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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maintenance. Granular matrix sensors measure the electrical resistance between two electrodes embedded in quartz mate- rial and correlate the resistance with the matric potential of the root zone. To calculate irrigation requirements based on volume, soil moisture tension or suction values must be converted to volu- metric soil moisture content using a mois- ture release curve. Dielectric sensors record volumetric soil moisture directly; measure- ments can be affected by the length of the rods, soil texture, soil density, and soil electrical conductivity. Absolute moisture values can vary con- siderably over a landscape. If a sensor is in- stalled in a location representative of an irrigated area, and if it records moisture extraction between maximum and mini- mum over time, using this data can lead to more consistent irrigation scheduling than using absolute values alone. Reported re- ductions in irrigation water applied range from 0% to 82% when soil-moisture- based controllers were used for scheduling compared with either traditional or ET- based irrigation scheduling. Crop water stress indices and normal- ized difference vegetation indices calcu- lated from remotely measured reflectance of canopies have been suggested for irriga- tion scheduling of cool- and warm-season turfgrasses. However, to date no auto- mated remote sensing irrigation scheduling technology based on reflectance is com- mercially available. How do modified root zones and cur- rent water management technologies relate to sports turf? The construction and man- agement of sports fields are directed to support the performance characteristics of safety, playability, durability, and aesthetics at some level of expectation. Water man- agement, as expressed in irrigation, is key to meeting those expectations. Occasion- ally one finds a sport field that has been built by merely scraping off a spot and seeding it. Most often, though, the con- struction involves modifying the root zone in some manner. In either case, the turf manager must learn how to irrigate that field and ensure that the root zone grows the best grass possible. Water management technologies have been developed to make that job just a little easier and to obtain the highest efficiency from the water that is applied. ■ This article was adapted from Turfgrass Water Conservation, Second Edition (Uni- versity of California Agriculture and Natu- ral Resources, ©2011, Regents of the University of California), which was writ- ten by scientists for turfgrass managers and decision makers to address many of the is- sues relating to turfgrass irrigation. This excerpt is used by permission. This publication, along with many other useful resources for the turf profes- sional, can be found at http://anrcatalog.ucdavis.edu/TurfLawns/ www.stma.org SportsTurf 15