Organic Matter Accumulation in Bentgrass Greens: Temporal and Spatial Characterizations.

One of the biggest problems in turfgrass management on golf courses is the accumulation of excessive amounts of organic matter on creeping bentgrass (Agrostis palustris Huds.) putting greens. Detrimental effects of organic matter (OM) accumulation are particularly acute in the transition zone in the southeastern U.S. Despite the importance of OM accumulation and its relationship to bentgrass health, many basic aspects of the process are still unknown. In this study, we attempt to address temporal and spatial characteristics of organic matter accumulation that have not been described in detail up to this time, but are key issues for understanding the bentgrass putting green system. Samples collected from 50 golf courses aged from less than one to 39 years old allowed development of a chronosequence that describes the rate of OM accumulation over years. The study included depth profiles of OM accumulation in different parts of the root zone. The analyses indicated that organic matter accumulated much faster near the soil surface (0-2.54 cm) from that just below it (2.54 – 7.68 cm). Levels of 4 to 5% OM were reached within about five years, and levels tended to level off after 15 to 20 years. At lower depths, accumulation occurred much more slowly and increased linearly over time. At five years, levels were just over 1% and they were still below 3.5% in greens that were greater than 20 years old. The results have a number of implications for management of organic matter in the field. The sustained accumulation of organic matter at the soil surface suggests that it may be unrealistic to expect that organic matter can be controlled entirely, but it is essential to continually and intensively manage the surface horizon.