• Korean Journal of Soil Science and Fertilizer
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• v.11 no.3
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• pp.127-144
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• 1979

Recent trend in the studies on the forming processes, chemical characteristics and chemical structure of humic substances with some discussions are reviewed and some arguments for the elucidation of the chemical structure of humic substances are summarized.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.6
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• pp.416-431
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• 2000

The objective of this study was to determine the effects of various kinds of composts on the change of soil chemical properties in upland soils. Field experiments were conducted in the loam and sandy loam soils. Various kinds of composts such as poultry manure compost(PMC), cow manure compost(CMC), human excrement sludge(HES), and food industrial sludge compost(FISC) were applied annually at rates of 0, 40, and $80Mg\;ha^{-1}$ to soils grown with soybean and maize plants for 4 years during 1994 to 1997. The results of this study were as follows : The continuous application of human excrement sludge decreased soil pH up to 4.4~5.0, while other compost treatments increased soil pH compared with control plot. The EC increased initially and showed their maximum values at 20days after compost application, and then decreased up to 40 days, thereafter kept a certain level. The available phosphorous accumulated at 0~20cm depth in loam soil, and 0~50cm in sandy loam soil. Annual accumulation rates were 17% higher in sandy loam soil than loam soil. The more compost application rates and times, the higher base saturation percentage increased in upland soils. Four year's application at a rate of $80Mg\;ha^{-1}$ per year increased the base saturation percentage to 87~97% compared with 45% at control plot in the loam soil. While in sandy loam soil only three year's application of same rate increased the base saturation percentage to 81~92% compared with 30.4% at control plot. The average annual increasing rate of base saturation percentage at the same application rates of composts were higher in sandy loam soil by 2.0~3.7 times than in loam soil. The application of compost increased the exchangeable Ca, Mg, and K contents of soils by 2, 2~3, and 3~5 times, respectively, compared with the control. The contents of exchangeable cations were high in surface soil, and decreased with increase of soil depths. In the case of heavy metal content, there were no difference at the application of PMC and CMC but Ni, Fe, Zn, Cu was increased a little when the HES applied, and Ni and Cr was increased application with FISC.

• 한국해양학회지
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• v.14 no.1
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• pp.15-25
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• 1979

A study on field bioassay test using four species of commercially important shellfish was carried out to assess the effect of pollutants and determine the extent of marine environmental pollution of the Masan Bay from 9 to 15 August 1978. Water quality analysis and planktological examination of sea water were made during the experiment and the examination gave the following results. The water temperature was so high at 31.7$^{\circ}C$ in maximum and rather subject to change on weather condition of the land than on the effect of the water mass from outer bay. The range of DO,COD and SS at the stations were 0.3-7.08cc/l, 0.07-3.31ppm and 5.5-117ppm, respectively with the high values of COD and SS at the stations 7 and 1. The concentrations of the dissolved inorganic nitrogen in sea water, NH$\sub$4/-N, NO$\sub$2/-N, NO$\sub$3/-N, and PO$\sub$4/-P were 18.90-99.80, 2.48- 19.60, 13.00-39.00 and 1.04-14.0$\mu\textrm{g}$ at/l, respectively with decrease of their values in the outer part of the Bay. The high values mentioned above were caused by the sewage and industrial activities. The effects of organic waste are increased oxygen demand, nutrient concentration, turbidity and a higher input of pathogens, leading to structural changes in the marine ecosystems and to a considerable hazard to public health. The percentage composition of phytoplankton standing crop between diatom and dinoflagellate was characterized by making a difference between the two groups in respect of location: a decrease of diatom and a increase of dinoflagellate in numerical abundance toward inner part from outer part of the bay. Namely phytoplankton organisms were composed of 80% of diatom and 20% of dinoflagellate in outer bay, on the contrary, only 4% of diatom and 96% of dinoflagellate occupied by 94% of prorocentrum micans known as tolerant species to polluted reaas in the inner bay. On the occurrence and composition of zooplankton, there are two significant communities in the bay:one is characterized by the predominance of Oithona nana and the other by Favella sp They were composed of a range from 84% to 90% of the total organisms and monotonously constituted of themselves only at most inner station 3 even small numbers. From the results mentioned above, Oithona nana, Favella and prorocentrum micans recommed themselves as valuable indicators for judging the extent of the marine pollution.During the period of the biossays Mytilus edulis showed the highest mortality and Tapes japonica the lowest one between the four test species. The highest death rate by stations was found at most inner stations 3'and 4near Masan Free Export Zone with the most sensitive response and the lowest one occured at outer station 13 where no death specimen of oyster and arkshell was found during the whole test period.As for mussel,85 percent death rate appeared after 72 hours and 100percent rate after 120hours at station 4. It was found that the significant high mortality of the test shellfish mentioned above was caused by severe pollution with mainly organic pollutants from domestic sewage and industrial wastes from the results of too much higher concentrations of dissolved inorganic nitrogen especially ammonia-N,COD,SS and lack of dissolved oxygen,and furthermore occurrence and abundance composition of Prorcentrum,Favella and Oithona nana by stations, valuable indicator species of coastal pollution by orgnic and boilogical pollutants.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.2
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• pp.125-131
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• 2005

This study investigated effects of acid deposition on cation contents of rinus densiflora needles. The results of the investigation were as follows: By regression the ion balance was shown to be 1.01 of slope and 0.973 of $R^2$. The volume weighted average pH measurements of wet deposition in Seoul from January to December, 2001, 2002 and 2003 were: pH 5.1, pH 5.0 and pH 4.8, respectively. The annual wet deposition ion amount was shown to gradually increase during this study period. Cation content of needles in the fall season was higher than during other seasons, but $Al^{3+}$ ion contents showed nodifferences among seasons. When ion concentrations of wet deposition were higher, cation contents of needles were generally lower.

• Journal of Animal Science and Technology
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• v.45 no.1
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• pp.41-48
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• 2003

Two experiments were conducted to investigate the effect of dietary supplementation of yeast culture on the performance of broiler chicks and noxious gas emission in broiler houses. Two hundred forty and three hundred and twenty, one day old Cobb male broiler chicks in Expt 1 and Expt 2, respectively were alloted to four treatment levels of yeast culture (0, 0.1, 0.2, 0.4%). To each treatment, 60 birds were assigned in Expt 1 and 5 replicates of 16 birds each were assigned in Expt 2. Basal diets contained 21.5% and 19.0% CP, and 3,100kcal/kg ME for the starting and finishing periods, respectively. Ammonia and $CO_2$ gas emission were detected twice a day for seven days during the five week period of Expt 1. Weight gain, feed intake and feed efficiency were measured for five weeks in Expt 2. Intestinal microbes, blood cholesterol and ND antibody titer were examined at the end of Expt 2. In Expt 1, the concentration of $NH_3$ in the house of birds fed yeast culture tended to be lower than the control. It was significantly lower in the 0.4% yeast culture treatment than the control (P<0.05). $CO_2$ concentration was significantly lower in all yeast culture treatments regardless of its dietary supplemental level than the control (P<0.05). different from others. Feed efficiency (feed/gain), however, was significantly improved in all yeast culture treatments relative to that of the control for starting period (P<0.05) and that of 0.2% yeast culture treatment was significantly lower than those of the control and 0.4% for the overall period. Total number of E. coli in the ileum of birds fed yeast culture at 0.1 and 0.2% was significantly lower than those of the control and 0.4% in the ileum. The CFU of Lactobacillus spp. of birds fed yeast culture at 0.1% was higher in the cecum compared to other treatments (P<0.05). Total cholesterol level of chicks fed 0.1% yeast culture seemed to be lower compared to that of other treatments, whereas LDL-cholesterol level was significantly lower than those of the control and 0.4% treatment. ND antibody titer tended to be higher in the yeast culture treatments than the control, but was not significantly different. The results of these experiments indicated that 0.2% yeast culture may have a potential to reduce the noxious gas emission in broiler houses and maximize the performance of broiler chicks.

• Korean Journal of Environmental Agriculture
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• v.19 no.1
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• pp.51-57
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• 2000

Waste newspapers was used as an amendment to adjust the moisture of household food wastes for composting. The mixture of household food wastes and waste newspapers was composted in an especially designed small home composter, where the early fed composting materials were discharged early. The temperature inside composting materials was influenced very much by that of outside, because the composter was not insulated. Accordingly, the higher the outside temperature was, the higher the decomposition rate was. The temperature inside composting materials did not reach to optimum, because the amount of composting materials added in the composter everyday was too little, and it caused too high water content of discharged compost after 15 weeks. Therefore, it was required that the composter must be insulated to maintain the higher temperature. The inorganic compounds$(K_2O,\;CaO,\;MgO,\;P_2O_5)$ and heavy metals(Zn, Cu, Cr, Cd, Hg, As) were accumulated obviously in produced compost, when dry recycled compost was reused as the amendment for adjusting the moisture.

• Korean Journal of Environmental Agriculture
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• v.31 no.2
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• pp.104-112
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• 2012

BACKGROUND: Agricultural inputs (fertilizer and organic inputs) and water conditions can influence $CH_4$ and $CO_2$ emission from agricultural soils. This study was conducted to investigate the effects of agricultural inputs (fertilizer and organic inputs) under changing water regime on $CH_4$ and $CO_2$ emission from a soil in a laboratory incubation experiment. METHODS AND RESULTS: Four treatments were laid out: control without input and three type of agricultural inputs ($(NH_4)_2SO_4$, AS; pig manure compost, PMC; hairy vetch, HV). Fertilizer and organic inputs were mixed with 25 g of soil at 2.75 mg N/25 g soil (equivalent to 110 kg N/ha) in a bottle with septum, and incubated for 60 days. During the first 30-days incubation, the soil was waterlogged (1 cm of water depth) by adding distilled water weekly, and on 30 days of incubation, excess water was discarded then incubated up to 60 days without addition of water. Based on the redox potential, water regime could be classified into wetting (1 to 30 days), transition (31 to 40 days), and drying periods (41 to 60 days). Across the entire period, $CH_4$ and $CO_2$ flux ranged from 0 to 13.8 mg $CH_4$/m/day and from 0.4~1.9 g $CO_2$/m/day, and both were relatively higher in the early wetting period and the boundary between transition and drying periods. During the entire period, % loss of C relative to the initial was highest in HV (16.4%) followed by AS (8.1%), PMC (7.5%), and control (5.4%), indicating readily decomposability of HV. Accordingly, both $CH_4$ and $CO_2$ fluxes were greatest in HV treatment. Meanwhile, the lower $CH_4$ flux in AS and PMC treatments than the control was ascribed to reduction in $CH_4$ generation due to the presence of oxidized compounds such as ${SO_4}^{2-}$, $Fe^{3+}$, $Mn^{4+}$, and ${NO_3}^-$ that compete with precursors of $CH_4$ for electrons. CONCLUSION: Green manure such as HV can replace synthetic fertilizer in terms of N input, however, it may increase $CH_4$ emission from soils. Therefore, co-application of green manure and livestock manure compost needs to be considered in order to achieve satisfactory N supply and to mitigate $CH_4$ and $CO_2$ emission.

• Korean Journal of Environmental Agriculture
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• v.29 no.4
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• pp.328-335
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• 2010

This study was conducted to determine effects of soil pH and form of nitrogen fertilizers on tomato growth and chemical properties of greenhouse soil using ferigation system. Tomato (Lycopersicon esculentum Mill. cv. Superdoterang) were grown for three months in 18 L pots filled with two soil (pH 6.8 and pH 8.7). 4 different nitrogen fertilizers (urea, ammonium nitrate, ammonium sulfate, and potassium nitrate) were fertigated with different concentrations of 0, 10, 50, and 100 mg N/L during tomato cultivation. Soil pH 8.7 decreased yield and chlorophyll fluorescence compared with soil pH 6.8. Yield at soil pH 8.7 increased by ammonium nitrate and ammonium sulfate fertigation. Soil pH 6.8 induced increment of yield by nitrogen concentration than form of nitrogen fertilizers. Soil pH after cultivation of tomato decreased by application of ammonium nitrate and ammonium sulfate. Soil EC by 100 mg N/L application of ammonium sulfate was twice as much as other fertilizers. Form of nitrogen fertilizer had less effect on concentration of soil $NH_4^+$-N and $NO_3^-$-N in soil but the concentrations slightly reduced at pH 8.7. These results indicate that application of urea and ammonium nitrate for a nitrogen source of fertigation has little affects on soil chemical properties before and after tomato cultivation.

• Korean Journal of Environmental Agriculture
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• v.36 no.1
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• pp.43-49
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• 2017

BACKGROUND: Greenhouse crops are one of agricultural products consumed largely in Korea. Cucumber is a typical example as main vegetables of greenhouse crops. Thus, pesticide residue analysis is an important requirement to guarantee pesticide safety of cucumber. This work was aim to investigate the residues of penthiopyrad and pyriofenone in cucumber after harvest. METHODS AND RESULTS: Cucumber was subjected to treat with penthiopyrad and pyriofenone at a level of recommended dose 0, 1, 2, 3, 5, 7 and 10 days before harvest under greenhouse conditions. The samples were extracted with organic solvent by using a homogenizer and purified on solid phase cartridge column followed by LC-MS/MS analysis. The recovery levels of penthiopyrad and pyriofenoneranged from approximately 81 to 93% with the method limit of 0.005 mg/kg and coefficient of variation less than 10%. Penthiopyrad and pyriofenone were detected at a level less than maximum residue limit in cucumber at 10 days before. The half-lives of penthiopyrad and pyriofenone were determined to 2.4 ~ 2.6 days. CONCLUSION: Penthiopyrad and pyriofenone are suggested to use in cucumber 10 days before harvest to reach their levels less than maximum residue limit.

• Horticultural Science & Technology
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• v.18 no.6
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• pp.834-838
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• 2000

As an endeavor to establish a micropropagation system for Epimedium koreanum Nakai., this study was carried out to define methods to disinfect its explants and media for callus induction, proliferation and plant regeneration. The lowest infection rates by fungi or bacteria on apical and axillary bud explants of rhizome were observed when they were immerged in 0.3% NaOCl solution for 20 min after soaked in 0.1% $AgNO_3$ solution for 30 min, but leaf explants were seldom infected with fungi or bacteria by this disinfectant method. The highest rate of plantlet formation was obtained from the explants disinfected in 0.3% NaOCl solution for 20 min after soaked in 0.1% $AgNO_3$ solution for 60 min for tip buds and in 0.1 % $AgNO_3$ solution for 30 min for axillary buds of rhizome. Induction rate of callus was the highest from the explants disinfectd in 0.3% NaOCl solution for 20 min after soaked in 0.2% $AgNO_3$ solution for 15 min. Callus growth was proper in a modified 1/2 MS medium including half strength of $NH_4NO_3$ with $0.02-0.2mg{\cdot}L^{-1}$ BA and $2.0mg{\cdot}L^{-1}$ NAA. Low rate of plantlet regeneration was obtained in 1/2 UM or 1/2 White medium with $2.0mg{\cdot}L^{-1}$ BA and $0.2mg{\cdot}L^{-1}$ AA.