Evaluation of ET based "smart" controllers during droughts
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A smart controller testing facility was established by the Irrigation Technology Center at Texas A&M University in College Station in 2008. The objectives were to (1) evaluate smart controller testing methodology and to (2) determine their performance and reliability under Texas conditions from an "end-user" point of view. The "end-user" is considered to be the landscape or irrigation professional (such as the Licensed Irrigator in Texas) installing the controller. This report summaries the performance of nine smart controllers over an eight month growing season in 2011. Controllers were programmed based on a virtual landscape that evaluated controller performance using multiple plant types (flowers, turf, groundcover, small and large shrubs), soil types (sand, loam and clay), root zone depths (3 to 20 inches) and other site specific characteristics. Controllers were divided into 2 categories, those which utilize on-site sensors to calculate or adjust ET or runtimes; and those which ET values are sent via cellular, radio or the internet. Controller performance was compared to total ETo, plant water requirement (ETc) and the weekly irrigation recommendation of the TexasET Network (http://TexasET.tamu. edu). Results so far indicate that controllers using onsite sensors for calculating irrigation water requirements produced lower water requirements and were more often within the irrigation recommendations of the TexasET Network. Significant seasonal differences in controller performance were also found. Results also indicate problems in quantifying effective rainfall, particularly when using a rain sensor. The 2011 results show controller performance during historic drought conditions.
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