Date of Award

12-2006

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Plant and Environmental Science

Advisor

McCarty, Lambert B

Abstract

Limited turfgrass research comparing the efficiency of foliar to granular fertilizers exists. To expand upon previous research and to determine advantages and disadvantages between dry and liquid fertilizers applied to turf, research was conducted at Clemson University to compare the efficiency of three nitrogen (N) carriers (100% granular, 100% liquid, and 50% granular + 50% liquid) using N rates ranging from 98 to 390 kg ha-1 on growth and performance of creeping bentgrass and ultra-dwarf bermudagrass.

Studies were conducted in 2003 and 2004 to evaluate liquid and/or granular N fertilization on turfgrass quality, clipping yield, and root biomass of `L-93` creeping bentgrass [Agrostis palustris (Hud.)] and `TifEagle` bermudagrass [Cynodon dactylon (l.) x C. transvaalensis Burtt-Davy]. Treatments consisted of two annual nitrogen inputs, 127 and 190 kg ha-1 for bentgrass and 190 and 254 kg ha-1 for bermudagrass, using 100% granular urea fertilizer, 50% granular urea + 50% liquid urea fertilizer, or 100% liquid urea fertilizer. For `L-93` creeping bentgrass, the highest turfgrass quality ratings were achieved with the high N rate applied as 100% liquid urea. Differences in clipping yield were only observed during August each year. Clipping yield was greatest with 100% liquid in 2004, while, 100% granular produced greater clipping yield in 2005. Also, clipping yield was greater in 2005 for 100% granular treatment compared to 2004. In June, 100% liquid produced greater % clipping N compared to 50% liquid + 50% granular and 100% granular. However, the 100% granular treatment produced greater % clipping N in August compared to 100% liquid.

For `TifEagle` bermudagrass, turf quality was unacceptable (<7) for the months of June, July, and August. However, during June, July, and August, turf quality was significantly higher, 5.1, 6.5, and 5.4 respectively, at 254 kg N/ha, compared to 190 kg N/ha. Clipping yield was 42%, 41%, and 85% greater at 254 kg N/ha during June, July, and August, respectively, compared to 190 kg N/ha. In June, % clipping N was greatest, 23% and 18% respectively, with 100% liquid and 100% granular, compared to the 50% liquid + 50% granular.

Greenhouse and field experiments were conducted from 2004 through 2006 to compare the efficiency of three nitrogen (N) carriers (100% granular, 100% liquid, and 50% granular + 50% liquid) using N rates ranging from 98 to 390 kg ha-1 on growth and performance of creeping bentgrass. Under greenhouse conditions, all treatments provided acceptable turf quality (≥ 7), and no differences among treatments were detected for visual quality, root total N content, or root length. Clipping yield and percent clipping N were reduced when granular fertilizer was replaced with half or all liquid fertilizer. Chlorophyll content, percent clipping N, and clipping yield increased with increasing N rate. Root dry weight at 8-15 cm depth decreased as N rate increased.

Under field conditions, lowest N level provided unacceptable (< 7) visual quality throughout the two-year study. For summer, acceptable visual quality (> 7) was provided by 195 and 293 kg N ha-1, while visual quality for 390 kg N ha-1 was unacceptable (< 6.6). Clipping yield, total percent clipping N, and leaf chlorophyll content increased with increasing N rate. N rate adversely affected root length density (RLD) in July, while seasonal differences in root dry weight and specific root length (SRL) were observed. Also, SRL peaked with 50% granular + 50% liquid in November and January. Organic matter content increased up to 75% with the highest N rate. Root TNC content was adversely affected by N rate, and TNC content declined 10% from March to July. These results suggest a rate of 195 to 293 kg N ha-1 yr-1 as optimum for bentgrass growth in the transition zone of the U.S. Combining both liquid and granular methods appear superior compared to relying on one method exclusively.

Included in

Horticulture Commons

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