• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.230-235
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• 1999

To study the effects of an urease inhibitor, N-(n-butyl)-thiophosphoric triamide (NBPT), and a nitrification inhibitor, dicyandiamide (DCD), on nitrogen losses and nitrogen use efficiency, urea fertilizer with or without inhibitors and slowrelease fertilizer (synthetic thermoplastic resins coated urea) were applied to direct-seeded flooded rice fields in 1998. In the urea and the urea+DCD treatments, NH$_4$$^{+}$ -N concentrations reached 50 mg N L$^{-1}$ after application. Urea+NBPT and urea+ NBPT+DCD treatments maintained NH$_4$$^{+}$ -N concentrations below 10 mg N L$^{-1}$ in the floodwater, while the slow-release fertilizer application maintained the lowest concentration of NH$_4$$^{+}$ -N in floodwater. The ammonia losses of urea+NBPT and urea+NBPT+DCD treatments were lower than those of urea and urea+DCD treatments during the 30 days after fertilizer application. It was found that N loss due to ammonia volatilization was minimized in the treatments of NBPT with urea and the slow-release fertilizer. The volatile loss of urea+DCD treatment was not significantly different from that of urea surface application. It was found that NBPT delayed urea hydrolysis and then decreased losses due to ammonia volatilization. DCD, a nitrification inhibitor, had no significant effect on ammonia loss under flooded conditions. The slow-release fertilizer application reduced ammonia volatilization loss most effectively. As N0$_3$$^{[-10]}$ -N concentrations in the soil water indicated that leaching losses of N were negligible, DCD was not effective in inhibiting nitrification in the flooded soil. The amount of N in plants was especially low in the slow-release fertilizer treatment during the early growth stage for 15 days after fertilization. The amount of N in the rice plants, however, was higher in the slow-release fertilizer treatment than in other treatments at harvest. Grain yields in the treatments of slow-release fertilizer, urea+NBPT+ DCD and urea+NBPT were significantly higher than those in the treatments of urea and urea+DCD. NBPT treatment with urea and the slow-release fertilizer application were effective in both reducing nitrogen losses and increasing grain yield by improving N use efficiency in direct-seeded flooded rice field.field.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.6
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• pp.381-386
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• 2002

A field experiment was conducted to evaluate the effect of split-application of slow-release fertilizer on the tea plant. The yield of the 1st harvested tea leaves had increased 12% in the slow-release fertilizer(two time split manuring) compared with the traditional manuring(four time split manuring), but that of the slow-release fertilizer to one time split manuring had decreased $6{\pm}3%$. In case of the 1st harvested leave, the contents of chemical components related to quality such as total nitrogen, total amino acid, chlorophyll, vitamin C and theanine were somewhat higher in the leaves of slow-release fertilizer(two time split manuring) treatment than in the traditional manuring, but that of tannin was low. The one time split manuring of slow-release fertilizer had a contrary tendency with two time split manuring treatment. In scoring test, appearance and quality of green tea were more excellent in the two time split manuring compared with one time split manuring of slow-release fertilizer and with the traditional manuring (four time split manuring). Therefore, use of slow-release fertilizer increased yield and quality of tea leaves, and decreased loss of nitrogen, phosphate and potassium.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.4
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• pp.254-259
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• 2008

The aim of this study was to investigate the effects of slow-release nitrogen fertilizer (SRNF) on the growth of radish plants. Wastepaper was deinked by alkaline solution and SRNF was produced from fertilizer impregnated wastepaper, which applied to an experimental plot compared with a urea fertilized plot. The plant height and total chlorophyll content of the radishes were higher while they were treated with SRNF than with urea. Some agronomic and chemical components were also observed and significant differences between the two fertilizers were found. When the soil was treated with SRNF, the pH, organic matter and total nitrogen content were higher than in the soil which was treated with urea.

• Korean Journal of Medicinal Crop Science
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• v.11 no.3
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• pp.190-194
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• 2003

A field experiment was conducted to evaluate effect by split-application of slow-release fertilizer on the tea plant. The yield of the 2nd harvested tea leaves was not different to the slow-release fertilizer of two time split manuring had been doing Sep. or Mar. compared with the traditional manuring had been doing four time split manuring, but that of the slow-release fertilizer to one time split manuring in Sep. had decreased $12.5{\pm}1.5%$. In case of the 2nd harvested leave, the contents of chemical components related to quality such as total nitrogen, total amino acid were somewhat higher in the slow-release fertilizer (two time split manuring) than in the traditional manuring, but those of tannin, and caffeine were low, and those of chlorophyll, vitamin C, free sugar and theanine were not different to out of treatments. In scoring test, appearance and quality of green tea were more excellence in the two time split manuring compared with one time split manuring of slow-release fertilizer and with the traditional manuring (four time split manuring). Therefore, I thought that use of slow-release fertilizer be increased yield and quality of tea leaves, and improved efficiency nature of nitrogen, phosphate and potassium out of soil fertilizer components.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.5
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• pp.269-273
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• 2005

A field experiment was conducted to evaluate the effect of slow-release fertilizer on the yield and quality of the third-harvest tea leaves. The yield of the third harvested tea leaves was decreased to 5.8-14.4% in slow-release fertilizer block, except to the N $50kg\;10a^{-1}$ ($316kg\;10a^{-1}$), compared to traditional urea treatment ($313kg\;10a^{-1}$). Nitrogen uptake and nitrogen uptake efficiency of slow-release fertilizer was reduced as nitrogen application level increased. The contents of chemical components related to the tea quality such as total-nitrogen, total amino acid, chlorophyll and theanine were somewhat lower in the slow-release fertilizer treatments, except to the treatment of N $50kg\;10a^{-1}$, than those in the traditional urea application, but those of tannin, caffeine and vitamin C were not different among the treatments. In scoring test, apparence and quality of green tea of the slow-release fertility treatments were not different, except to the N $40kg\;10a^{-1}$ treatment, compared to those in the treatment of urea. In conclusion, slow-release fertilizer and conventional urea treatments showed not different in both yield and quality of green tea.

• Food Science and Preservation
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• v.5 no.2
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• pp.127-132
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• 1998

In order to fad out an efficient way of topdressing nitrogen fertilizer in mulch-cropping system of onion(Allium cepa L.), solid, slow-release, and liquid forms of nitrogen fertilizers were allied to cv. 'Changnyungdaego' various number of times at different time, with 5 topdress applications of solid fertilizer serving as a control. Whole basal application of conventional solid fertilizer and 2 slow-release fertilizers were labor-saving and showed improved storage quality of bulbs, but resulted in poor plant growth and considerably low yield due to fertilizer shortage from early April. This suggests that topdress application is necessary. Liquid form of nitrogen fertilizer was more effective for plant growth and yield and saving labor than the solid form. Early applications was effective for increasing yield and storage quality of onion bulbs harvested. Thus two applications of liquid form of nitrogen fertilizer in February and March at rome month interval are recommended in mulch crowing system of onion.

• Asian Journal of Turfgrass Science
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• v.21 no.2
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• pp.177-182
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• 2007

When a football field is constructed using sand medium, the fertilizer management has to be adjusted because of the low nutrient holding capacity and higher leaching rate. The objective of this study was to test the effects of slow release fertilizers on Kentucky bluegrass (Poa pratensis L.) growth in simulated sport field rootzones with PVC pipe pots. Data of turfgrass color, uniformity, growth rate, biomass above ground, and the nitrate content in the leaching solution was collected at different growing stages and during four simulated rain fall periods. The result showed that the nutrient release rate of urea was the highest and that of controlled release nitrogen fertilizer was the lowest. Effects of the controlled release nitrogen fertilizer lasted 14 days more than other lawn fertilizers and 28 days longer than regular urea with acceptable quality levels of turf. The slow release fertilizer also restrained excessive growth of the grass, reduced the times of mowing. Slow release fertilizer used in this study reduced $NO_3$-N leaching by almost 50% at the beginning of turf establishment.

• Horticultural Science & Technology
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• v.19 no.4
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• pp.471-475
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• 2001

This experiment was conducted to evaluate the effect of slow-release fertilizer on warm type garlic cultivation in the Southwestern region of Korea. The slow-release fertilizers used were UF(Urea-Formaldehydes)70, 100, 130, CDU(Crotonylidene Diurea)100, and IBDU(Isobuty- lidene Diurea)100. The slow-release fertilizer treatment slightly increased plant height, leaf sheath diameter, and leaf number compare with conventional fertilizer treatment. Also, large bulb rate, nitrogen and pyruvic acid contents of garlic in slow-release fertilizer plot were higher than other treatments. Application of slow-release fertilizer increased the commercial yields.

• Korean Journal of Organic Agriculture
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• v.5 no.1
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• pp.79-85
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• 1996

This experiment was carried out to investigate the effect of slow-release fertilizers on yield of radigh. Fertilizers were treated with CDU, MEISTER, Jobi Gohyungbok-hapbiryo, Kyungki Wonyebokbi 1ho, Kyungkibokbi Nojeok, Kyungki Jeonjakgo-hyungbokbi, Tradidtional manuring, and No maunring. Yields of radish were increased with slow-release fertilizers, CDU and MEISTER were effective to radish shoot, also. But analysis of chemical components of plants and soil were no difference. It was very effect to increase yields of radish, to reduce in number of supplementary manuring and laboring.

• Korean Journal of Organic Agriculture
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• v.5 no.2
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• pp.85-91
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• 1997

This experiment was carried out to investigate the effect of slow-release fertilizers on yield of lettuce. Fertilizers were treated with CDU, MEISTER, Jobi Gohyungbokhapbiryo, Kyungki Wonyebokbi 1ho, Kyungkibokbi Nojeok, Kyungki Jeonjakgohyungbokbi, Traditional manuring, and No manuring. Yields of Spinach was increased with slow-release fertilizers, also. But analysis of chemical components of plants and soil were no difference. It was very effect to increase yields of lettuce, to reduce in number of supplementary manuring and laboring.