• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.282-289
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• 2014

BACKGROUND: Methane($CH_4$) is considered as the secondmost potent greenhouse gas after carbon dioxide ($CO_2$). Methanogenesis is an enzyme-mediated multi-step process by methanogens. In the penultimate step, methylated Co-M is reduced by methyl Co-M reductase (MCR) to $CH_4$ involving a nickel-containing cofactor F430. The activity of MCR enzyme is dependent on the F430 and therefore, the bioavailability of Ni to methanogens is expected to influence MCR activity and $CH_4$ production in soil. In this study, different doses of EDTA(Ethylene Diamine Tetraacetic Acid) were applied in flooded soils to evaluate their suppression effect on methane production by chelating Ni of methanogenesis cofactor. METHODS AND RESULTS: EDTA was selected as chelating agents and added into wetland and rice paddy soil at the rates of 0, 25, 50, 75, and $100mmol\;kg^{-1}$ before 4-weeks incubation test. During the incubation, cumulative $CH_4$ production patterns were characterized. At the end of the experiment, soil samples were removed from their jars to analyze total soil Ni and water-soluble Ni content and methanogen abundance. Methane production from 100 mmol application decreased by 55 and 78% in both soils compared to that from 0 mmol. With increasing application rate of EDTA in both soils, water-soluble Ni concentration significantly increased, but total soil Ni and methanogen activities showed negative relationship during incubation test. CONCLUSION: The decrease in methane production with EDTA application was caused by chelating Ni of coenzyme F430 and inhibiting methanogenesis by methyl coenzyme M reductase. Consequently, EDTA application decreased uptake of Ni into methanogen, subsequently inhibited methanogen activities and reduced methane production in flooded soils.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.5
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• pp.395-404
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• 2017

Cultivating soybeans in rice paddy field reduces labor costs and increases the yield. Soybeans, however, are highly susceptible to excessive soil water in paddy field. Controlled drainage system can adjust groundwater level (GWL) and control soil moisture content, resulting in improvement soil environments for optimum crop growth. The objective of this study was to fit the soybean growth data (canopy height and stem diameter) using Gompertz model and Logistic model at different GWL and validate those models. The soybean, Daewon cultivar, was grown on the lysimeters controlled GWL (20cm and 40cm). The soil textures were silt loam and sandy loam. The canopy height and stem diameter were measured from the 20th days after seeding until harvest. The Gompertz and Logistic models were fitted with the growth data and each growth rate and maximum growth value was estimated. At the canopy height, the $R_2$ and RMSE were 0.99 and 1.58 in Gompertz model and 0.99 and 1.33 in Logistic model, respectively. The large discrepancy was shown in full maturity stage (R8), where plants have shed substantial amount of leaves. Regardless of soil texture, the maximum growth values at 40cm GWL were greater than the value at 20cm GWL. The growth rates were larger at silt loam. At the stem diameter, the $R_2$ and RMSE were 0.96 and 0.27 in Gompertz model and 0.96 and 0.26 in Logistic model, respectively. Unlike the canopy height, the stem diameter in R8 stage didn't decrease significantly. At both GWLs, the maximum growth values and the growth rates at silt loam were all larger than the values at sandy loam. In conclusion, Gompertz model and Logistic model both well fit the canopy heights and stem diameters of soybeans. These growth models can provide invaluable information for the development of precision water management system.

• Korean journal of food and cookery science
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• v.29 no.4
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• pp.343-351
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• 2013

To help reduce the 'breakfast-skip' rate of the high school students and improve such 'breakfast-skipping' practice this study devised a new covenience menu for school breakfast Program. Dictated by a dietitian the form of cooking was rendered within directly-cookable convenient food; The price of menu ranged from 1,500-2,000won taking into account the parents' survey ; the menu formation drew largely from the student food preference survey and their favorites. The composition of menu - the Korean dish and the western dish put together-were of two folds and was based on the two: main menu, subsidiary menu. While main menu used rice, the subsidiary one used fruits, salads, milk, and juices. Energy intake sufficiency standard was set at a level of between 1/4 and 1/3 of the relevent group(mid&high students, 15-18 yrs old)'s approximated energy need, drawn from the Dietary Reference Intakes For Koreans(2010). 10 disparate, divised menus were tested deliberately- cooked at a site, thereafter qualifed and supplemented to meet the targeted energy amount. The nuturitional facts of each menu set were measured through the usage of CAN-PRO 3.0, Computer Aided Nutritional Analysis Program, for professionals. Completed menu set were then given in photograph. The results of this study were as follows : The results of this study were as follows : the newly developed menu's calories and nuturitional content were as follows in the ratio of Dietary Reference Intakes For Koreans(2010) : Calories 95.7%(4.3% below the targeted intake standard), Protein(131.1%), Calcium(130.2%) the both of which marked higher than the recommended daily intake, iron(71.0%), Potassium(93.1%) both of which figure lower than the recommended daily intake. The cost of ingredients per each person was 1,335won, which was lower than the targeted cost(1500won). When calculated, hypothetically provided breakfast's labor hour needed per 1 meal is shown to be average 1.2 minute. In conslusion : Convenience style school breakfast program would bring an increse in the intake of high school students' breakfast, which may contribute not only to the sound physical growth but to academic performance. Various developments of the school breakfast program is much needed continually.

• Journal of Animal Environmental Science
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• v.14 no.2
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• pp.81-90
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• 2008

This study was carried out to investigate the effects of the organic feed on weight gain, feed conversion rate, and carcass characteristics of Hanwoo steers. Three feeding treatments(T1 : rice straw and commercial concentrates, T2 : organic hay and concentrates, T3 : organic corn silage and concentrates) for 22 months (from 6 to 28 months) were used. As a result, weight gain was not significantly different among treatments throughout this study. Also T1 tended to improve weight gain and daily weight gain without significance. The percentage of meat quality grade over the first grads ($1,\;1^+,\;1^{++}$) were 50% in the carcass of Hanwoo steers fed T1 and T2, and 70% fed T3, respectively. T2 and T3 tended to improve marbling score and oleic acid content.

• Korean Journal of Weed Science
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• v.4 no.1
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• pp.62-68
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• 1984

This experiment was conducted to find out the possibility for reducing herbicidal dose of the recommended herbicides in combining with the plant growth regulator "chlorflurenol" at the Yeongnam Crop Experiment Station, from 1981 to 1982. Chlorflurenol itself exhibited weed suppression effect against Monochoria raginalis Presl., Rotala indica Koehne, Cyperus difformis L., Lindernia procrembens Philcox, etc. and its effect increased as the concentrations of chlorflurenol increased from 100 to 1,000 ㎖/㏊. Combination of chlorflurenol with butachlor or thiobencarb, showing synergistic effect, reduced their recommended herbicidal rates by 50 to 75%, showing 90% of weed control rate, stic but combined treatment between chlorflurenol and bentazon showed an antagonistic effect since bentazon had poor control ability to Echinochloa crusgalli Beauv. An application of chlorflurenol showed no significant effect on rice growth, in terms of dry weight, but it resulted in the decrease in the ratio of leaf blade to other non-photosynthetic organ.

• Korean Journal of Microbiology
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• v.35 no.4
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• pp.289-295
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• 1999

Halotolerant microalga Dunaliella bardawil was reported to massively accumulate the ${\beta}$-carotene, which protects cells from excess light intensity. Maximum specific growth rate of 0.168/hr was achieved when cells were cultivated at 1 N NaCl, pH 8.0, light intensity 80 ${\mu}E/m^{2}/s$, agitation 70rpm. For the effectiv accumulation of ${\beta}$-carotene, ozone ro hydrogen peroxide was added to media which was irradiated with white fuorescent lamps with moderate light intensity of 250 ${\mu}E/m^{2}/s$. As a result, maximum volumetric content of ${\beta}$-carotene was 324 ${\mu}$g/㎖. The ${\beta}$-carotene extraction efficiency of vegetable oils was in the order of olive oil, sesame oil, rice brain oil, corn oil, and soy bean oil. Sonication and warming was effective in ${\mu}$-carotene extraction and finally 96.9% of ${\beta}$ could be extracted using olive oil.

• Applied Biological Chemistry
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• v.24 no.4
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• pp.230-237
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• 1981

For the investigation of efficient use of fertilizer nitrogen NPK simple trials were carried out using newly bred Tongil line(japonica indica hybrid selection) and the leading local varieties with sulfur coated area in fields for two years. The yield of Tongil line was higher than that of leading local varieties by 16% in the cool year and 23% is warm year with high solar radiation from NPK simple trials including SCU and 2-split application which were carried in 130 fields at 32 locations. Warm year increased yield by 9% in Tongil but only 3% in the local than the cool year did. Optimum nitrogen level was higher in Tongil by 3.8㎏ in the cool year and 5.5㎏ in warm year than for the local. Yearly variation of optimum nitrogen in the carne variety was greater than varietal variation in the same Year. Two-split application resulted in 1 to 2% of inconsistent yield variation. Sulfur coated urea increased yield by average 2 to 4% even at 20% reduced rate of nitrogen. It was remarkably effective in same $(27{\sim}39%)$, virgin (20%) and unmatured (10%) soils.

• The Korean Journal of Pesticide Science
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• v.14 no.4
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• pp.394-400
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• 2010

Insecticidal activities of methanol extracts of the different parts of Prunus mume were investigated against the larvae of Cnaphalocrocis medinalis (C. medinalis) by topical application. The mortalities of the larvae of C. medinalis were 34% at the concentration of 4,000 ppm, 36% of 8,000 ppm, 40% of 16,000 ppm and 58% of 32,000 ppm of the extracts from the fruits, and 38% of 4,000 ppm, 45% of 8,000 ppm, 58% of 16,000 ppm and 75% of 32,000 ppm from the stem + flower of Prunus mume (P. mume), respectively. The rates of pupation of C. medinalis treated with either fruit or stem+flower were gradually low according to the concentration of extracts increased. The weight of pupae of C. medinalis has no significantly different in between the control and the treated groups of the extracts from both of fruit and stem+flower. However, the differences of the pupal weight and the rate of pupation of C. medinalis treated with the extracts from the stem+flower and fruit of P. mume were significant as the level of 56% ($R^2$=0.56363, P=0.4364). Both of stem+flower and fruit extracts of P. mume showed good effects of anti-feeding against C. medinalis. The extracts of the stem+flower of P. mume could be advocated for developing as birational agent for the control of C. medinalis.

• Korean Journal of Soil Science and Fertilizer
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• v.5 no.1
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• pp.33-39
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• 1972

For the increase of productivity, canopy structure and nutritional status in various productivity grades (high>700, medium>600 and low>500kg/l0a as head rice) were investigated in a study using Jinheung(Oryza sativa L.) for the increase of producticity with following results: 1. High yield plot showed greater leaf area and slow decrease of it after heading stage. While low yield plot had rapidly decrease of leaf area. 2. High yield plot showed higher light transmission ratio (LTR) durnig early grow stage, low LTR. during late grow stage, and higher leaf area per LTR. 3. Net assimilation ratio was decrease with the increase of leaf area index (LAI) and it was always higher in high yield plot. 4. High yield plant had greater amount of total nitrogen uptake, slow uptake rate, and considerable uptake after heading while low yield plant showed higher uptake of nitrogen in early stage of growth and no uptake after heading. 5. The percent ratio starch at heading to total at harvesting was 40% for low yield plant and 10% for highyield plant inderting that high yield depends much on past-heading starch synthesis. 6. Main factor determining secondary yield was ripened grain ratio.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.955-960
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• 2012

In most agricultural soils, ammonium ($NH_4{^+}$) from fertilizer is quickly converted to nitrate ($NO_3{^-}$) by the process of nitrification which is crucial to the efficiency of N fertilizers and their impact on the environment. The salinity significantly affects efficiency of N fertilizer in reclaimed tidal soil, and the soil pH may influence the conversion rate of ammonium to nitrate and ultimately affect nitrogen losses from the soil profile. Several results suggest that pH has important effects on recovery of fall-applied N in the spring if field conditions are favorable for leaching and denitrification except that effects of soil pH are not serious under unfavorable conditions for N loss by these mechanisms. Soil pH, therefore, deserves attention as an important factor in the newly reclaimed tidal soils with applying N. However, fate of N studies in a newly reclaimed tidal soils have been rarely studied, especially under the conditions of saline-sodic and high pH. Therefore, understanding the fate of nitrogen species transformed from urea treated into the reclaimed tidal soil is important for nutrient management and environmental quality. In this article, we reviewed yields of rice and fate of nitrogen with respect to the properties of reclaimed tidal soils.