Soil moisture monitoring in amenity turfgrass ecosystems

Turfgrass management, in recent years has been influenced by the use of sensor technology designed to help assess conditions that impact turfgrass performance, particularly moisture content. However, an understanding of how best to use this technology is needed. As turfgrass systems are highly variable, one common characteristic is that their rootzone systems are not uniform and have variable performance characteristics at various depths and in various regions. An understanding of where in the rootzone the dominant water holding capacity resides as well as salinity concentrations would help prompt the positioning of sensor technology to best measure key variables, such as moisture content to allow for best decisions to be made with irrigation and other practices. A thorough lab analysis of sixty (60) rootzones at depths from 0 to 18 cm in 3 cm and 6 cm segments revealed that the dominant region of water retention and salinity concentration occurred in the 0 to 6 cm region thus confirming that rootzones, regardless of soil type, turf type or root depth, had a consistent characteristic that this upper region was similar throughout turfgrass systems in this regard. Using a fairly new (to turf) technology called the POGO TurfPro system (introduced in 2014), Coaxial Impedance Dielectric Permittivity technology, requiring no calibration allowed for consistent measurements to be made in turfgrass which further allowed analysis to occur to assess conditions and how to manipulate them. In a study of the use of this technology since 2014, use has significantly increased, particularly in the recent most years through the pandemic until present. In an analysis of various sampling density across a turfgrass plot, it was determined through analysis of the standard error of the mean that 3 to 4 samples for every 93 m2 (1000 ft2) of low cut turfgrass is necessary to assess the variability of that turf system across the entire plot. Indications show that as the height of cut rises, the density of sampling may lessen, but to understand the true conditions of turf across an entire plat of turf (putting green, fairway, sports field), one must take a minimum representative sampling. In a subsequent study looking at the measurements of moisture content, ball speed, and firmness during a professional golf tournament over a 4 day period, data showed that moisture influenced firmness and ball speed, but ball speed did not show significant influence from firmness alone. This relationship between moisture and these performance factors opens up questioning as to what else may be influencing conditions as the general feelings in the industry that drier conditions, for instance lead to faster ball speeds was not the case in this measured analysis. This set of studies indicates that effective and targeted monitoring with appropriate sensor technology allows insight to the underlying conditions that impact surface performance of turfgrass that otherwise would go unnoticed until a symptom occurred, indicating that the cause of that symptom has already occurred. Further, the ability to drive moisture lower is possible directly from measuring moisture content and further analyzing the conditions that occur as a result. This can have a significant impact on the turfgrass industry and reducing water use worldwide by understanding the optimal water level and the practices needed to maintain it over time without waste.