• Korean Journal of Soil Science and Fertilizer
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• v.45 no.1
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• pp.30-36
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• 2012

The active fraction of soil organic matter, which includes organic debris and light organic fraction, plays a major role in nutrient cycling. In addition, particulate organic matter is a valuable index of labile soil organic matter and can reflect differences in various soil behaviors. Since soil organic matter bound to soil mineral particles has its density lower than soil minerals, we partitioned soil organic matter into debris ($<1.5g\;cm^{-3}$), light fraction ($1.5-2.0g\;cm^{-3}$), and heavy fraction ($>2.0g\;cm^{-3}$), based on high density $ZnCl_{2-}$ sucrose solutions. Generally, partitioned organic bands were clearly separated, demonstrating that the $ZnCl_{2-}$ sucrose solutions are useful for such a density gradient centrifugation. The available gradient ranges from 1.2 to $2.0g\;cm^{-3}$. Although there was not a statistically meaningful difference in organic debris and organomineral fractions among the examined soils, there was a general trend that a higher content of organic debris resulted in a higher proportion of light organomineral fraction. In addition, high clay content was associated with increased fraction of light organomineals. Partitioning of soil organic carbon revealed that carbon content is reduced in the heavy fraction than in the light fraction, reflecting that the light fraction contains more fresh and abundant carbon than the passive resistant fraction. It was also found that carbon contents in the overall organic matter, debris, light fraction, and heavy fractions may differ considerably in response to different farming practices.

• Korean Journal of Organic Agriculture
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• v.19 no.spc
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• pp.225-229
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• 2011

Organic kiwifruits were smaller fruit size but had higher magnesium and dry matter content than conventional, meanwhile, fruit soluble solid content was similar to conventional. There were no significant difference in polyphenol contents and antioxidative capacity between organic and conventional although there were considerable variations among sample orchards. Several minerals were also similar levels in both systems.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.223-223
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• 2017

This study aimed to determine the effect of organic matter content and water condition in soil on yield, carbohydrate, and inulin contents of two varieties of Jerusalem artichoke. The plants were grown with high and low organic soil either under irrigation or no irrigation in a randomized complete block design (RCBD) with three replications. In result, the yield of Jerusalem artichoke was higher about 7 kg in soil with high organic matter than in soil with low organic matter, while it was higher about 11 kg under the irrigation than under no irrigation. The yield of white variety was higher about 9 kg than that of purple variety. Under the irrigation, a 12 kg and 9 kg of higher yields were observed in the soil with high and low organic matter content, respectively, than under no irrigation.

• Korean Journal of Plant Resources
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• v.33 no.3
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• pp.194-199
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• 2020

This study was carried out to get the information of Plum tree (192 germplasm) collected in Korea, and to evaluate the organic acid contents and fermentation solution. The organic acid content of fruit was 50.9 ± 6.0 mg/g, and which was composed of 55.5% of citric acid, 43.4% of malic acid and 1.1% of oxalic acid, and showed large difference among germplasms. Oxalic acid and malic acid made no differences in organic acid content according to flesh color, whereas citric acid and total organic acid contents were highest in orange color and lowest in whitish green. Malic acid, citric acid and total organic acid contents did not show differences among fruit weight groups, but oxalic acid content was highest at fruit weight of 5.1 ~ 10.0 g and lowest at more than 20.1 g. The sugar content of fermentation solution of fruit was 55.7 ± 1.6 °Brix and the harvest rate was 116.7 ± 8.7%. The correlation coefficients among fruit weight, the sugar content (°Brix) and harvest rate of fermentation solution were very low, and there were correlations of r=-0.551^⁎⁎ between fruit weight and oxalic acid, r=-0.767^⁎⁎ between malic acid and citric acid, and r=0.834^⁎⁎ between citric acid and total organic acid content.

• Korean Journal of Organic Agriculture
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• v.2 no.1
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• pp.2-15
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• 1993

Major vegetables and fruits in Korea are grouped in 3 Categories according to the Concentration of NO3- content in edible parts of the plant. NO3- content are high in order fruit

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.3
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• pp.471-476
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• 1998

The NO3 contents and organophosphorus pesticide residues in edible part of vegetables cultivated by a conventional or an organic farming methods were determined. The NO3 contents of vegetables cultivated by the organic farming method were between 120ppm and 4,523ppm, whereas its contents of vegetables cultivated by the conventional farming method were between 89ppm and 1,575ppm. Fifty two percent of vegetables cultivated by hte organic farming method accumulated NO3 content over than 2,000ppm, whereas 82% vegetables cultivated by the conventional farming method accumulated NO3 content below than 1,000ppm. The NO3 contents of lettuce dependent on the cultivation method obviously. The NO3 contents of lettuce cultivated by a hydroponic farming method were between 4,800 and 6,500ppm, whereas those cultivated by the conventional method were between 630 and 750ppm. The organophosphorus pesticide residues in edible part of vegetables cultivated by the conventional or the organic farming methods were not detected. The NO3 contents in edible part of vegetables cultivated by the organic farming method should be considered as one of several parameters to judge a real safe vegetable to be certified by goverment.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.6
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• pp.939-944
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• 1994

The change of major organic acid contents were examined in mackerel, pacific yellow croaker and brown sole on heating conditions. The organic acid contents of mackerel were the higher that the others. The content of lactic acid was the highest in all samples commonly and that of succinic acid was second level and these organic acids were over 95% of total organic acid. The content of ${\alpha}-ketoglutaric$ acid was higher acid content was greater with higher heating temperature. Decreasing of organic acid content was higher at steamed and first heating than warmed and rewarmed.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.2
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• pp.3-9
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• 2006

The chemical fractions of phosphorus were investigated in the soils of reclaimed and natural tidelands of southwest coastal area of Korea. The content of total-P varied to ranged from 322 to 614 mg/kg dry weight with a mean value of 467 mg/kg. The order of different fractions of phosphorus in reclaimed tideland soils was as follows: 1) inorganic phosphorus: Ca-P > Fe-P > Al-P > reductant soluble Fe-P. 2) organic phosphorus: Inositol-P > nucleic acid-P > phospholipid-P. The content of Al-P showed negative correlation with organic matter content but showed positive correlation with pH. The content of Fe-P showed negative correlation with clay mineral content but showed positive correlation with organic matter content. Reductant soluble Fe-P and Ca-P were no correlation with soil properties. The content of inositol-P showed highly positive correlation with clay mineral, organic matter content, and CEC.

• KSBB Journal
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• v.25 no.1
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• pp.103-107
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• 2010

Oil degradation agent was developed with organic sludge and modified peat moss (MPM) to recover oil contaminated soil. Waste sludge discharged from wastewater treatment plant of chemical plant in Ulsan National Industrial Park was used as organic sludge, and MPM was purchased. Organic sludge was adequate to use as growth medium for microorganism, the surface of MPM had porous structure which could enhance the cultivation condition of oil degradation microorganisms. Water contents and TPH variation with time were observed to investigate the degradation capacity of developed degradation agent. Water contents were rapidly decreased with higher contents of MPM, however, in case of TPH, high MPM content decreased the degradation capacity. Therefore, it was recommended that the content of MPM was controlled to below 10% in degradation agent as mixing organic sludge with MPM.

• Korean Journal of Organic Agriculture
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• v.7 no.2
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• pp.125-151
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• 1999

After the release of facts that the high nitrate contents in vegetables by Korean organic farming, organic farmers were recommended by Korean Organic Farmer Association to apply 20t/ha compost while they applied before as much as they could, sometimes even more than 100t/ha. This study was aimed to check the safety of Korean organic product in terms of nitrate content. Current nitrate content in leaf and root vegetables by 3 different farming systems(organic farming, conventional farming, greenhouse farming) were monitored and furthermore it was compared with previously published another data in Korea to find out any changes among the monitored years(1993-1999). Current nitrate content in chinese cabbage, lettuce and kale became less compare to those of the beginning of monitoring, and especially those cultivated organic farming got the lowest value while previous organic vegetables at beginning of 90's showed the higher value than those cultivated in greenhouse. This decrease in organic vegetables was affected by less application rate of organic fertilizer than before at 20t/ha. But the nitrate level by organic farming was still higher compare to those cultivated by conventional farming in open field, since currently monitored organic vegetables were cultivated basically in greenhouse condition. It shows the organic farmer the necessity of transfer their farming site and condition from greenhouse to open field in order to decrease of its high level of nitrate caused long-term application and slow release characteristics of organic fertilizer. It was concluded the adoption of soil nitrate test to recommend a organic farmer the exact application rate for need of crop growth. Additionally the mechanism of lower nitrate accumulation in rice and fruit vegetables were also discussed in the paper.