Documenting Changes in USGA Specification Rootzone Properties in Ultradrawrf Bermudagrass Greens

The United States Golf Association Green Section has specifications for putting green construction to provide uniform playability and performance throughout the golfing season, however, it is recognized that chemical and physical rootzone properties of these greens change over time. To monitor and characterize these changes, thatch, organic matter (OM) accumulation, and saturated hydraulic conductivity (Ksat) of two ultradwarf bermudagrass (Cynodon dactylon x C. transvaalensis) greens on four south Florida (USA) golf courses (i.e., eight greens total) were measured over an eight-year period from 2006 through 2013. Over time, thatch thickness stabilized at 2.5 cm or less, whereas the OM stained layer increased in thickness to nearly 10 cm. The OM content fluctuated during the year in response to summer cultivation programs (i.e., verticutting and hollow-core aerification), but typically OM content was greater in spring than in fall. The Ksat typically was lower in spring and higher in fall, which could be attributed to summer cultivation practices and OM content. Golf course superintendents who routinely monitor thatch, OM, and Ksat on their ultradrawf bermudagrass USGA-specification sand-based greens potentially can use that information to illustrate to their stakeholders why summer cultivations are necessary, and what has been achieved from a summer cultivation program.