Considerations with determining optimum soil depth for soil moisture and salinity measurement on golf course putting greens

Abstract Turfgrass ecosystems, soils, and rootzones are dynamic and unique to each golf course, sports pitch, and lawn. Portable hand‐held environmental monitoring instruments are commonly employed by practitioners; however, it is not clearly understood as to the ideal location within the soil profile to monitor and measure water and salinity. Soil samples were collected from 30 golf course sand‐based putting greens during May–September in 2005–2020, representing cool‐ and warm‐season turfgrasses in nine countries in North America, Europe, and Asia. At each site, 24 soil cores 1.9‐cm diameter × 18‐cm depth were randomly extracted, resulting in 12 soil cores partitioned into 3‐cm segments at 0‐ to 18‐cm depth (i.e., 0–3, 3–6, 6–9, 9–12, 12–15, and 15–18 cm), and 12 soil cores separated into 6 cm (i.e., 0–6, 6–12, and 12–18 cm). All soil samples were subjected to laboratory analysis to determine soil moisture saturation index (percent saturated water loss upon drying) and salinity (electrical conductivity of saturated soil‐paste extract [ECe] and electrical conductivity of soil pore water [ECw]). Analysis of soil data confirmed soil moisture and salinity were not uniformly distributed throughout the rootzone from the 0‐ to 18‐cm depth, and the majority of soil moisture and salinity were measured and observed within the upper layers at the 0‐ to 6‐cm depth. Therefore, the analysis of soil samples from golf course putting green sand‐based rootzones indicates an optimal placement for monitoring the highest concentrations of water (determined by the soil moisture saturation index) and salinity (determined by ECe and ECw) was 6 cm (i.e., the 0‐ to 6‐cm depth). When using soil moisture and salinity meters, turfgrass practitioners should monitor putting green rootzones at the upper 0‐ to 6‐cm depth.