Full TGIF Record # 19899
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Author(s):Bridges, Barry; Powell, A. J. Jr.
Title:Kentucky bluegrass thatch studies: III. Thatch-nitrogen study
Source:Kentucky Turfgrass Research. 1981, p. 31-32.
Publishing Information:Lexington, KY: University of Kentucky, College of Agriculture, Cooperative Extension Service
Keywords:TIC Keywords: Poa pratensis; Nitrogen fertilization; Fertilization rates; Fertilization timing; Thatch; pH; Thatch accumulation; Soil pH; Infiltration; Earthworms; Quality evaluation; Percent living ground cover
Abstract/Contents:Presents results of a March 1976 to May 1980 study to determine the effect of nitrogen rate and timing on pH, thatch accumulation, earthworm activity, water infiltration, and summer quality in a kenblue Kentucky bluegrass turf. Nitrogen rates varied between 0 and 5# N/1000 sq ft/yr as ammonium nitrate. Each application was made at 1# N/1000 sq ft and was also varied with respect to timing. Treatments received the nitrogen either in the spring, fall, or year-around. Differenes due to timing of nitrogen applications has been obscured by differences due to total nitrogen applied over the five-six year period. Total nitrogen applied ranged from 0-27 lbs N/1000 sq ft. Tables provide for each rate of nitrogen applied, pH of thatch and surface soil from March 1976 to May 1981, 5% green cover on 8/20/80, thatch thickness on 5/14/81, and earthworm population (#/m2) in spring and fall. pH was significantly reduced in the thatch and top two cm of soil by the increased nitrogen rates. However, there was no significant differences in the pH among treatments below the two cm level. Thatch accumulation was directly related to increasing nitrogen rates. An average of 0.75 cm more of thatch accumulated between the check and high nitrogen treatment. Earthworm activity was reduced significantly as nitrogen rates increased. The increased acidity as a result of the nitrification of ammonium nitrate caused either the death of migration of the earthworms out of the high nitrogen treatments. The reduced earthworm population was correlated with an increased accumulation of thatch. Water infiltration was determined for the treatments using double-ring infiltrometers. No consistent trends were found. The 1980 summer quality as measured by percent green cover was reduced up to 42% by the high nitrogen treatment. However, there was little difference between the check and treatments receiving one or two pounds of nitrogen per year. In 1981, there were no significant differences in color of turf. However % ground cover was significantly inferior in mid-October in plots receiving the highest rates (5# N/1000/yr) of Nitrogen. Additional work to be done include water infiltration studies, microbial counts, determination of root growth, and thatch-thickness measurements.
See Also:See also Part I: "Mechanical thatch study", p. 29-30, R=19889 R=19889

See also Part II: "Thatch-lime study", p. 30-32, R=19896 R=19896
ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
Bridges, B., and A. J. Jr. Powell. 1981. Kentucky bluegrass thatch studies: III. Thatch-nitrogen study. KY. Turfgrass Res. p. 31-32.
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MSU catalog number: SB 433 .A1 K4
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