Golfdom, August 2010

variation in nitrate levels due to the UAN application an intense four week 28 day period soil sampling was performed during the 2008 growing season July 23 through Aug 16 2008 Soil samples were broken into 0 to 15 cm and 15 to 30 cm soil depths Leachate was collected three times after rainfall events from three separate fertigation cycles 28 days cycle once at four 13 and 26 days into cycle April 1 May 7 and Aug 12 respectively Leachate was analyzed for nitrate and nitrite being leached and compared to the EPA limits of 10 milligrams mg 1 and 1 mg 1 respectively A biomass collection and several visual quality ratings were performed throughout the 2008 growing season to analyze the health of the turfgrass Two and three way analysis of variance ANOVA were performed on the collected data using the Statistical Analysis Software general linear model GLM procedure at the 005 probability level with the Tukey multiple comparison test used to determine differences in means between the treatments There was no significant difference in fertigation frequency for any of the data collected therefore only the rate means are shown Soil analysis showed large amounts of nitrate nitrogen being retained in the soil and not being utilized by the turfgrass at rates of 488 and 977 kg N ha month During a natural rain event Aug 18 2008 resulting in 828 cm of precipitation this large buildup of nitrate nitrogen in the soil was leached causing excessive nitratenitrogen leachate over the EPA limits The first two water samples were taken early in the growing season when the applied nitrate nitrogen was not being effectively used by the turfgrass This led to higher nitrate nitrogen leachate values in the lower 122 and 244 kg N ha month rates which lowered significantly once the turfgrass was fully established Leaf tissue N levels were 13 percent 30 percent 34 percent 35 percent and 46 percent for the 0 12 24 49 and 98 kg N ha month rates respectively The control was significantly lower and the 98 kg N ha month rate significantly higher than the other rates However all four rates had leaf tissue nitrogen percentages between the 3 to 5 percent sufficiency range for a fairway turfgrass McCarty 2001 Visual quality ratings were highest for the 122 244 and 488 kg N ha month rates compared with the control and 977 kg N ha month rate data not shown Visual quality rating for both the 488 and 977 kg N ha month rates were often lower due to excessive vegetative growth that led to scalping with the weekly clipping Both these rates however did still produce an acceptable quality turfgrass When compared with the vegetative growth data it was generally seen that as vegetative growth increased visual quality increased as well However sometimes the quality of the turfgrass was affected if the growth was excessive This would show up during the weekly clipping when some of the more vigorous turfgrass would have a scalping effect when clipped Results from the study indicate a fertigation rate of 122 kg N ha month produced a quality turfgrass while minimizing nitratenitrogen leaching in sandy loam soil Optimum quality was obtained at the 244 and 488 kg N ha month rates This range is currently recommended for optimum bermudagrass quality and growth However in this study the 244 and 488 kg N ha month rates produced nitrate leachate levels that were well above EPA limits These rates may have produced such high nitrate leaching values due to the limited root zone and soil profile of only 30 cm If a deeper soil profile had been used leachate values may not have been as high Michael Maurer Ph D is an assistant professor of turfgrass science and horticulture at Stephen F Austin State University James Moken received his masters degree in environmental science from Stephen F Austin Leon Young Ph D is regents professor and director of the soil plant and water analysis lab at Stephen F Austin REFERENCES d Hulst M 2000 Getting to the root of the matter Landscape Contractor Magazine pgs 22 27 McCarty L B 2001 Best golf course management practices Prentice Hall Inc Upper Saddle River New Jersey Moore J 2009 Does this stuff work or not USGA Green Section Record May June 2009 14 16 Purpur J 2009 Watering from underground Golf Course Management July 2009 80 84 Ad Index Advertiser Page No Andersons CV4 B A S F 3 19 22 Bayer Environmental 23 25 27 29 Becker Underwood 31 Bell Labs 2 51 DuPont 13 FMC 7 17 57 Jacobsen CV3 NuFarm 14 15 Otterbine Barebo 54 PBI Gordon 10 Phoenix Environmental 9 Quali Pro 5 Rain Bird 11 SipcamAdvan 12 Sonic Solutions 50 Toro CV2 Turfco Mfg 26 30 Underhill 32 Insert White Metal Golf 2 Williams Williams Auctioneers 24 TURFGRASS TRENDS John Deere 58 This index is provided as an additional service The publisher does not assume any liability for errors or omissions GOLFDOM ISSN 1526 4270 is published monthly 12 issues per year by Questex Media Group LLC 306 W Michigan Street Suite 200 Duluth MN 55802 Corporate office 275 Grove 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