Full TGIF Record # 19781
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Publication Type:
Author(s):Bridges, Barry; Powell, A. J. Jr.
Title:Kentucky bluegrass thatch-nitrogen study
Source:Kentucky Turfgrass Research. 1982, p. 28-33.
Publishing Information:Lexington, KY: University of Kentucky, College of Agriculture, Cooperative Extension Service
Keywords:TIC Keywords: Poa pratensis; Nitrogen fertilization; Fertilization rates; Thatch; Liming; pH; Thatch control; Mechanical control; Thatch decomposition; Lawn turf; Earthworms; Vertical mowing; Topdressing; Grubs; Injuries; Root weight; Soil pH; Coring
Abstract/Contents:1982 study to : 1) determine the effects of multiple nitrogen (N) applications on certain soil and turf parameters related to thatch accumulation in Kenblue Kentucky bluegrass turf and 2) to evaluate the effectiveness of lime and certain mechanical treatments on the decomposition rate of accumulated thatch in a Kentucky bluegrass lawn. Tables provide results : 1) in the turf study on the effect of deep or Ryan Coring, verticutting, topdressing and liming on thatch reduction and thatch and soil pH. In the turf study, the highest N rate doubled thatch accumulation, reduced the earthworm population up to 88% and significantly reduced the micro-organism population. Increased acidity associated with the high rate of N was assumed to be the primary cause of the earthworm and microbial decline and the increase in thatch. Root mass was decreased a maximum of 70% in the highest N treatment. The reduction in roots and earthworms population was correlated to a 3-fold reduction in saturated water conductivity. Although severe white grub damage was measured only in the high N turf, no significant difference in grub populations were found. This research shows the importance of maintaining a favorable pH (above 5.0) for maximum earthworm and microbial activity - both of which are required for rapid thatch decomposition and water percolation. The research also stresses the importance of sampling the thatch and/or surface 1-2 cm of soil for determining lime requirements. Composite samples normally collected from the surface 0-12cm layer may not reveal acidity problems that may already be affecting the earthworm and micro-organism populations. In the lawn study, topdressing was more effective than vertical mowing or core aerification in reducing thatch, while finely ground dolomitic lime was more effective than coarse lime or finely ground fluid lime in raising pH of the thatch layer. It is evident from these studies that lime movement through thatch is extremely slow and coring coupled with lime is of little immediate benefit. Although topdressing with soil is of little practical use in home lawns, it was most beneficial in reducing thatch. Vertical mowing for 3 consecutive seasons was also a successful method for reducing thatch. Although coring was of little value in this short-term study, thatch decomposition would likely be increased with time due to improved conditions within the thatch as more soil is incorporated. It is assumed that coring would be more beneficial in lawn maintenance program in preventing thatch build-up rather than reducing an already accumulated thatch.
ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
Bridges, B., and A. J. Jr. Powell. 1982. Kentucky bluegrass thatch-nitrogen study. KY. Turfgrass Res. p. 28-33.
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