SportsTurf

August 2012

SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.

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Irrigation&Drainage Smart irrigation controllers evaluated by Texas A&M T Year 2011, Result S1," along with Charles Swanson. The report was prepared for Task 2 of the Rio Grande Basin Initiative Irrigation Tech- nology Center, Texas AgriLIFE Extension Serv- ice. This material is based upon work supported by the Cooperative State Research, Education, and Extension Service, US Department of Agri- culture. Fipps is Extension Program Specialist, and Professor and Extension Specialist, Biologi- cal and Agricultural Engineering, Texas A&M. Swanson is AgriLife Extension landscape irriga- tion specialist at Texas A&M. A smart controller testing facility was estab- HESE RESULTS courtesy of Guy Fipps, PhD, one of two authors of the study, "Evaluation of Smart Controllers: lished by the Irrigation Technology Center at Texas 2008 in order to evaluate their performance from an "end user" point of view. The end-user is considered to be the landscape or irrigation professional (such as a Licensed Irrigator in Texas) installing the controller. Controllers are tested using the Texas Virtual Landscape which is composed of 6 different zones with varying plant materials, soil types and depths, and pre- cipitation rates. This report summarizes the results from the A&M University in College Station in 2011 evaluations, when nine controllers were evaluated over a 152-day period, from April 11-May 29, 2011 and August 8-November 20, 2011. TOTAL IRRIGATION AMOUNTS • When looking at seasonal irrigation amounts for the entire landscape, one con- troller was within +/- 20% the recommenda- tion of the TexasET Network for all six stations during the Fall Evaluation Period. • Two controllers applied more than ETo for all three seasonal periods. • Seven controllers applied more than a simple ETc model (ETo x Kc, neglecting rain- fall) for one or more seasons. (across all 6 stations) to adequately meet the plant water requirements for any season. • For all seasons combined, 51 stations ADEQUACY ANALYSIS • No controllers were consistently able Controller performance was analyzed for each seasonal period (spring, summer, fall). Controller performance is evaluated by comparison to the irrigation recommendation of the TexasET Network and Website (http://texaset.tamu.edu), as well as for irriga- tion adequacy in order to identify controllers which apply excessive and inadequate amounts of water. Programming smart controllers for specific site conditions continues to be a problem. Only two of the nine controllers tested could be programmed directly with all the parameters needed to define each zone. 32 SportsTurf | August 2012 www.sportsturfonline.com (37%) showed adequate irrigations, 48 stations (35%) showed excessive irrigation amounts and 39 stations (28%) irrigated inadequately • Four controllers had five stations that pro- vided adequate amounts of water for one or more seasons. • Factors that could have caused over/under irrigation of landscapes are improper ETo cal- culations and insufficient accounting for rain- fall. However, 2011 was a drought year with only 5.45 inches of rainfall. ET values recorded off the controllers were inconsistent and erratic throughout the study. • Based on 2011, performance, controllers with on-site sensors generally performed better and more often irrigated closer to the recom- mendations of the TexasET Network than those controllers which have ETo sent to the controller. While water savings shows promise through the use of some smart irrigation con- trollers, excessive irrigation is still occurring under some landscape scenarios. WHAT'S EXPECTED OF SMART CONTROLLER The term smart irrigation controller is com- monly used to refer to various types of con- trollers that have the capability to calculate and implement irrigation schedules automatically and without human intervention. Ideally, smart controllers are designed to use site spe- cific information to produce irrigation sched- ules that closely match the day-to-day water use of plants and landscapes. In recent years, manufacturers have intro- duced a new generation of smart controllers which are being promoted for use in both resi- dential and commercial landscape applications. However, many questions exist about the performance, dependability and water savings benefits of smart controllers. Of particular con- cern in Texas is the complication imposed by rainfall. Average rainfall in the State varies from 56 inches in the southeast to less than 8 inches in the western desert. In much of the State, sig- nificant rainfall commonly occurs during the primary landscape irrigation seasons. Some Texas cities and water purveyors are now man- dating smart controllers. If these controllers are to become requirements across the state, then it is important that they be evaluated formally under Texas conditions. CLASSIFICATION OF CONTROLLERS Smart controllers may be defined as irriga- tion system controllers that determine run- times for individual stations (or "hydrozones") based on historic or real-time ETo and/or addi- tional site specific data. We classify smart con- trollers into four types: Historic ET, Sensorbased, ET, and Central Control. Many controllers use ETo (potential evapo- transpiration) as a basis for computing irriga- tion schedules in combination with a root-zone water balance. Various methods, climatic data and site factors are used to calculate this water balance. The parameters most commonly used However, many questions exist about the performance, dependability and water savings benefits of smart controllers. Of particular concern in Texas is the complication imposed by rainfall.

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