Comparison of Granular and Liquid Nitrogen Fertility on 'TifEagle' Bermudagrass

1. Comparison of Granular and Liquid Nitrogen Fertility on 'TifEagle' Bermudagrass F.W. Totten, H. Liu, L.B. McCarty, J. Toler, and C. Baldwin Basis Generally, turfgrasses are fertilized either: (1) through soil nutrition which targets root uptake; or (2) by liquid fertilization which targets foliar or root uptake. However, little information exists on efficiency of granular to liquid fertilizers among turfgrasses. As golf courses have shifted to predominantly liquid based fertilizer programs in the Southeast, subsequent poor cool-season grass performance during summer and fall months has been observed. Therefore, could the exclusive use of liquid fertilizers, or the limited use of granular fertilizers contribute to this poor performance?Such research could supply turf managers with knowledge needed to determine the effectiveness of these liquid products and their cost effectiveness. • Objective • Determine differences in efficacy between liquid and soil applied N fertilizer, • Observe responses (e.g., turf color, density, rooting, and tissue N content) to N fertilizer treatments. Materials and Methods Various rates and ratios of granular and liquid fertilization were used to compare turf quality, turfgrass clipping yield, and root biomass on a newly established ‘TifEagle' bermudagrass green constructed to USGA specifications from April to November 2003 and 2004. Treatments consisted of two annual nitrogen inputs, 190 and 254 kg/ha (3.9 and 5.2 lb N/1,000 ft-2) using 100% granular fertilizer, 50% granular + 50% liquid fertilizer, and 100% liquid fertilizer. Field plot size was 1.8m x 1.2m (6 ft x 4 ft). The study design was a randomized complete block with three replications. Foliar and granular applications were conducted biweekly from May to September. An 18-3-18 granular fertilizer was used, and liquid fertilizer applications were made using Daniels 10-3-5 and 5-0-7 products (Progressive Turf Inc, Atlanta, GA). Visual turf quality (color and density) was evaluated every 14 days from May to September using a scale 1 to 9, with 9 = excellent, 1= poor. A rating <6 was unacceptable. ‘TifEagle' clippings were harvested for dry weight and nutrient analysis monthly in June, July, August, and September. Tissue nutrient analysis was conducted by the Clemson University Soil Testing Laboratory. For the purpose of this presentation, only turfgrass quality, clipping yield, and clipping nutrient analysis will be reported. Results Turf Quality: Turf quality was significantly higher at 254 kg N/ha, compared to 190 kg N/ha during June, July , and August. Turf quality for both rates was acceptable (≥6) only in July. 100% granular form produced higher turf quality during the month of July, compared to other forms evaluated. ‘TifEagle’ clipping yield: As expected, clipping yield was significantly greater at 254 kg N/ha, compared to 190 kg N/ha during June, July, and August. N form had no effect on clipping yield. ‘TifEagle’ % N in clippings: % clipping N was greatest with 100% liquid and 100% granular forms, during the month of June, compared to the 50% liquid/50% granular form. Table 1. ‘TifEagle’ visual quality in response to fertilizer treatment. A Table 2. ‘TifEagle’ clipping yield in response to fertilizer treatment. Table 3. ‘TifEagle’ % clipping N in response to fertilizer treatment. • Future Research • Further evaluation of foliar vs. soil-applied fertilization in fine turf, • Detailed study of turfgrass leaf morphology to accurately determine the dynamics of turfgrass foliar absorption. • Acknowledgements • Many thanks to GCSAA, CGCSA, Milliken Turf Products, Progressive Turf LLC., for the funding of research, • Tim Ale, Brandon Haley, Steve Long, Raymond McCauley, Patrick McCullough, James Thackston, Greg Willis. Picture 1. 100% liquid at 254 kg N/ha (24-August-2003). Picture 2. 50% liquid/50% granular at 254 kg N/ha (24-August-2003). Picture 3. 100% granular at 254 kg N/ha (24-August-2003).