INFLUENCE OF SAND TOPDRESSING ON THATCH DECOMPOSITION OF TWO BERMUDAGRASS SPECIES

摘要

relied on sand-topdressing and/or mechanical removal.Mechanical removal of thatch through vertical mowing and aerification is effective but disruptive to playing surfaces compared to sand topdressing.As a result,many turf managers have opted to implement sand-topdressing regiments as their primary method for reducing thatch buildup.This research was conducted to 1) determine the effect of cultivar on thatch decomposition and 2) examine the effect of sand topdressing on thatch microenvironment and decomposition.Sand topdressing treatments consisting of sterilized or non-sterilized sand applied at 0.4 cm 14 d-1 or as a single application at 2.4 cm to one hybrid bermudagrass,‘Tifway’ [Cynodon dactylon (L.) Pers.× C.transvaalensis Burtt-Davy] and one interspecific hybrid ‘Celebration’ (Cynodon dactylon L.Pers.) in 2008 and 2009.At the initiation of the experiment,Celebration had twice the thatch layer of Tifway.The only treatment that reduced thatch was sand applied every 14 d-1 reduced thatch 21% to 34% and 20% to 30% for Tifway and Celebration,respectively.In contrast,a single sand topdressing application and controls did not decrease thatch of either bermudagrass cultivar.Routine sand applications increased thatch relative humidity (RH) compared to controls.Laboratory experiments examining the effect of temperature,20 C and 30 C,and RH (80%,90%,95%,>99%) on Tifway and Celebration thatch decomposition showed increasing temperature and RH resulted in 189% to 397% greater microbial degradation.Failure to provide adequate moisture reduced microbial activity and led to declines of 170% to 243% decomposition when thatch was subjected to cyclic drying.Because thatch tissue composition and response to changes in temperature and RH were similar between cultivars,newer more vigorous bermudagrass cultivars such as Celebration may require more frequent sand topdressing regimens in conjunction with mechanical removal for acceptable thatch control.