• Korean Journal of Environmental Agriculture
• /
• v.21 no.2
• /
• pp.130-135
• /
• 2002

Water-dispersible colloids are suspected to facilitate transport of contaminants to groundwater. This study evaluated some soil chemical properties in relation to the stability of colloids in soils of Jeju citrus orchards. Thirty surface soil samples were collected, and pH, organic matter content oxalate-extractable Al and Fe contents, and water-dispersible colloid content were measured. In soils of higher pH, water-dispersible colloid contents were higher. The stability of colloids was found to be significantly promoted at pH above 5$\sim$6. Since organic matter can act as a flocculant organic matter content significantly enhanced the colloid stability. In soils of less than 5% organic C, water-dispersible colloid content was expected to be significantly higher. In soils of higher oxalate-extractable Al and Fe contents, colloids remaining in suspension were lower. This indicated that amorphous oxides and hydroxides play important stabilizing roles in soil structure and can stabilize soil clay against dispersion. Therefore in soils of higher pH, lower organic matter, and lower amorphous clay minerals, the stability of water-dispersible colloids and the potential of colloid-mediated transport of organic chemicals to groundwater could be higher.

• Korean Journal of Soil Science and Fertilizer
• /
• v.41 no.1
• /
• pp.26-33
• /
• 2008

Soil nutrient status in an organic apple farm was evaluated in relation to a conventional farm to better understand the effects of organic farming system on soil fertility. Soil organic matter, total and mineral N, available P, exchangeable cations, and available micronutrients were monitored at depth of 5-20 cm from May to October in 2006. Average soil organic matter content was 63.3 and $31.0g\;kg^{-1}$ in organic and conventional farm, respectively. Total N content was 3.3 and $1.7g\;kg^{-1}$ in average for organic and conventional farm, respectively. Ammonium and nitrate N in organic farming were maintained at relatively stable levels, but in the conventional farm the levels were very high in early season due to the chemical fertilizer application. In the organic apple farm, available P content in May was lower than that found in the conventional farm, but during the growing season available P content was continuously increased and in August the content was more than $1000mg\;P_2O_5\;kg^{-1}$. The organic farm maintained relatively greater exchangeable K, Ca, and Mg levels than the conventional farm. Available Cu, Fe, and Mn contents in the conventional farm were relatively greater than those found in the organic farm. However, available Zn extracted in 0.1 M HCl was much greater in the organic farm. Nutrient levels above crop needs were observed in both conventional and organic apple farm suggesting a more appropriate management of soil nutrients in organic farming to secure its fundamental functions for the sustainable agriculture.

• Korean Journal of Organic Agriculture
• /
• v.19 no.spc
• /
• pp.206-209
• /
• 2011

For the development of Boxthorn organic cultivation techniques, we investigated effect of several organic compost as a foundation fertilizer and growing plant fertilizer. And we adopted partly opening rain shelter greenhouse to protect anthracnose. In organic compost applying test yield characteristics of 'Mixed organic compost' treatment was the best but in betaine content measurement of dried fruit, 'Mixed organic compost and nitrogen guano' treatment was the best and it's chlorophyll and 100 fruit weight were also better than the other treatments.

• Food Science and Biotechnology
• /
• v.16 no.3
• /
• pp.386-391
• /
• 2007

This study was conducted to observe quality characteristics of whole soybean meju fermented with germinated soybean (Glycine max: Hwanggeumkong). The germination rate after 24 hr was $23.0{\pm}1.2%$, then increased rapidly to $90.2{\pm}1.3%$ at 36 hr of germination, and finally reached a level of $99.4{\pm}0.3%$ at 60 hr of germination. It was confirmed that the total isoflavone content immediately after soaking was 100.1 mg%, increasing during the beginning of the germination process; it continued to increase to 114.0 mg% by 24 hr of germination, but decreased thereafter. The isoflavone content at 60 hr of germination was 101.6 mg%. A total of 6 organic acids were detected, and total organic acid content ranged from 963.1-1,145.3 mg%. Differences based on the degree of germination in the raw material were insignificant. The free amino acid levels of the whole soybean meju made from non-germinated soybeans and from soybeans that had germinated 48 hr were 2,580.9 and 2,519.7 mg%, respectively. The content of glutamic acid was highest followed by aspartic acid, lysine, leucine, and proline.

• Polymer(Korea)
• /
• v.31 no.4
• /
• pp.349-355
• /
• 2007

Poly(N-isopropylacrylamide-co-acrylonitrile) [P(NIPAAm-co-AN)] copolymers with AN content of up to 10 mol% and their hydrogels were synthesized using water as a reaction medium, and the effects of AN unit incorporation on the critical gel transition temperature(CGTT) and swelling behaviors of the hydrogels were investigated. The CGTT of the copolymer hydrogel was $30{\sim}32\;^{\circ}C$, decreasing with increasing AN content. Below CGTT, swelling rate and equilibrium swelling ratio of the copolymer hydrogel decreased with increasing AN content. On the other hand, it exhibited faster deswelling and lower equilibrium deswelling ratio with increasing AN content above CGTT.

• Journal of Environmental Science International
• /
• v.20 no.3
• /
• pp.385-394
• /
• 2011

Organotin compounds (OTs), namely butyltins compounds (BTs) and phenyltin compounds (PhTs), were measured in surface and core sediments collected in Jeju harbor. The horizontal and vertical distribution was examined and the relationship between the concentration of OTs and organic matter content and particle size distribution was also studied. BTs were detected in significant concentrations in sediments inside Jeju harbor. PhTs were detected in very low concentrations, compared to BTs. The main species in BTs and PhTs were dibutyltin (DBT) and monobutyltin (MBT), monophenyltin (MPhT), respectively. In the relationships between the concentrations of total BTs and organic carbon content, the significant correlations ($r^2$=0.4898 in surface sediments, $r^2$=0.53 in one core sediments) and no correlation in another core sediments obtained, which is estimated that the distribution of BTs in sediments were affected by several factors, such as their physicochemical properties including organic carbon content, and a tide, etc. In the relationships between the concentrations of total BTs and particle size (mud, sand, and gravel) in sediments, the concentrations of total BTs were higher in the sediments with higher mud content, indicating that higher BTs were distributed with increasing sediments of fine granules.

• Food Science and Preservation
• /
• v.4 no.1
• /
• pp.77-85
• /
• 1997

This study aims to determine the optimal picking time and the favorate variety for Ume processing. The changes of physicochemical components and flavors of 6 varieties of the Ume were investigated during maturing. Average weight of the fruit increased to the range of 151-292% from 70 days to 90 days after blooming. The hardness of fruit decreased during maturing and Koume variety was not suitable for processing among the last harvesting samples. Moisture and ash were reached to 89-91%, 0.57-0.69%, respectively, and the ash content increased during maturing. Among the Ume varieties, relatively high content of total acid was observed in Oshuku and Koume. The major organic acid were malic, citric, succinic, and tartaric acid. The content of malic acid decreased significantly, whereas citric acid increased during maturing. Thirty five kinds of flavor components were identified from the Ume fruit and main components were ethyl acetate, butyl acetate, and organic acid derivatives. Koume contained a large amount of flavor components among the Ume and the content increased during maturing.

• Journal of Environmental Science International
• /
• v.32 no.3
• /
• pp.181-189
• /
• 2023

In this study, sediment cores from unvegetated tidal flats in the Hampyeong Bay (west coastal wetland) and Dongdae Bay (south coastal wetland) were sampled, the blue carbon stock in the sediments was calculated, and the characteristics of the blue carbon stock were analyzed based on particle size of the sediments. The sediments in the Hampyeong Bay tidal flat had large particle size and low mud content, and the Dongdae bay tidal flat had small particle size and high mud content. The organic carbon content and blue carbon stock in the sediments were higher in the Dongdae tidal flat than in the Hampyeong Bay tidal flat. As a result of the regression function, in both the Hampyeong Bay and Dongdae Bay tidal flats, the sediments had the smaller particle size and higher mud contents the higher the organic carbon content and blue carbon stock. The sediments with smaller particle size had the larger specific surface area, so were feasible to adsorb and store more organic matters.

• Korean Journal of Soil Science and Fertilizer
• /
• v.49 no.5
• /
• pp.510-516
• /
• 2016

Soil respiration has been recognized as a key factor of the change of organic matter and fertility due to the carbon and nitrogen mineralization. In this study, we evaluated the effect of soil respiration on the light fraction-C and inorganic N content depending on temperature in soil applied with organic matter. Soil respiration was calculated by using total $CO_2$ flux released from soil applied with $2Mg\;ha^{-1}$ of rice straw compost and rye for 8 weeks incubation at 15, 25, $35^{\circ}C$ under incubation test. After incubation test, light fraction and inorganic N content were investigated. Rye application dramatically increased soil respiration with increasing temperature. $Q_{10}$ value of rye application was 1.69, which was higher 27% than that of rice straw compost application. Light-C and $NO_3-N$ contents were negatively correlated to soil respiration. Light-C in rye application more decreased than that in rice straw compost with temperature levels. These results indicate that temperature sensitivity of soil respiration could affect soil organic mater content and N availability in soil due to carbon availability. Also, light fraction would be useful indicator to evaluate decomposition rate of organic matter in soil under a short-term test.

• Korean Journal of Food Science and Technology
• /
• v.17 no.5
• /
• pp.403-405
• /
• 1985

The composition of fatty acids and organic acids in the fruits, stems, and roots of Acanthopanax were studied. The major fatty acids in the fruits, stems and roots were oleic, linoleic and palmitic acids and these composed about 86-98% of total fatty acids. However, there are great differences in content of the major fatty acids between varieties and each parts. Citric, malefic, succinic, malonic, fumaric and malic acids were identified in the fruits. Malic acid was the predaminant organic acid. There are great differences in individual content of the organic acids between varieties and each parts. Malonic and malefic acids were not detected in the stems and roots, respectively. Citric acid was most abundant organic acid parts. Total organic acid content in roots was very low compared to that of fruits and stems.