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5/1/2018
1
Athletic Field Performance Testing
Gerald Henry, PhD
University of Georgia
Chase Straw, PhD
University of Minnesota
Grass vs. artificial turf: Battle heats up for Women’s World Cup – The Post and Courier
Turf war: Artificial surfaces, grass both have pluses, minuses for football – Decatur Daily
The field that the Super Bowl will be played on in 4 months is a disaster – Business Insider
Dolphins blame field conditions, cleats for poor footing vs. Ravens – The Score
Patriots replacing new turf at Gillette Stadium after embarrassing loss to Chiefs – CBS Sports
Falcons, Rams battle slick grass at Coliseum in wild‐card game ‐ ESPN• The media does not understand turfgrass (or synthetic turf) nor its management
• Dramatize, embellish, aggrandize, amplify, hyperbolize…….
• We need to educate coaches, players, administration, the media, and the public
NFC Wild Card GameJanuary 6, 2018
Sports Field Management
• Athletic fields often blamed first for poor athletic performances
• Monetary inputs for field management are insufficient and usually an afterthought
Artificial Turf vs. Natural Grass Sports Fields
• Neither are management free
• Both exhibit field variability
• Injuries occur on either surface
• Focus needs to be on player safety and field playability
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Concussion Report Highlights Field Maintenance – New York Times
• 15.5% of concussions in high school sports occur when heads hit the playing surface
• Synthetic Turf• Concussion Legacy Foundation
• No difference between real and synthetic turf injury numbers
Variability
• A big challenge to understanding field conditions• Occurs when a measured quantity is different across and between locations
Soil Moisture
Spatial Relationships
Case Study: Oconee County H.S., GA
‐ 120 samples‐ Soil moisture (VWC)‐ Soil compaction (PR)‐ Turf quality (NDVI)‐ Surface hardness (G‐max)‐ Thatch depth‐ Root mass
‐ 0‐2 inch depth‐ 2‐5 inch depth
Soil moisture represents the irrigation pattern
VWC
Comp
Hard
NDVI
Thatch
Roots (upper)
Roots (lower)
Roots (total)
‐0.71
Spatial Variability
VWC (%)PR
(lbs. force)
Soil Moisture Soil Compaction
Variability
• Occurs regardless of field age, construction, sport, level, etc.
• Plant and soil parameters have major influences on each other
• Variability cannot be controlled, but management options need to account for it
• Need to gather info about your site!
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Disregarding Variability
Effects playability, performance, and predictability of your field
Performance Testing
• Used to evaluate field playability• Linked to player safety
• Can identify field variability• Soil compaction
• Soil moisture
• Surface hardness• Surface evenness• Sod strength• Root mass/depth
Player Safety
• You will never prevent all field‐related injuries
• Do your best to produce a uniform, “predictable” playing surface
•DUE DILIGENCE
Performance Testing Challenges
• What to test for?• Sensor technology and limitations
• How many samples do you take?• Accurately describe field variability
• How does your irrigation system impact data collection?• Effect of soil moisture on soil and plant parameters• Increasing irrigation efficiency
• When and how often do you sample?
• What do you do with the information?
Sensor Technology
Types of Sensors
• GPS – Elevation/Sample location
• TDR Probe – Soil moisture
• Penetrometer – Soil compaction
• Clegg Impact Tester – Surface hardness
• Shear Vane – Shear strength• Electrical Conductivity Soil Meter – Soil salinity, soil texture
• NDVI – Turfgrass vigor/health• Infrared Thermometer – Canopy temperature
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Soil Moisture Meter
• TDR Probe
• Measures soil moisture from a depth of 1.5 to 8 inches
• Recorded as % volumetric water content (%VWC)
• GPS compatible
Soil Compaction
• Penetrometer
• Determines soil compaction (to a depth of 18 inches) and potential water infiltration
• Recorded in pounds per square inch (PSI)
Surface Hardness
• Clegg Impact Tester
• Determines surface hardness in the upper 2 inches of the soil profile
• Recorded in gravities (G‐max)
Shear Strength
• Shear Vane• Measures rotational strength of the turfgrass (Nm)
• Influences the ability of athletes to grip the turf and make cuts
Plant Health/Turf Color
• NDVI Chlorophyll Meter
• Readings are reported on a scale of –1 to 1
• The NDVI value is a measure of leaf area index and green biomass
• Color Meter
• Readings reported as turf color on a scale of 1 to 9
Mobile Sensor Technology
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• Strong correlations for soil moisture and NDVI
• Moderate correlation for soil compaction• Mobile sensors insert penetrometer rods at a uniform speed = more accuracy
Historical Testing Procedures
5
4
3
2
1
Testing Natural Turf Sports Surfaces: The Value of Performance Quality Standards
Bartlett et al., 2009
5
6
7
8
9 104
3
2
1
ASTM F1936 – Test Procedure
10 Clegg Readings – Surface Hardness
5
6
7
8
9 104
3
2
1
Testing Procedures
? ?
?
? ?
?
• Issues:• Sample locations (≤ 12)• Assumes diamond shaped wear
• Descriptive stats determine variability
ASTM F1936 – Test Procedure60
110 70
80
50
120
80
50 120
110
Clegg Readings – Surface Hardness Avg: 85
Limit = 100 Gmax
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How many samples are needed to accurately depict
field performance?
450 Samples 115 Samples 36 Samples
Accuracy of Sample Size
Straw et al. 2017 – J. of Testing and Evaluation
450 SamplesMean = 22.9
VWC (%)
115 SamplesMean = 22.7
36 SamplesMean = 21.5
Accuracy of Sample Size
Soil Moisture
Influence of Soil Moisture on Data Collection
Irrigation System Efficiency
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Malfunctioning Irrigation Head
Improving the efficiency of your irrigation system
Current Approach ‐ Catch Can Method
• Assessment usually based on a small number of samples
• Measures distribution uniformity
• No indication of “effective” irrigation
Catch Can Method
Fate of Irrigation
Mass Flow vs. Preferential Flow
Uniformity vs. Efficiency
• The use of a soil moisture meter following irrigation application will provide more valuable information
• Water infiltration location• Rewetting potential• Soil compaction/thatch issues• Need for wetting agent applications
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Soil Moisture vs. Catch Can Soil Moisture vs. Catch Can
VWC (%) ml
= Irrigation head
VWC
Comp
Hard
NDVI
Thatch
Roots (upper)
Roots (lower)
Roots (total)
ID of Easily Correctable Problems
When a problem head is identified, field investigation is conducted to determine:
• Incorrect scheduling
• Localized dry spot
• Head alignment
• Head not operating
• Head spacing
• Wrong nozzle size
• Sprinkler or nozzle wear
• Mismatched sprinklers or nozzles
Influence of sampling time on data collection
Dry Down Following Irrigation Events
‐ 5 day soil dry down
‐ 120 samples‐ Soil moisture (VWC)‐ Soil compaction (PR)‐ Turf quality (NDVI)‐ Surface hardness (Gmax)‐ Traction
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Volumetric Water Content
%
lbs. force
Penetration Resistance
Normalized Difference
Vegetative Index
Day 1 Day 3 Day 5
Spatiotemporal Variability
‐ 34% + 25% + 3%
Gmax
Surface Hardness
Nm
Shear Strength
Day 1 Day 5
Spatiotemporal Variability
+ 15 % ‐ 12 %
Low Tech Mapping
Low‐Tech Mapping?
• What if I can’t afford this technology?
• What if I’m not comfortable using this technology?
• MAPS ARE NOT REQUIRED (although they provide the most detail):
• Low‐Tech Mapping = eyes + turf background + pencil & paper
• Google Earth – photos can be outdated!!
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Athletic Field Maps
• Mowing patterns
• Cultivation practices
• Pest presence• Wind direction
• Irrigation leaks
• Drainage issues
Information Application
• The more you know about your site the better decisions you can make
• Athletic field maps can help plan:• Irrigation Scheduling/Syringing
• Wetting Agent Applications
• Pesticide Applications
• PGR Applications
• Aerification Practices
• Drainage Installation
• Field Rotations
What do you do with the information?
Precision Turfgrass Management
• Applying inputs (water, cultivation, etc.) only where needed, when needed, and in the amount needed
• Fosters more precise and efficient application of inputs
PTM Examples
Soil Compaction SSMUs
Low
Moderate
High
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Site‐Specific Cultivation Study
Rep 1
Rep 2
Rep 3
Rep 4
Treatment plot
1. Control2. 1x entire plot3. 1x site‐specific4. 3x entire plot5. 3x site‐specific
Upper quartile map:
Top 25 % surface hardness of this plot:
Bottom 75% surface hardness of this plot:
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Spring 2015 Spring 2016
Site Specific Cultivation New Sprayer Technology
Smithco Star Command‐ Capstan SharpShooter‐ Raven Envizio GPS Pro
Star Command System
• On/off spraying function controlled at nozzle tip• Any application rate from 0.4 gal/1000 ft2
• Operating speed from 2 to 10 mph
• Proper flow and pressure is maintained
• No overspray
• Records/Maps of applications
Soil Moisture SSMUs
Low
Moderate
High
Weed Control
Spray Zones
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Estimated ET
Drone Technology Questions?
Dr. Gerald HenryE‐mail: [email protected]
@UGATurfgrass
Dr. Chase StrawE‐mail: [email protected]