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.
Issue link: https://read.dmtmag.com/i/34725
FieldScience >> Figure 2. SOIL HARDNESS determined by the Toro accelerometer presented in standard de- viation format maps that illustrate the lowest and highest hardness areas in a field. These can often be related to soil moisture and traffic patterns. Blue dots are irrigation heads. current time. However, in recent times the term “performance test- ing” has been used to describe assessment of surface conditions of sport fields. Regardless of the terms used, a common theme of almost all sur- face characterization research to date has been to sample only 4 to 6 sites on a sports field due to: the necessity of using several individ- ual hand-held instruments to obtain the necessary multiple soil and plant information; difficulty in inserting hand-held instruments into the soil surface; and high labor/time/cost requirements for sampling which precluded closer grid-sampling. These limitations are reflected in current approaches for performance test- ing such as the PASS system which is low tech but also results in much less information. An exception of using only a few sample sites is a study by Miller on hardness of soccer fields where an 80 sample grid was used and geostatistical analysis techniques were applied, but only Clegg Impact hard- ness was measured. There has also been the occasional use of mobile spectral reflectance devices to determine plant performance primarily as NDVI across the whole sport field surface area, but without associated soil data. The PTM approaches and technology pro- vide the opportunity for performance testing to evolve to a more geospatially precise assessment of sports field playing surfaces along with better mathematical treat- ment of relationships of measured parameters and detailed GIS-based visual presentations in spatial maps (Figure 2). An overview of the site information obtained in a comprehen- hand-held devices that have been used for surface assessment. Of the soil surface characteristics, soil hardness, traction, and shear strength are the most important factors for player safety and playability. Soil hardness as determined by a Clegg Impact Tester or by penetrometer resistance is a function of soil moisture (most important fac- tor), compaction, percent clay, thatch/mat, and soil organic matter content. As soil moisture de- creases below field capacity, soil hardness dramati- cally increases. Thus, spatial variability in soil hardness should first be determined under normal irrigation conditions during dry periods since uniformity of irrigation water application, as af- fected by system design and scheduling, dramati- cally influences soil moisture spatial distribution, and thereby, soil hardness. But, to determine how soil hardness is affected by traffic-induced soil compaction, data should be obtained at field ca- pacity, i.e. to eliminate the influence of irrigation system on soil moisture uniformity. Soil com- paction spatial variability is a function of traffic patterns, soil type, and soil structure. Traction and shear strength are also strongly affected by soil moisture as well as grass type, degree of coverage, thatch/mat/OM content, soil texture, and soil structure (compaction). Thus, traction and shear strength should also be determined under both drier and field capacity con- ditions. Because soil moisture has such a dominant influence on soil >> Figure 3. SOIL MOISTURE variability of a soccer field pre- sented in standard deviation format to reveal the areas with the lowest and highest soil moisture (see std dev legend). The arrow identifies irrigation head No. 13. hardness, traction and shear strength, a new, soil-water audit ap- proach is especially useful for investigating the spa- tial relationships of soil moisture level versus these surface characteristics (Figures 3, 4). The new water audit is based on spatial mapping with the Toro Precision Sense 6000 of soil VWC during a dry-period when the irri- gation system uniformity of water application would be exhibited. In contrast to the traditional catch-can audit, the soil VWC-based audit consid- ers any factor influencing soil moisture distribution sive, sports field site-assessment can aid in understanding how PTM concepts and technology can be integrated into performance test- ing. Henderson and Stiles et al. provide excellent reviews of various 20 SportsTurf | July 2011 (irrigation system design and performance, wind distortion, runoff, high ET areas, etc.) and mapping is of the whole area and surrounds if necessary. A proprietary GIS-based software program allows geo- statistical analysis of spatial variability of soil VWC and other meas- ured parameters as well as GIS map display at three critical spatial levels, which are: a) across the whole sports field (Figure 3); b) www.sportsturfonline.com