Thatch Accumulation in Bermudagrass Turf in Relation to Management1

Abstract

AbstractThatch accumulation and decomposition in a ‘Tifgreen’ bermudagrass [Cynodon dactylon (L.) Pers.] putting green was studied in relation to fertility, fungicides, and clipping management. The effects of these practices were evaluated by measuring total thatch accumulation, lignin content of thatch, and soil microbial activity.Two sources of N, (NH4)2SO4 and activated sewage sludge (Milorganite), were applied at rates 0.25 and 0.75 kg/100 m2 every 2 weeks. Potassium was applied at two rates, 0 and 0.75 kg/100 m2, to each N treatment at 4‐week intervals. Fungicide treatments consisted of 0.18 kg/100 m2 of Manganese ethylene bisdithiocarbamate (Fore) and 0.12 kg/100 m2 of Tetramethythiuram disulfide (Tersan OM) applied alternately at 2‐week intervals. For the clipping management treatments, grass clippings were collected from some plots and left on others during each mowing.The high level of N increased thatch accumulation 30% and lignin content 15% and decreased microbial activity 6% as compared to the low level of N. The Milorganite treatments decreased thatch accumulation and lignin 12% and increased microbial activity 3% as compared to the (NH4)2SO4 treatments. Differences may largely explained by influence of N on growth rates. Application of K had no influence on any of the parameters measured. Fungicide treatments decreased thatch accumulation 16% and lignin content 20% and increased microbial activity 30%; these treatments may have inhibited plant growth. Clipping residue treatments increased lignin 7% and decreased microbial activity 7% as compared to a control. This study suggests that the use of a slow‐release N fertilizer applied at a level that maintains acceptable aesthetic turf quality may reduce thatch accumulation, whereas high rates of soluble N fertilizers accelerate thatch accumulation.