Pre-game field safety assessment: future implications of risk assessment

The primary goal of every sports turf manager is to produce a safe, uniform, playing surface to prevent injuries to athletes while being aesthetically pleasing to all involved. Due to high expectations regarding player safety by sports turf managers, players, and coaches, field assessments and safety checks need to be assessed and addressed in our cultural management practices before games so field conditions can be improved before game time.

The current STMA sports field safety and maintenance checklist visually evaluates the evenness and traction of the playing surface for natural grass. Evenness is impacted by overall turfgrass quality (uniformity, color, density, and rooting). Traction is critical to generating and controlling player speed and turning. Traction is impacted by turfgrass coverage and to some extent field drainage (relates to soil moisture). Poor traction, either a lack of turfgrass coverage or drainage (slickness), can lead to muscle pulls and a variety of other injuries. In addition to visual assessment, maintenance and safety checklists also need to assess agronomic properties such as soil compaction and surface hardness that occurs from repeated wear on natural grass. Surface hardness affects the player’s ability to turn sharply, and along with soil compaction, increases athlete injury due to falls and tackles to the ground. All of these factors are important in cultivating a healthy turfgrass system that is resistant to traffic and wear from sports. Of course, all of this needs to be assessed in a timely manner to be ready before the next game.

On the current checklist, communication between facilities and athletics is assessed because that relationship is critical in producing a safe playing field for athletes. The University of Minnesota Crookston athletic department asked for assistance from the turf management program in providing some management strategies for facilities to use to improve the overall turfgrass quality of the football field. U of M Crookston’s field differs from most collegiate fields in that a high school football team plays their home games on the field. During a scheduled turf science lab, the students preformed a visual assessment of overall turfgrass quality and coverage on the football field using the playing surface for natural grass section from the STMA checklist. In addition, they collected data on soil compaction using a FieldScout SC 900 meter and on soil moisture using a FieldScout TDR 300, both of which are hand-held devices that provide instant results. The football field was divided into 30 subplots where six readings were randomly taken per subplot. Those six readings were averaged to give a subplot mean per measurement. The percentage of subplots resulting in ≥ 300 psi for soil compaction (4” depth) was calculated for the field where <30% received a little to none compaction rating, 30-50% a slight compaction rating, 50-75% a moderate compaction rating, and >75% a severe compaction rating. Calculated results indicated that 50% of the football field was moderately compacted and that 100% of the center of the field (between hash marks) was severely compacted before game one. Eighty-six percent of the field was saturated (>40 % VWC for a silty clay loam soil). It was evident from the assessment that soil compaction below ground was directly affecting quality of above ground plant responses.

The students presented their findings to both athletics and facilities to gain the experience of working with both groups and to understand how important communication is between the two departments. Facilities was not able to immediately aerate the field, so we decided to do a semester long pilot study for the remaining home games. Soil compaction increased on the field until facilities was able to perform aerification (solid-tine) after game four, which decreased soil compaction to less than 10%. We recommended to facilities that they aerify every 2 weeks because less than a week later 53% of the field was moderately compacted. Soil moisture was saturated, >70% of the field, three of the four remaining games of the season. The recommendation to facilities was to reduce irrigation on the field and in the future use a wilt-base irrigation approach and be cognizant of the weather when irrigating.

After collaborating with the sport recreational management department and the athletic trainers, this project was redesigned in 2017 and 2018 to include player injury data to determine whether agronomic improvements identified in the pre-game assessment produced field conditions that reduced player injury. Further analysis will standardize injury incidents as a function of injury exposure (i.e., number of plays football players are on the field where they run the risk of getting injured) and compare that risk to the agronomic data.

Two additional measurements were added to the pre-game assessment, surface hardness and turfgrass color. A FieldScout TruFirm was used to determine the firmness of the playing surface to compare surface consistency and variability. Turfgrass color was determined using a FieldScout CM 1000 Chlorophyll meter. A second site was also added to the project, the newly renovated girls’ soccer field. At the end of the project, a survey was created to ascertain the perceptions of field and playing conditions from the coaches, trainers, and players. The football field was severely compacted before game one and game four, 77% and 90% respectively in 2017. Surface hardness on the field was 100% firm before game four (no data available for game 1). There were also two injuries reported after game two and five, where there were no issues with soil compaction or surface hardness.

For the soccer field, there was little to no soil compaction measured on the field (24 subplots plus goals). Surface firmness did reach 75% firm on the field before game five where two injuries were reported (shin splints). Both goal areas were severely firm before game five. There were many instances where injuries occurred but the field (football and soccer) was not compacted or hard. Since both the football and soccer field was saturated throughout the season this could have resulted in poor traction where the playing surface was slick causing injury to athletes. In 2018, there were games where weather conditions (snow cover) prevented data collection. The number of injuries that occurred during these games equals the number of injuries on all other games of the season. Weather, and how it affects field conditions, should be addressed in future revisions of the sports field safety and maintenance checklist as it relates to player injury.

At the end of the season players, coaches, and trainers were given access to the survey to determine their perceptions of the fields. Forty-nine athletes, three trainers, and four coaches completed the survey at the time of this publication. When asked if the athletes noticed an improvement in field conditions between 2017 and 2018, 8 responded yes, 17 responded no, and 24 had no basis for comparisons (freshman or transfer student athletes). When asked how the athletes perceived the playing conditions of the fields, 1 said good, 4 said average, and 44 said poor.

At the start of this project, we wanted to be able to quantify the relationship between the agronomic and risk assessments that will lead to strategies intended to improve turfgrass field conditions. We also wanted to be able to identify cultural management strategies that would be beneficial to sports turf managers by reducing the risk of player injuries. Soil cultivation practices, specifically aerification every two weeks, is important in reducing soil compaction and surface hardness on high traffic fields. Although soil and plant health for the existing turf improved through soil cultivation practices, the same emphasis needs to be placed on improving the above ground turf coverage and overall turf quality. Overseeding should be part of every management plan to fill in divots, holes, and ruts created by constant traffic immediately following play.

Communicating and highlighting the importance of these efforts made by sports turf managers to improve player safety goes a long way to changing the perceptions of all in involved. Kristina S. Walker, PhD, is associate professor of agronomy, University of Minnesota Crookston; Eddie Walker II, PhD, is an assistant professor of sport and recreational management in Crookston. References are available at