- ter dripped on their roots; they get sprayed when it rains." So she specified a 1-inch mainline, ¾-inch later- als, eight valves grouped by sun exposure and 16 to 18 Toro low-flow heads with different throws off of each valve. The installation, whose garden was designed by Rama Nayeri of Creations Landscape Designs, won the Single Family Residence / Green award given by the Orange County chapter of the California Land - scape Contractors Association. Taking Control One of Pacific Green Landscape's key steps in their irrigation retrofit of Westview Neighborhood was to upgrade the old irrigation system to a cen- tral-style smart controller system, which is designed to automatically determine how much water plants actually need before irrigation. Smart controllers are generally broken down into two categories: ET-adjusting and soil moisture sensing. ET refers to evapotranspiration, which is the combined effect of soil evaporation and plant transpiration. ET-adjusting controllers use weather sensors that gauge air temperature, solar radiation, humidity, and wind to estimate how much water is lost through evaporation and transpiration. Soil moisture sensing systems use an in-ground reading of current soil moisture content to estimate the amount available for plant water use. When the available amount drops below a set level, the system directs irrigation to replenish the water. Some smart controllers such as the cloud-based ETwater smart irrigation system wirelessly receive their watering schedules from servers that have ac- cessed local weather and rainfall data and used it to compute evapotranspiration. Toro's Evolution Controller can interface with a weather sensor or a soil moisture sensor. At the Grass Roots Exhibit, the controller is a Baseline model with moisture sensor capability that can handle conventional wiring and a two-wire sys- tem, both of which are being used. Regarding the controller that Pacific Green chose, Top: The U.S. National Arboretum in Washington, D.C., recently opened a turf exhibit titled Grass Roots. The many different areas are irrigated with a wide variety of sprinklers. Here, a Kentucky bluegrass area is irrigated with Rainbird 1800 Series rotary nozzles. Other turf areas (and their accompanying irrigation equipment) include a warm-season/cool-season lawn display with Hunter MP Rotators, a sports field display with Hunter I-20 rotors, and general lawn areas with Rainbird 5000 Series rotors. (U.S. National Arboretum) Above, Left: A portion of the Grass Roots exhibit's golf hole display is irrigated by Toro 570Z Series heads. (U.S. National Arboretum) Above, Right: Toro's Evolution Controller can interface with a weather sensor or a soil moisture sensor to automatically determine efficient amounts of irrigation. A USB port allows for computer setup and updates. (Toro Company)