Creeping Bentgrass Establishment on Amended‐Sand Root Zones in Two Microenvironments

Abstract

Sand‐based root zones are commonly used for construction of golf course putting greens. Objectives of this field study were to (i) evaluate sand‐based root zone mixtures varying in amendment (fine loam, peat, and inorganic) on the establishment of ‘L‐93’ creeping bentgrass (Agrostis stolonifera L.), (ii) compare findings to related published studies, and (iii) repeat the trial in two locations varying in air circulation to assess microenvironmental effect. Eleven root zone mixtures, using predominantly medium‐sized sand as the majority component, were replicated four times in a randomized complete block design nested within the two microenvironments. Plots were seeded in May 1998 and establishment was assessed to June 1999. Mixtures with a capillary porosity (−3 kPa water potential) at the high end of, or slightly exceeding, the United States Golf Association (USGA) criterion range (0.15–0.25 m3 m−3) provided more rapid establishment and better turf performance, yet root mass was lowest in these mixtures. Thus, variation in water availability among mixtures appeared sufficient to affect distribution of dry matter between roots and shoots. Mixtures amended to provide greater nutrient retention improved turf establishment; however, low water retention in the inorganic mixtures negated this advantage longer term as irrigation and fertilization shifted from establishment toward a maintenance objective. While shoot response to microenvironment was more limited, total root mass 1 yr after seeding was 24% greater in the open microenvironment than the enclosed, indicating that the initial effect of enclosed microenvironments on growth may go unrecognized during grow‐in unless rooting is assessed.