Managing isolated dry spot by topdressing inorganic amendments on a sloped golf green

Research putting greens are generally constructed with a flat surface, whereas putting greens on golf courses are less uniform and often have sloped, undulating surfaces. The grass on these sloped surfaces may be subject to localized dry spots and other problems related to the slope. The objective of this study was to evaluate the effectiveness of inorganic soil amendments in controlling localized dry spots on a sloped research green (SRG). The SRG contained an 8% slope facing north, a knoll (< 5% slope), and a 10% slope facing south. The green was seeded with 'Crenshaw' creeping bentgrass (Agrostis stolonifera L.). The topdressing treatments included 80% sand and 20% (v/v) peat, porous ceramic clay (PCC), calcined diatomaceous earth (CDE), zeolite clinoptilolite, and zeolite clinoptilolite preloaded with fertilizers (ZPF). Turf color and coverage were evaluated for two growing seasons. Evaluations were made during the growing seasons and before and after two cycles of dry-down treatments on the green. During most of the first growing season, ZPF-treated grass exhibited higher color and coverage ratings. This advantage was lost during the irrigated recovery period that followed the two periods of water stress. It is possible that the additional nitrogen applied with the ZPF improved turf quality during most of the summer but also predisposed the grass to more drought injury as evidenced by the lower quality ratings during the water stress period. Soil analysis demonstrated that the ZPF contained some sodium that may have reduced turf quality during stress periods. The application of inorganic amendments to the sloped plots was not observed to affect the development of localized dry spots during the two years of the study.