SportsTurf

July 2011

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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FieldScience | Dr. Robert N. Carrow & Dr. Van Cline Precision Turfgrass Management for athletic fields P RECISION TURFGRASS MANAGEMENT (PTM) is a new concept for the turfgrass indus- try; but, it is based on the same principles as Pre- cision Agriculture (PA), which has been evolving since the early 1990’s. Both PTM and PA are based on these foundational principles: • Site-specific management is the first premise of PA and PTM, the application of inputs (water, fertilizer, culti- vation operations, salinity leaching fraction, etc.) only where needed, when needed, and at the amount needed. The idea is to foster more precise and efficient application of inputs by management on a smaller area basis than the current prac- tice, such as at the single irrigation head area of influence or a sub-area on a sports field. • “Intensive” site-specific information is necessary to make wise site-specific decisions. Site sampling is across the whole area, not just selected locations, and on a close sam- ple-grid in order to define the degree and nature of spatial variability for all measured parameters. • Key soil and plant properties must both be measured to allow accurate definition of spatial variability and to allow investigation of the relationships of measured param- eters. For example, PA did not rapidly advance until mobile platform devices were developed that could determine key soil factors that could be related to plant data from remote sensing or crop yield mapping. • Mobile, multiple-sensor devices are necessary to meas- ure multiple factors in a timely manner on a close spacing and across the whole site. Unfortunately, the mobile devices developed for PA are not well-adapted to turfgrass situa- tions, so lack of appropriate devices has hindered PTM de- velopment. • All data are GPS-labeled (global positioning system), which allows the data to be imported into powerful geo- graphic information system (GIS) programs for geostatisti- cal analysis, comparing measured parameters at specific locations, and in order to develop detailed map presenta- tion. Recently, the Toro Company has developed mobile, multiple-sensor units specifically designed for turfgrass sites that supports several PTM field applications that are dis- cussed later (Figure 1, top). The Toro Precision Sense 6000 device has a mapping speed of 2 mph, which covers about 2.5 acres per hour using a grid of 8 x 8 feet sample grid or approximately 900 samples per high school football field. Parameters for Performance Testing of Sport Fields COMPREHENSIVE Site-Assessment parameters that can be determined with mobile PTM devices are noted by a * for currently available devices or with a ** for those with a high potential for a device to be developed in near future. Soil Surface Characteristics. Each determination should be conducted under two field conditions, namely: during dry period with irrigation system is used; and field capacity such after a rain to produce field capacity conditions across the field. • Surface hardness/resiliency (Clegg Impact Tester)* • Surface hardness/compaction. Surface penetrometer (< 1.0 inch)*; deep • penetrometer (4 inch)* • Surface levelness. Any minor or major depressions** • Traction (torsion device with twisting action )** • Shear strength/stress (divot device)** • Soil moisture content – surface 0-4 inches* SOIL PROFILE • Soil type and clay type • Soil physical lab analysis • Profile description. Surface or subsurface layers • Infiltration • Surface drainage – slope, contouring patterns (flat field, crowned, pock- eted); • Subsurface drainage – tiles, slit trenching • Soil fertility tests TURFGRASS COVER • Turf type • Turf uniformity and density** • Grass sward height • Stress indice – NDVI (plant density and color; degree of stress)* • Bare ground – precent, wear patterns* • Weeds – precent and types • Rooting depth • Thatch or mat IRRIGATION WATER AUDIT First Phase – system maintenance • Evaluate and “maximize” system performance • Determine head to head spacing measurements and effect on water distribution* • Determine malfunctioning sprinklers, nozzles, system pressure, head alignment, etc. * • Scheduling settings and capability • Irrigation water quality test Second Phase – water distribution (two options) • Catch-can assessment (traditional water audit approach) – determines water distribution as affected by irrigation system design and performance • Soil moisture distribution based water audit (i.e., new soil water audit approach) using GPS, GIS, mobile sensor platforms* – determine soil mois- ture spatial distribution as affected by irrigation system, soil texture/organic matter content, wind, drainage, and any factor affecting soil moisture content. Fixtures and Surrounds. Factors that may affect player safety. • Goals, fences, etc • Sprinkler placement & maintenance • Surrounds – spatial mapping may be of use in some cases, drainage 16 SportsTurf | July 2011 www.sportsturfonline.com By

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