Research was conducted at Clemson University to address: what, if any, differences in efficacy exist between foliar and soil applied fertilizers. Under field conditions, various annual nitrogen rates with various ratios of liquid vs. granular products were evaluated on Agrostis palustris Huds. ‘L-93’ creeping bentgrass at the Clemson University Turfgrass Research Facility. Turf was mown six days per wk, and irrigated twice per wk to field capacity to assure a well-watered status.Two types of fertilizers were evaluated: 1) water soluble urea fertilizer 46-0-0 applied as a liquid, and 2) water soluble urea fertilizer 46-0-0 applied by hand. The granular and liquid fertilizers were applied every 14 days as 100:0, 50:50, and 0:100 ratios, at rates of 2 lbs N 1000 ft2-1 year-1 (77 kg ha-1 year-1), 4 lbs N 1000 ft2-1 year-1 (155 kg ha-1 year-1), 6 lbs N 1000 ft2-1 year-1 (233 kg ha-1 year-1), and 8 lbs N 1000 ft2-1 year-1 (310 kg ha-1 year-1) over 2 years. The liquid fertilizer was applied using a CO2 backpack sprayer with an output of 20 gal/A (187 L/ha), and the granules were shaken out uniformly over the turf by hand.
Visual quality based on turf color and density were rated on a scale from 0 (poor) to 9 (excellent), with 7 being minimum acceptable, every 14 days. Clippings from daily mowing were harvested monthly and analyzed for chlorophyll content, nutrient content and dry weight. Root samples were harvested with a 2 in (5 cm) diameter root harvester every 60 days to obtain root length density and root dry weight. Root sub-samples were collected twice per year to measure total nonstructural carbohydrates (TNC). TNC was measured by using Nelson’s Assay, which quantifies the reducing sugars in plants, glucose and fructose.
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