Performance testing of sports fields is becoming more common to quantify surface properties, such as hardness. Many testing devices now incorporate a Global Positioning System (GPS) and Bluetooth capability to georeference field management locations and send the data to a computer or tablet/phone device. Maps can be created from collected data using Geographic Information Systems (GIS) to visualize the variability (i.e. differences) of a certain property across a field. Maps are gaining increasing attention in the sports turf industry, with several private testing companies incorporating them in their consultation with sports turf managers. However, for you, the sports turf manager, little is known about how they are created and what their practical uses are. This article will discuss in general how maps are made, five ways maps can be used, and the future of maps in the sports turf industry.
Maps are typically made from point data, where each point represents a specific latitudinal and longitudinal location on a field. Determining the latitude and longitude of a given point is called georeferencing and is done using a GPS device. Data that is collected at that location for a specific surface property can be stored within the point using Geographic Information System (GIS) software. Figure 1 depicts maps for five surface properties on a high school football field: volumetric water content (i.e. soil moisture), penetration resistance (i.e. soil compaction), normalized difference vegetative index (NDVI; i.e. turfgrass health), surface hardness, and turfgrass shear strength. The Google Earth images on the left show the points where data were collected and stored for each measured property. The soil moisture, soil compaction, and turfgrass health data were collected using a mobile multi-sensor sampling device, the Toro Precision Sense 6000. The surface hardness and shear strength data were collected using a handheld Clegg Impact Tester and Shear Strength Tester, respectively. All point data were georeferenced using a GPS device.
Once point data are collected, there are multiple methods to create maps using GIS software, all of which use some form of spatial interpolation. Spatial interpolation uses a mathematical formula that estimates values at locations that were not measured, based on the surrounding values at locations that were measured. The result is a continuous surface that shows the variability of a given property across the field, or in other words, a map. Maps are not limited to these five properties. Any quantifiable measurement can be made into a spatially interpolated map.
Now that you have a map, what can you do with it?
Note: Maps can also be created using remote sensing techniques that include thermal heat or NDVI images. Maps made using remote sensing are often used in turfgrass management. Although this article will not discuss remote sensing maps, their application is similar to spatially interpolated maps.
Implementing site-specific management. Site-specific management (also referred to as Precision Turfgrass Management) is perhaps the most commonly suggested use for maps in turfgrass. Site-specific management simply involves the application of inputs (such as water, aerification, and fertilization) only where, when, and in the amount needed. This fosters more precise and efficient application of inputs. Current management practices are often based on recommendations designed to provide good results under average conditions over large areas. Athletic field managers frequently use high amounts of resources in order to achieve a safe, predictable outcome. However, this type of management does not take into account the variability of certain measured quantities (i.e. soil moisture, soil compaction, etc.) that may exist within or between fields.
Site-specific management focuses on managing athletic fields on a smaller scale than current practices. This method helps identify site-specific management units (SSMUs) so managers can target “troubled” areas (high or low values). Focusing efforts on smaller areas may reduce management inputs, improve turfgrass uniformity (above- and below-ground), increase the efficiency of management tactics, and enhance turfgrass longevity/stress tolerance.
Whether you manage 10 fields or one field there are certain benefits for conducting site-specific management. There are many site-specific applications for athletic field maps: a.) soil moisture maps can detect deficiencies in irrigation systems down to a single head; b.) soil compaction maps can be used to create a site-specific cultivation plan; c.) turfgrass health maps can identify wear/stress patterns that alert managers to rotate field use; and d.) overlaying maps of different variables may highlight imperfections in current management practices or underlying agronomic issues.
Demonstrating sustainability. Terms like “going green” and “eco-friendly” will soon become common lingo among athletic field managers. Public concern over the use of pesticides and synthetic fertilizers on sports fields and recreational areas has intensified over the past decade. As societal pressure increases for the conservation of energy and natural resources, attempts to implement site-specific management and reduce inputs may become key to increasing the credibility of sports facilities attempting to become “sustainable.” Improving field playability and athlete safety through the implementation of site-specific management would further exhibit social sustainability of sports fields by improving player satisfaction. Maps can play a critical role when trying to communicate athletic field efforts of sustainability to the public.
Explaining field closures. Athletic field management often involves more than just taking care of the field. Interacting with coaches, players, and administration may be common and at times difficult. Questions often arise when fields need to be closed for inclement weather or maintenance practices. Sometimes telling them that the field is “too wet” is just not enough. Numbers and data can be confusing for some, but maps are somewhat easy to understand. For example, the bright red color depicting stressed turf on a turfgrass health map is an easy way to highlight areas that need special attention or justify closing/rotating field use.
Proposing new equipment or renovations. Maps can easily highlight deficient areas within a field or across multiple fields within a sports complex. Athletic field managers may be cognizant of these areas, while their administrators are often unaware. Maps can be employed to justify the purchase of new equipment or utilized to rationalize the need for future renovations.
Conducting research. Although maps by themselves are aesthetically informative, it is important to note that there are data attached to them. Geostatistics are used to analyze and interpret spatial (through space) and temporal (through time) data, which is essentially the point data from which maps are created. Researchers often conduct small plot (≤ 100 ft2) studies to simulate real world scenarios such as the effect of wear and compaction on athletic field turf. However, data generated from small plot research may have limited application. Geostatistical analysis is conducted at the whole-field level allowing investigators to evaluate “in position” research. At the University of Georgia we use mapping and geostatistics in our research to evaluate sampling procedures, to test the effectiveness of site-specific management techniques, and to determine correlations between player injuries and field surface properties at the exact locations that injuries occur.
Future of maps in sports turf management
Mapping technology is making small, but significant strides in turfgrass management. This is evident with the recent increase in GPS-equipped testing devices and independent companies that provide mapping services. However, adoption and use of maps among sports turf managers has been slow for several reasons. Primarily, educational opportunities to train managers about sensor technology and data collection are very limited. No standards for sampling protocols have been published, because very few universities have conducted research using mapping technology. A lot of the research conducted within our group at the University of Georgia is focused on improving this scenario.
Secondly, testing devices and the accompanying software can be expensive and difficult to obtain. This may be the case for some time until the technology becomes more prevalent and affordable. Lastly, sampling can be a time consuming practice for larger facilities. It takes two people from our research group approximately 1 hour to collect 120 surface hardness samples with a Clegg Impact Tester on an American football field. This could extend to hours or even days for multi-field facilities with limited labor. Mobile sampling platforms can increase sampling efficiency, but very few devices are available for use in turfgrass. In agriculture, sampling devices have been incorporated into a variety of farming equipment. Future research should examine the merger of sensor technology with daily turfgrass maintenance equipment (i.e. mowers, aerators, rollers, etc.) in order to make data collection on athletic fields more efficient.
Even with these current challenges, maps still provide the most detailed analysis of athletic field properties when compared to other performance testing methods. Mapping technology and associated educational opportunities will continue to advance in the future. Maps will become an integral component of athletic field management as the industry begins to focus more on environmental sustainability and player safety.
The authors would like to thank Stephen Richwine, Sports Turf Manager, Oconee County School District, and Joe Morgan, Sports Turf Manager and Groundskeeper III, University of Georgia Facilities, for use of their facilities. Thanks are also extended to Troy Carson, Kathy Rice, and Van Cline, The Toro Company, for technical support with the Precision Sense 6000.
Chase Straw is a graduate research assistant, University of Georgia; Dr. Gerald Henry is an Athletic Association Endowed Professor, University of Georgia.