Chase M. Straw

Spatiotemporal variation of site-specific management units on natural turfgrass sports fields during dry down

Site-specific management units (SSMUs) are fundamental for the implementation of Precision Turfgrass Management. Short-term spatiotemporal variations of soil compaction and turfgrass vigor may be dynamic during a dry down period on natural turfgrass sports fields. This is due to the inverse relationship between soil compaction and soil moisture/drought stress, which may impact SSMU delineation and identification of site-specific deficient areas within a field. The spatiotemporal change of soil moisture, soil compaction, and turfgrass vigor SSMUs [as measured by volumetric water content (VWC), penetration resistance, and normalized difference vegetative index (NDVI)] were evaluated three times during a dry down from rainfall on native soil and sand capped natural turfgrass sports fields. The relationship of penetration resistance and NDVI with VWC was strongest and only significant on the native soil field during the dry down period. In general, as the fields dried, the magnitude of VWC SSMUs and NDVI SSMUs decreased, while the magnitude of penetration resistance SSMUs increased. This phenomenon was more drastic on the native soil field. Significant changes in spatial distributions were observed for VWC SSMUs and penetration resistance SSMUs on the native soil field; however, minimal changes were reported on the sand capped field. The spatial distributions of NDVI SSMUs were minimal on both fields. It is concluded that short-term spatiotemporal variations of SSMUs on sports fields during a dry down can be significant and considerations should be made prior to sampling based on the objective.

Does variability within natural turfgrass sports fields influence ground-derived injuries?

Abstract Natural turfgrass sports fields exhibit within-field variations due to climatic conditions, field construction, field management, and foot traffic patterns from field usage. Variations within a field could influence the playing surface predictability and require athletes to make abrupt or frequent adjustments that lead to increased ground-derived injury occurrence. This study introduces a new methodology aimed at evaluating the potential relationship between within-field variations of turfgrass sports field properties and ground-derived athlete injuries. Collegiate Club Sport athletes self-reported ground-derived injuries over two years. Soil moisture, turfgrass quality, surface hardness, and turfgrass shear strength were quantified from their two home fields. Hot spot analysis identified significantly high (hot spots) and low (cold spots) values within the fields. Injury locations were compared to hot spot maps each month. Binomial proportion tests determined if there were differences between observed injury proportions and expected proportions. Twenty-three ground-derived injuries were reported overall. The observed injury proportions occurring in turfgrass quality cold spots [0.52 (95% CI 0.29–0.76)] and soil moisture hot spots [0.43 (95% CI 0.22–0.66)] was significantly higher than expected [0.20 (p < .001) and 0.21 (p < .05), respectively]. Most injuries in significant areas of turfgrass quality, soil moisture, and surface hardness were along edges of hot and cold spots. These results suggest a potential relationship between within-field variations and ground-derived injuries, particularly in transition areas between non-significant and significant high and low values. Future larger-scale studies can incorporate the reported methodology to validate this relationship and implement strategies that reduce ground-derived injuries.

Predicting spatial structure of soil physical and chemical properties of golf course fairways using an apparent electrical conductivity sensor

Soil apparent electrical conductivity (ECa) has been used to map spatial variability of soil properties in multiple cropping systems and may have applications in precision turfgrass management (PTM). The objective of this research was to determine whether ECa data could predict the spatial structure of soil properties relevant to turfgrass management. Research was conducted at the University of Georgia (UGA) and the Georgia Club (GC) golf courses in North GA during the summer of 2016. A mobile Veris Q1000 device was used to collect georeferenced ECa data from six golf course fairways (three per course). Soil samples were collected from each fairway using a georeferenced grid to determine clay content, soil pH, cation exchange capacity (CEC) and organic matter (OM). To understand the predictive relationship between ECa and soil properties, correlation coefficients and multiple linear regression models were generated for each fairway. Spatial maps were used to visually demonstrate these relationships. Though some relationships were observed between ECa and soil properties (primarily clay, soil pH and OM on the UGA course), measured parameters were insufficient to fully explain spatial variability in ECa. Findings from this study suggest that spatial variability of soil properties in turfgrass can be significant enough to warrant PTM. Though ECa may be used to partially predict clay content, CEC, OM and soil pH, additional research is required to better understand ECa variability and its applications for PTM. Future research exploring ECa for PTM should consider the roles of soil moisture, temporal variability and topography.

Control of Lesser Swinecress in Creeping Bentgrass Putting Greens

J. A. Hoyle, Postdoctoral Research Associate, C. M. Straw, Graduate Research Assistant, G. M. Henry, Associate Professor, Department of Crop and Soil Sciences, University of Georgia, Athens, GA 30602; T. Cooper, Graduate Research Assistant, L. L. Beck, Graduate Research Assistant, and A. J. Hephner, Graduate Research Assistant, Department of Plant and Soil Science, Texas Tech University, Lubbock, TX 79409