• Korean Journal of Soil Science and Fertilizer
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• v.13 no.1
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• pp.7-11
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• 1980

In order to learn about the volatilization of ammonia in relation to the amont of nitrogenous fertilizer, a laboratory experiment incubated between $35-40^{\circ}C$ for seven days, applying with 3.75mg N, 7.5mg N, and 11.25mg N in urea form, had been carried out. The result obtained are as follows : 1. As the amont of urea increases, the volatilization of ammonia enhanced. The enhancement of the volatilization of ammonia showed a close relationship with the pH raise of soil which is resulted from the formation of ammonia in soil. 2. Over liming decreased the volatilization of ammonia depressing the hydrolysis of urea and the ammonification of soil nitrogen. This tendency was far more pronounced when the pH of soil exceed 8.0.

• Journal of the Korean Society of Tobacco Science
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• v.5 no.1
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• pp.87-95
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• 1983

This study was conducted to evaluate the affect of soil conditioners and their application rates on the growth, Yield and quality of Flue-cured tobacco. Soil conditioners for this study were Montmorillonite arid Zeolite as clay mineral source and Rice hull and Sawdust as organic source. Their application rates were 500, 1000, 2000kg/10a. The growth of tobacco plants was promoted, compared with that of Non- treated plot (control) by Zeolite, Montmorillonite and Rice hull application but decreased by Sawdust application. During tobacco growing season soil moisture content, compared with control, was increased by Zeolite and Montmorillonite application but decreased by Rice hull and Sawdust application. In contrast to soil moisture content, soil temperature was higher in the Rice hull and Sawdust plot than in the plot of Zeolite and Montmorillonite. The treatment of Sawdust, compared with control, obviously accelerated the maturity of tobacco, increased reducing Sugar but decreased total alkaloids, nicotine and nitrogen content of cured leaves. The Sawdust Plot decreased the Yield (kg/10a) with significant difference by 1 %level but significantly increased leaf quality (Won/kg) and value (Won/10a) by 1%and 5 %level, respectively. The present application , ate of Nitrogen in Korea (12.5kg/10a) seems to be excessive for Flue-cured tobacco production.

• Journal of Plant Biology
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• v.7 no.2
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• pp.1-8
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• 1964

Cha, Jong Whan (Dept. of Biology, Graduate School, Dong Kuk Univ.) The changes of chemical properties of forest soils in dry and wet seasons. Kor. Jour. Bot. VII(2): 1-8, 1964. Soil selected for the present investigation was collected from a mountain of the Forestry Experiment Station of the vicinity of Seoul. The forest communities studied were three forest and a unplanted soils. The soil samples were obtained from each forest type during dry and wet seasons. And these samples were collected from four horizons of all communities respectively. It was showed that exchangeable hydrogen was increased by rainfall, and total exchangeable base decreased in the same way. The content of nitrogen is washed away by rainfall, especially ammonium nitrogen was highly significant between dry and wet season. On the contrary, organic matter and available phosphorus were of no significant difference between dry and wet seasons. The values of pH appeared a different response in dry and wet seasons according to the plant communities. The needle-leaved forest soils showed more acidity than the broad-leaved forest soils, and the least acidity in open places. All nutrients in soil studied gradually decreased down the profiles. According to statistical analyses of the soil components among all soil horizons, total exchangeable bases in wet season indicated only significant at 1%. Exchangeable hydrogen and organic matter of the soil in dry season was particularly very low with increased depth in the profile. The fertility level of most forested soils selected for the present investigation is low according to chemical tests for available nutrient elements.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.3
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• pp.84-93
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• 2010

This study was carried out to analyze the vegetation properties, soil characteristics and ordination of Leontice microrhyncha population in South Korea. The Leontice microrhyncha population was classified into Quercus mongolica dominant population, Morus bombycis dominant population, Fraxinus mandshurica population and Leontice microrhyncha typical dominant. The Leontice microrhyncha population was located at an elevation of 633m to 1,336m in Korea. In the study sites, soil organic matter, total nitrogen, available phosphate, exchangeable potassium, exchangeable calcium, exchangeable magnesium, cation exchange capacity and soil pH were 8.40~10.58%, 0.42~0.61%, 14.15~25.07mg/kg, 0.44~0.59cmol$^+$/kg, 2.35~6.33cmol$^+$/kg, 0.35~0.98cmol$^+$/kg, 26.04~33.48cmol$^+$/kg and 4.69~5.32 respectively. Morus bombycis dominant population was found in the low elevation and gentle sloped area that has high percentage of phosphoric acid and less percentage of total nitrogen, exchangeable calcium, exchangeable magnesium than other dominant population. Fraxinus mandshurica dominant population and Leontice microrhyncha typical population were found in the comparatively high elevation area that has low percentage of phosphoric acid and high percentage of total nitrogen, exchangeable calcium, exchangeable magnesium. Quercus mongolica dominant population was found in the medium elevation area that has medium percentage of total nitrogen, exchangeable calcium, exchangeable magnesium.

• Asian Journal of Turfgrass Science
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• v.3 no.1
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• pp.24-33
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• 1989

This study was conducted to investigate the effect of paclobutrazol [(2 RS , 3 RS )1-(4- chlor-ophenyl )-4, 4- dimethyl -2- (1, 2, 4- triazol -1- yl )- pentan -3-01] on the tolerance of hi-gh temperature and drought stress as related to growth retardation , iranspiration rate , soil water content , nitrogen level and photosynthetic rate in perennial ryegrass ( Loliurn perenne L . ' Omega H , ). Plants were given a 30 ml soil drench of paclohutrazol at the concentrations of 0, 0.01, 0.1, 1.0, 10.. 0, mg / 6 .5cm- diameter pot . The rcsults were as follows : 1. Increasing concentrations of paclohutrazul reduced plant height , leaf area , fresh weight and dry weight , hut increased chlorophyll content per unit area . The number of tillers and leaf width were not affected hy the paclobutrazol concentrations . 2. The proper concentration of paclohatrazol on growth retardation in perennial ryegrass was about I mq /pot , hut leaf deformity and severe growth retardation were shown at high concentration of 10 mq / pot . 3. Perennial ryegrasses grown at 30˚C were shown significantly short plant height and low leaf nitrogen level compared with those grown at 20˚C. Increasing concentrations of paclohutrazol at 20˚C increased nitrogen level hut it could not increase nitrogen level at 30˚C . 4. During the drought stress , increasing temperatures significantly promoted transpiration rate and wilting time . It took about 5 days at 20˚C and 3 days at 30˚C to reach wilting time of leaves from water stress treatment . Soil water contents at wilting time of non-treated controls were averaged 6. 871% at 20˚C and 6. 17% at 30˚C 5. Paclohutrazol reduced transpiration rate at high temperature and drought stress . Wilting appeared at the lower water content of soil according to increasing concentrations of paclobutrazol at 30˚C hut there were no differences among concentrations of at 20˚C. 6.Paclohutrazol treatment at 1 rag /pot reduced injury rate of leaves from 67.1 % and 100 % in control plants to 15.7% and 80% at 20˚C and 3010, respectively. 7. Photosynthetic rate per unit area was significantly reduced at high temperature . Paclohutrazol stimulated photosynthetic rate with increase of concentrations at 20˚C but there was no increasing effect at 30˚C.

• Journal of Microbiology and Biotechnology
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• v.20 no.3
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• pp.602-608
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• 2010

An atrazine-degrading bacterium, strain KU001, was obtained from a sugarcane field at the Cane and Sugar Research and Development Center at the Kasetsart University, Kamphaeng Saen Campus, Thailand. Strain KU001 had a rod-to-coccus morphological cycle during growth. Biolog carbon source analysis indicated that the isolated bacterium was Arthrobacter histidinolovorans. Sequence analysis of the PCR product indicated that the 16S rRNA gene in strain KU001 was 99% identical to the same region in Arthrobacter sp. The atrazine degradation pathway in strain KU001 consisted of the catabolic genes trzN, atzB, and atzC. Strain KU001 was able to use atrazine as a sole nitrogen source for growth, and surprisingly, atrazine degradation was not inhibited in cells grown on ammonium, nitrate, or urea, as compared with cells cultivated on growth-limiting nitrogen sources. During the atrazine degradation process, the supplementation of nitrate completely inhibited atrazine degradation activity in strain KU001, whereas ammonium and urea had no effect on atrazine degradation activity. The addition of strain KU001 to sterile or nonsterile soils resulted in the disappearance of atrazine at a rate that was 4- to 5-fold more than that achieved by the indigenous microbial community. The addition of citrate to soils resulted in enhanced atrazine degradation, where 80% of atrazine disappeared within one day following nutrient supplementation.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.2
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• pp.63-71
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• 2010

This study was carried out to analyze the vegetation and soil characteristic, and ordination between Calanthe discolor and C. sieboldii population, Jeju Island. The C. discolor population was classified into Cryptomeria japonica dominant population, Miscanthus sinensis dominant population, and C. discolor typical population. The C. discolor population was located in elevation of 156m to 430m, and C. sieboldii was located in elevation of 424m to 604m in Jeju Island. In the study sites, soil organic matter, nitrogen, exchangeable potassium, exchangeable calcium, exchangeable magnesium, cation exchange capacity, and soil pH were 30.05~53.58%, 0.74~1.64%, 0.80~1.95cmol$^+$/kg, 4.35~22.53cmol$^+$/kg, 4.00~6.63cmol$^+$/kg, 25.60~51.33cmol$^+$/kg, and 4.83~5.70, respectively. C. discolor population was found in the low elevation and steep sloped area that has less organic matter, total nitrogen, and cation exchange capacity than C. sieboldii population. C. discolor typical population was found in the high elevation area that has more organic matter and total nitrogen in the C. discolor. Miscanthus sinensis dominant population was found in the shade of west direction of japanese black pine. C. sieboldii was found in a high elevation and a gentle sloped area that has high percentage organic matter, total nitrogen, and cation exchange capacity.

• Korean Journal of Agricultural Science
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• v.49 no.4
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• pp.657-666
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• 2022

Nitrogen (N) is a vital element in growing crops and is essential for improving the yield and quality of crops. Thus, N fertilizer is the most widely used fertilizer and the primary N input source in soil-crop systems. Inorganic fertilizers such as urea are known to improve crop productivity and increase soil fertility. However, application with excessive amounts can interfere with crop growth and accelerate soil acidification. For these reasons, the use of organic fertilizers, which mainly contain organic nitrogen, has gradually increased worldwide. Therefore, this study evaluated the effects of N fertilizer on the growth of Chinese cabbage including its functional compounds glucosinolates (GSLs). For the cultivation of Chinse cabbage, inorganic fertilizer was used for urea, and organic fertilizers were divided into conventional and biochar-based fertilizers. The growth parameters of Chinese cabbage treated by organic fertilizers was better than those of the inorganic fertilizers. Additionally, it was found that their co-application was more efficient. However, their GSL contents were lower with the application of the organic fertilizers. The characteristics of the experimental soil also changed according to the type, amounts and co-application of fertilizers. Therefore, this study presents the basis for an eco-friendly method that can increase the functionality and productivity of Chinese cabbage compared to conventional cultivations.

• Korean Journal of Agricultural Science
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• v.48 no.4
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• pp.787-796
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• 2021

Nitrogen (N) is the most important element during the process of plant growth, and the quality of crops varies depending on the amount of nitrogen present. Most of the nitrogen is used for plant growth, but approximately 10 - 20% of Nitrogen is carried away by the wind in the form of NH₃. This volatilized NH₃ reacts with various oxides in the atmosphere to generate secondary particulate matter. To address this, the present study attempts to reduce NH₃ occurring in the soil using biochar at a specific pH. Biochar was used as a treatment with 1% (w·w^-1) of the soil, and urea was applied at different levels of 160, 320, and 640 kg·N·ha^-1. NH₃ generated in the soil was collected using a dynamic column and analyzed using the indophenol blue method. NH₃ showed the maximum emission within 4 - 7 days after the fertilizer treatment, decreasing sharply afterward. NH₃ emission levels were reduced with the biochar treatment in all cases. Among them, the best reduction efficiency was found to be approximately 25% for the 320 kg·ha^-1 + pH 6.7 biochar treatment. Consequently, in order to reduce the amount of NH₃ generated in the soil, it is most effective to use pH 6.7 biochar and a standard amount (320 kg·N·ha^-1) of urea.

• Korean Journal of Soil Science and Fertilizer
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• v.1 no.1
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• pp.61-71
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• 1968

1. In pot exreriments, the leaf blades of rice plants grown on Akiochi soil were weakened and the leaves dropped noticeably. This phenomenon could be prevented with application of silicate materials such as potassium silicate, Wallastonite and silicate slag (normally used silicate fertilizer in Korea). 2. Grain yield was increased by application of all the silicate materials. The effect of wollastonite was not lower than the effect of silicate slag. 3. Basal application of wollastonite gives a higher effect on the grain yield than top dressing. With higher wollastonite application, the nitrogen effect on the grain yield increases. This increase in nitrogen effect becomes more pronounced when the nitrogen level is higher. 4. Silica content in the plant waas increased by application of silicate materials to the soil. The increase in silica content in the plant was most noticeable with wollastonite. Basal application of wollastonite proved to be more effective than top dressing. Iron and nitrogen content in the plant decreased by application of the silicate materials. 5. The application of the silicate materials to Akiochi soil increases the resistance of rice to leaf blast, neck blast and Helminthosporium leaf spot. Among the silicate materials, wollastonite was most effective. 6. Damage by leaf blast increased proportionally with the nitrogen level, but decreased clearly with increase in wollastonite level. This phenomon was most pronounced for late transplanting time. 7. Damage by Helminthosporium leaf spot was also proportionally reduced by wollastonite application.