• Asian Journal of Turfgrass Science
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• v.11 no.2
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• pp.97-104
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• 1997

The objective of this study was to observe the differences in growth of creeping bentgrass turf to 'polymer coated urea fertilizer' and 'uncoated urea fertilizer', and to analyze durability of fertilizer effect with the 'polymer coated urea'. The experiment was initiated on June 3, 1996, at the Iowa State University Horticulture Research Station, north of Ames, Iowa. The experiment was conducted on an area of 'Penneagle' Creeping bentgrass(Agrostis palustris) maintained at fair-'way mowing height (1.3cm). The study was repeated at the same arrangement beginning on July 25, 1996. Visual quality data, clipping fresh and dry weight, and nitrogen(N) content in the clippings were taken weekly. Quality of the turf increased with increasing N rate. While quality ratings were higher for turf receiving polymer coated urea than for turf receiving uncoated urea at several times following treatment, but not significant. Fresh and dry clipping weights were quite variable during the trial. Visual quality rating and clipping yields improved with increasing rates of N but these differences were not statically significant between polymer coated and uncoated urea treatment. The durability of fertilizer efficiency in polymer coated urea was not last longer compare with uncoated urea from two weeks after treatment. Higher rates of N application increased the concentration of N in tissue but no significant differences between turf plots receiving polymer coated and uncoated urea. Key words: Polymer coated urea, Creeping bentgrass, Fertilizer, Turfgrass.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.3
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• pp.143-146
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• 2002

This study was undertaken to learn what ratio of clipping top was the most optimum for minimizing of the decrease of root yield of over 50g in sweetpotato at early cultivation. The test variety was "Shinyulmi" which was transplanted for early cultivation on April 18. The ratios of cripping top were 5, 10, 15, 20, and 25 percents. The date of clipping top was June 20 when the shoots were transplanted for double cropping. The total length of vine, the number of branches per plant, the number of tuberous roots over 50g and average root weight over 50g were not affected by clipping top. The ratio of root yield over 50g was lower over 20 percents of clipping top. The fresh weights per plant of top and bottom were similar as compared control with 15 percents of clipping top. In conclusion, the optimum ratio of clipping top was 15 percents for maximizing of the production of the shoots in sweetpotato for double cropping. cropping.

• Asian Journal of Turfgrass Science
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• v.15 no.4
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• pp.169-179
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• 2001

This study was conducted to determine the effect of root zone cooling on growth and quality of turfgrasses including Kentucky bluegrass (Poa pratensis L.‘Nuglade’), perennial ryegrass (Lolium perenne L.‘Accent’), tall fescue (Festuca arundinacea Schreb.‘Pixie’), and Japanese lawngrass (Zoysia japonica Steud.) in simulated athletic field during summer season in Korea. Mineral contents in clippings of turfgrasses grown at different soil mixtures and temperatures were also analyzed. Root zone cooling (approximately 4~6$^{\circ}C$ lower than that of untreated-control) resulted in good uniformity, little disease incidence and higher level of chlorophyll contents in cool-season turfgrasses. The effectiveness of root zone cooling in protecting disease incidence from high temperature stress was the most manifest in perennial ryegrass compared to others. Fresh clipping weight in treatment of root zone cooling was increased approximately 2 times in Kentucky bluegrass and perennial ryegrass, and 2.5 times in tall fescue compared to those of control. There was higher growth rate in a soil mixture composed of 80% peat moss ＋10% sand ＋10% soil (v/v/v) than in that of 80% pea moss ＋20% sand (v/v), Mineral contents of N, P, K, Ca, and Mg in clippings of three species of cool-season turfgrasses were significantly increased in treat-ment of root zone cooling but this was not found in Japanese lawngrass. Results showed that root zone cooling has a benefit in keeping good quality and growth of cool-season turfgrasses in sports field under supraoptimal ambient temperature during summer season.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.4
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• pp.373-381
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• 1994

This experiment was conducted to investigate the effects of nitrogen fertilizer level on forage yield and feed value, and to clarify the optimum nitrogen fertilizer level of rye in middle west area when cultured in paddy field. The field experiment treated 5 levels of nitrogen fertilization was carried out at Yesan from Oct. 1990 to June 1991. The fresh and dry weight increased with increased nitrogen fertilizer level by 30kg /10a, but dry matter ratio decreased. The ratio of leaf blade and leaf sheath in rye plant increased with increased nitrogen fertilizer level, but the ratio of stem and inflorescence decreased. The content and yield per unit area for protein, total digestible nutrient(TDN). Minerals, and energy increased with increased nitrogen fertilizer level, while acid detergent fiber(ADF) and neutral detergent fiber(NDF) decreased. The ratio of available protein among crude protein became higher with increased nitrogen fertilizer level. The optimum clipping time for net energy gain(NEG) and net energy maintenance(NEM) were 10 days earlier than milk stage for conventional items including TDN and proteins.

• Korean Journal of Agricultural Science
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• v.19 no.1
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• pp.16-27
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• 1992

To determine a potential of new sludge fertilizer for horticultural crops, comparative studies between commercial fertilizers (Jandibiryo and Wonyebokbi) and sludge fertilizer (Sludgebiryo) were made through examining the growth responses on zoysiagrass (Zoysia japponica Steud.) and several horticultural plants. 1. The pH of new sludge fertilizer remained near 6.5 regardless the particle size. The solubility of elements was highest in phosphorus, followed by nitrogen and potassium in the order. Especially, desorption of potassium was continued up to 48 hrs after solubilization. 2. There was an increase in shoot number per plant, length of stolon and rhizome, and root weight as well as clipping yield of zoysiagrass in the treatment of large size Sludgebiryo compared to small one and Jandibiryo. 3. Regardless the size of fertilizers, Sludgebiryo increased flower numbers in salvia (Salvia officinalis L. 'Hatzazz') compared to Wonyebokbi, although the difference was not great, However, leaf area and fresh weight of plant were more increased in Wonyebokbi application. 4. Flower diameter of marigold (Tagetes erecta L. 'Inca') was slightly increased in Sludgebiryo application, but the average number of lateral shoots and fresh weight per plant were significantly increased in the treatment of Wonyebokbi application. 5. Sludgebiryo effectively increased the length of both main and lateral shoots, number of flowers and weight of shoot in vinca (Vinca rosea L. 'Little Linde'), but root growth of plant was higher in Wonyebokbi application. 6, No differences between Wonyebokbi and Sludgebiryo were found in promoting the growth of leaves of perilla (Perilla frutescens Hara 'Yubsil' ), but chlorophyll content and seed weight were slightly higher in the application of Wonyebokbi compared to Sludgebiryo. In conclusion, the effectiveness of Sludgebiryo for horticultural plants was almost equal to commercial fertilizers such as Jandibiryo or Wonyebokbi. Expecially, Sludgebiryo appeared to effective on the growth of zoysiagrass, and the increase of flower size and numbers in flower crops. Results indicate that new-made Sludgebiryo can be recommended for turfgrass culture, and the flower crops in which quality depends on flower number and flower size.