• Korean Journal of Organic Agriculture
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• v.23 no.4
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• pp.867-873
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• 2015

The potential of nitrogen mineralization was studied by applying organic fertilizer to soil and incubating at $25^{\circ}C$ for 28 weeks. The organic fertilizers used in this experiment were oil-cake (CF-I, CF-II) and amino acid fertilizer (AAF-I, AAF-II). Accumulated mineralized nitrogen (N) fits the frist-order kinetics during incubation. The N mineralization potential ($N_0$) for organic fertilizers treated soil was highest at AAF-II treatment with a value of 27.71 N mg/100g, then followed by CF-II, AAF-I, CF-I. The pure N mineralization potential ($N_0$ treatment - $N_0$ control) for CF-I, CF-II, AAF-I, AAF-II were 2.55, 5.83, 3.66, 8.57 N mg/100g, respectively. The amount of N mineralized from organic fertilizers applied soil ranged from 46% to 61% of the total N content in organic fertilizer. The half-life ($t_{1/2}$) of organic nitrogen in soil treated with oil-cake and amino acid fertilizer was 17-21 days. Therefore, half of nitrogen contained in oil-cake and amino acid fertilizer was mineralized after 3 weeks application.

• Korean Journal of Organic Agriculture
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• v.20 no.3
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• pp.357-368
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• 2012

This study was conducted to evaluate soil inorganic N concentrations and N uptake efficiency of sorghum ${\times}$ sudangrass hybrid (Sorghum bicolor (L.) Moench) as affected by organic nutrient sources from 2009 to 2011. The treatments included chemical fertilizer, compost, oilcake, alfalfa hay mulch, and control. Nutrient applications were made at rates equivalent to approximately 210 kg of actual N per hectare. The precipitation during the growth period from May to September was higher in 2011, followed by 2009, and 2010. Oilcake had the lowest C:N ratio in the raw materials. Compost treatment slowed N-mineralization rate in soil during the measured years. Soil mineral nutrition and dry matter production were not consistently affected by treatments, but the dry matter production was negatively correlated with the amount of precipitation from May to September for three years. Chemical fertilizer treatment increased N efficiency in plants in the first two years, observing with lower N efficiency in plants treated with compost for 3 years. Increased precipitation from June to August improved N efficiency in sudangrass plants treated with compost but reduced the efficiency with the chemical fertilizer. Total dry matter production and N efficiency in plants were not affected by the C:N ratio of the raw materials rather than weather condition.

• Korean Journal of Environmental Agriculture
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• v.20 no.1
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• pp.8-14
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• 2001

To investigate the effects of waste sludge from antibiotic fermentation on the growth of young radish and chemical properties of soil, five levels of fertilizer, control (recommended fertilizer, $N-P_2O_5-K_2O=160-59-104$ kg/ha), AS(control + sludge 1,000 kg/ha), AC(control + conventional compost 1,000 kg/ha), SNS(control - subtracting 30% N of sludge + sludge 1,000 kg/ha) and SNC(control - subtracting 30% N of conventional compost + conventional compost 1,000 kg/ha) were applied and radish was grown twice with same treatments on May and August in 1998. Germination rate and early growth of young radish grown with AS and SNS were lower than those grown in control and with AC, SNC. This negative effects by adding the sludge in the early growth seemed to be caused by damage of ammonia gas released during degradation of the sludge in soil. However, yield of young radish showed no significant difference among all the treatments including the AS and SNS at the 1st and 2nd experiment, and these suggested that the latter half of growth of young radish was accelerated by adding the sludge. Contents of T-N in young radish and inorganic N in soil showed a tendency to increase by adding the sludge while antibiotic substance, cephalosporin-C, was not detected in plant material and soils after harvest of young radish in both experiments. Consequently, waste sludge from antibiotic fermentation, which contains high levels of organic matter and nitrogen could be used as an useful resource in agriculture.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.4
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• pp.309-313
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• 1997

Field experiments were conducted on Jeonbug series (Fine silty, mesic family of Aeric Fluventic Haplaquepts), to study the effect of split application of N fertilizer in combination with rice straw on N use efficiency of dry-soil-direct seeded paddy rice. Treatments involved conventional application of N (in three splits; 40% at planting, 30% at five leaf stage and at heading stage) without rice straw, all basal application of N with straw application (5000 kg/ha), N application in two splits (70% at planting and 30% at heading stage) with rice straw application and N application in three splits (40% at planting, 30% at five leaf stage, 30% at heading stage) with application of rice straw. There was Zero N plot too for the estimation of N use efficiency. Seeding was done on dry soil and the filed was flooded 32 days after seeding. The fertilizer application rates were 160, 70, and 80 kg/ha of N, $P_2O_5$ and $K_2O$, respectively. The experiment was conducted for two years, in the same filed. The apparent use efficiency of fertilizer N by rice tended to be higher under the application of rice straw when N was applied in three splits. This, however, did not increase the yield of rice significantly. Even under the application of rice straw, the apparent N use efficiency was lower when N fertilizer was applied in one dose at the planting and in two splits. The lower N use efficiency in these cases, did not yield of rice significantly. The periodical analysis of mineral N in the soil suggested that higher mineral N in the soil at the early stages was responsible for the lower apparent N use efficiency.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.6
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• pp.479-485
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• 2002

This study was conducted in order to elucidate the effects of nitrogen level and split application method, and shading treatment during reproductive stage on sink formation. Japonica variety Choocheongbyeo and Hwaseongbyeo and indica$\times$japonica cross type variety Nampoongbyeo were used. Five levels (6 to 30 kg/10a at 6 kg/10a interval) of nitrogen fertilization, and two split application methods (50-25-25% and 30-30-40% as basaltillering-panicle fertilizer) for each nitrogen treatment were applied. In addition shading treatments (shading rate, 65%) were performed for N 12 kg/10a and 24 kg/10a plot. Shading were applied for 30 days from panicle initiation to heading, 15 days from panicle initiation and 15days before heading. Panicle per square meter, and primary rachis branches per panicle and differentiated number of secondary branch per panicle increased according as applied nitrogen amount increased up to 18 to 24 kg/10a, and there was no significant difference between two nitrogen application methods. Primary rachis branch and secondary branch per square meter also increased according as the amount of applied nitrogen increase up to 18 to 24 kg/10a, and there was no significant difference between nitrogen application methods. Panicle per square meter and primary rachis branch per panicle were significantly decreased due to shading treatments only in Choochengbyeo. In all varieties, shading reduced secondary rachis branch per panicle significantly and the reduction was greatest in 30 days shading during reproductive stage. Spikelets per square meter increased according as the amount of applied nitrogen increases up to 18 to 24kg/10a, but showed no move increase above this nitrogen application level. Significant difference was not shown between nitrogen split methods. Spikelets per square meter also decreased significantly due to shading treatment during reproductive stage, showing the greatest reduction by 30 days shading during reproductive stage, and the least by 15 days shading during booting stage. The variation of spikelets per square meter was influenced greatest by the variation of panicles per square meter and spikelets per secondary rachis branch.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.298-305
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• 2014

BACKGROUND: The utilization of green manures as alternatives to reduce the use of chemical fertilizers is considered a good agricultural practice. Effect of incorporation of green manure to soil on change of inorganic nitrogen (N) is well literatured. However, there have been few studies on examining entire dynamic of N including inorganic N and N gases in soil incorporated with green manure. The objective of this study was to examine the changes of inorganic N and N gases with single and mixture applications of hairy vetch and barley in the soil. METHODS AND RESULTS: Hairy vetch(H) and barley (B) were applied at the mixture ratio of B:H=0:0, B:H=100:0, B:H=0:100, and B:H=50:50 in soil. The soil-green manure mixtures were incubated in the dark at $25^{\circ}C$ for 17 weeks under aerobic conditions. Cumulative emission of $NH_3$ and $N_2O$ from soils amended with mixture of barley and hairy vetch(B:H=50:50) were less than those from amended with mono hairy vetch(B:H=0:100). Incorporation of single hairy vetch or mixture of barley and hair vetch application could significantly increased concentration of plant available N ($NH_4{^+}$) in early stage of plant growth and plant available N ($NO_3{^-}$) in later stage. However, high concentration of $NO_3{^-}$ in soil could cause adverse environmental impact through $NO_3{^-}$ leaching from soil. CONCLUSION: Conclusively, it might be a good soil management practice to incorporate mixture of barely and hairy vetch in the view point of increase in plant available N concentration and decrease in N losses through volatilization, denitrification, and leaching.

• Korean Journal of Materials Research
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• v.7 no.10
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• pp.832-837
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• 1997

본 연구에서는 반도체 소자의 수율을 현저히 저하시키는 반도체 습식 세정 시 건조 후 웨이퍼 표면에 형성된 water mark의생성 원인을 고찰하였다. 이를 위해 초순수수의 물방울을 다른 접촉각의 시편 위에 고의로 잔류시킨 후 질소 및 산소 분위기에서 건조시켰다. 건조 분위기와 상관없이 HF 처리된 소수성의시편 뿐만 아니라 친수성의 시편에서도 water mark이 관찰되었다. 생성된 water mark의 크기는 분위기에 무관하게 접촉각이 증가함에 따라 감소하였다. 그러나 산소 분위기에서 HF처리된 시편은 건조 후 질소 분위기에서 생성된 water mark의 크기보다 2배이상 크게 형성되었다. 이들 산소 및 질소 분위기에서 HF 처리된 실리콘 시편 위에 생성된 water mark의 성분을 AES(Auger Electron Spectroscopy)로 분석한 결과 water mark는 실리콘과 산소의 화합물 형태로 존재함을 확인하였다. AAS(Atomic Absorption Spectroscopy)분석 결과 건조 분위기에 상관 없이 HF처리된 실리콘 시편 위에 물방울을 30분 잔류시 물방울 내의 실리콘 농도가 증가하였다. 또한 물방울내 ozone을 첨가하여 실리콘 표면을 산화 시켰을 때 물방울과 표면의 접촉각 감소와 water mark의크기의 증가를 초래하였다.

• Journal of Life Science
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• v.12 no.5
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• pp.544-548
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• 2002

The object of this study was to investigate nitrogen fixation activity of rhizobium inoculated at seed coat when drought condition was applied in flowering period of soybean c.v. Samnamkong. The rhizobia used in this experiment were indigenous rhizobium, R2l4, RJl-29, USDA110 and USDA122. The experiment was done with 1/2000 Wagner pots in laboratory and greenhouse and was tested in completely randomized design with four replications. Nitrogen fixation activity in coventional culture was the highest in R2l4 and indigenous rhizobium among the five rhizobia strains. As given drought condition from flowering to maturity, nitrogen fixation activity was higher in R2l4 and RJl-29 than indigenous rhizobium. Leaf area and relative index (drought/convention) of pod weight were higher in USDA122, RJl-29 and R2l4 than indigenous rhizobium as given drought condition from flowering to maturity. High positive correlation was observed between nitrogen fixation activity of rhizobium and relative index(drought/convention) of pod weight. High negative correlation was observed between respiration of plant and relative index (drought/convention) of leaf area.

• Journal of Aquaculture
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• v.7 no.3
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• pp.177-187
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• 1994

The objective of the present study were to evaluate nitrification characteristics and determine optimum treatment conditions of three phase fluidized bed reactor for recycling water treatment of aquaculture. When the loading rates were 2.739-0.086kg $COD/m^3/day$ and 1.575-0.128kg $NH_4\;^+-N/m^3/day$, COD and ammonia removal efficiencies were $56.3-94.7\%\;and\; 67.3­92.6\%$, respectively. The maximum removal rates of COD and ammonia were 1200mg/l/day and 488mg/l/day, respectively. Ammonia removal rates were more than $90\%$ beyond 1hr HRT. The ammoniaremoval efficiency was sensitive to the variation of media concentration and air flowrate.

• KSBB Journal
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• v.15 no.1
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• pp.14-21
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• 2000

In this study, algae cultivation using the photobioreactor has been applied to remove the nitrogen and phosphorus compounds in the wastewater of the livestock industry. The optimal ratio of nitrate and ortho-phosphate concentration was found for the enhancement of removal efficiency. To achieve the high density culture of algae, the photobioreactor consisted of optical fibers wes developed to get the sufficient light intensity. The light could be illuminated uniformly from light source to the entire reactor by the optical fibers. The structured kinetic model was proposed to describe the growth rate, consumption rate of nitrates and ortho-phosphates in algae culture. The self-organizing fuzzy logic controller incorporated with genetic algorithm was constructed to control the semi-continuous wastewater treatment system. The proposed fuzzy logic controller was applied to maintain the nitrated concentration at the given set-point with the control of wastewater feeding rate. The experimental results showed that the self-organizing fuzzy logic controller could keep the nitrate concentration and enhance algae growth.