• Applied Biological Chemistry
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• v.44 no.3
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• pp.206-207
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• 2001

• The Korean Journal of Ecology
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• v.17 no.2
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• pp.171-183
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• 1994

Soil condition, total number of bacteria, soil amylase activity and microbial biomass $(CO_2-C)$ were measured at soil of different forest types. And the difference of the allelopathic effect was determined between fresh leaf extract of Quercus acutissima and Pinus rigida to the bacteria isolated from soil of different forest types. 1. Total number of bacteria in Carpinus laxiflora forest soil was 4~7 times larger than that in pinus desiflora forest soil. 2. Soil amylase activity was positively correlated with total number of soil bacteria and soil organic matter content. The amylase activity at F layer was 4~5 times larger than that at H layer, and that at H layer was 2~4 times larger than that at A layer. 3. Seasonal changes of microbial biomass showed a peak in summer, and vertical distribution of microbial biomass decreased with increasing soil depth. The microbial biomass in Pinus densiflora forest soil was larger than that in Quercus serrata forest soil. 4. Fresh leaf extract of Pinus rigida and Quercus acutissima showed an acceleration or inhibition effect on the growth of soil bacteria, and that of !. acutissima inhibited larger number of soil bacterial strains than that of P. rigida. 4.2% and 25% of soil bacterial strains isolated from soil of P. rigida and Q. acutissima forests were inhibited by fresh leaf extract of P. rigida and Q. acutissima, respectively.

• Korean Journal of Environmental Agriculture
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• v.34 no.1
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• pp.1-5
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• 2015

BACKGROUND: The stabilities of the two alkaloidal insecticides of S. flavescens including matrine and oxymatrine are important factor to establish expiry date and usage manual for crop protection. However, the environmental stability of the compounds had not been studied with the extract and its commercial biopesticide. METHODS AND RESULTS: The environmental stabilities of the two alkaloids were performed with extract of S. flavescens, and its two commercial biopesticides both in controlled aquatic and soil conditions. The half-lives of the total matrines for the extract and its two commercial biopesticides were estimated over 200 days both under aerobic and anaerobic water condition. Under dry soil condition, the initial decay rates of the matrines were calculated 0.0804-0.1275 ($t_{1/2}$ 5.4-8.6 days), and the half-lives under wet soil condition were calculated 33.0-231 days. Total soil bacteria on the wet soil ranged 6.0-8.0 log CFU/g-soil during the experiments period. CONCLUSION: The aquatic mixture of the extract showed excellent stability both with the extract and its biopesticides, however, the stability of soil mixture were shorter than the aquatic mixture, suggesting that soil metal consider as a catalyst for the degradation of the two alkaloids.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.1
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• pp.71-75
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• 2001

Linear regression analyses between the electrical conductivity of the saturation-paste extract. ECe, and the electrical conductivity of the 1:5 soil extract, EC1:5, for different soils yielded different dilution factors, or slopes with significant $r^2$ values from 0.842 to 0.905. The dilution factor was inversely proportional to the cation exchange capacity of soil which reflected textural difference. The dilution factors recommended for different textural classes ranged from 6.44 for clay soil to 12.29 for sandy soil based on the CEC's of the textural classes among 350 surface soils recorded in the Taxonomical Classification of Korean Soils except volcanic ash derived soils. Though saturation percentage of the saturation-paste of the soils in this study, CEC should be taken into account for dilution factor between ECe and EC1:5, and the suggested dilution factors might be reasonable estimate for the soil textural classes.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.5
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• pp.391-398
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• 2013

Soil organic carbon (SOC) has the potential to promote the soil quality for sustainability and mitigation of global warming. There is little information on organic carbon composition despite of having resistance of carbon degradation in soil. In this study, to understand the effect of volcanic ash on organic carbon composition and quantity in soil, we investigated characteristics of volcanic soil and compared organic carbon composition of soil and humic extract by using $^{13}C$-CPMAS-NMR spectra under soil profiles of Namweon series in Jeju. SOC contents of inner soil profiles were 134.8, 101.3, and 27.4 g C $kg^{-1}$ at the layer of depth 10-20, 70-80 and 90-100 cm, respectively. These layers were significantly different to soil pH, oxalate Al contents, and soil moisture contents. Alkyl C/O-alkyl C ratio in soil was higher than that of humic extracts, which was decreased below soil depth. Aromaticity of soil and humic extract was ranged from 29-38 and 24-32%, which was highest at the humic extract of 70-80 cm in soil depth. These results indicate that the changes of SOC in volcanic ash soil resulted from alteration of organic composition by pyrolysis and stability of organic carbon by allophane in volcanic ash soil.

• Korean Journal of Environmental Agriculture
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• v.29 no.1
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• pp.7-11
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• 2010

This experiment was conducted to investigate the growth inhibition effects caused by continuous cropping soil in peony(Paeonia lactiflora Pallas). The effect of extracts from continuous cropping soil of peony was tested with bio-assay method using callus cells induced from peony filament tissues and seedlings derived from peony zygotic embryos. The cell viability and seedling growth were significantly inhibited by methanol extract in continuous cropping soil. Methanol extract from continuous cropping soil was successively fractionated with solvents such as n-hexane, ethyl acetate, n-butanol and water. The seedling growth was inhibited by ethyl acetate fraction obtained in methanol extract.

• Journal of Soil and Groundwater Environment
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• v.20 no.3
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• pp.83-91
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• 2015

Mine soil contamination by high levels of metal ions that prevents the successful vegetation poses a serious problem. In the study presented here, we used the microbial biocatalyst of urease producing bacterium Sporosarcina pasteurii or plant extract based BioNeutro-GEM (BNG) agent. The ability of the biocatalysts to bioremediate contaminated soil from abandoned mine was examined by solid-state composting vegetation under field conditions. Treatment of mine soil with the 2 biocatalysts for 5 months resulted in pH increase and electric conductivity reduction compared to untreated control. Further analyses revealed that the microbial catalysts also promoted the root and shoot growth to the untreated control during the vegetation treatments. After the Sporosarcina pasteurii or plant extract based BNG treatment, the microbial community change was monitored by culture-independent pyrosequencing. These results demonstrate that the microbial biocatalysts could potentially be used in the soil bioremediation from mine-impacted area.

• Journal of Soil and Groundwater Environment
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• v.23 no.1
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• pp.85-91
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• 2018

Arsenic (As) usually is bound to amorphous iron oxides in the soils, and it can be removed via dissolution of iron oxides. Inorganic acid and chelating agent are widely used to extract As in the soil washing. However, the overall performance is highly dependent on the state of As fractionation. In this study, oxalic acid and inorganic acids (HCl, $H_2SO_4$, and $H_3PO_4$) were applied to enhance the dissolution of iron oxides for remediation of As-contaminated soils. Oxalic acid was most effective to extract As from soils and removal of As was two times greater than other inorganic acids. Additionally, 75% of As bound to amorphous iron oxides was removed by 0.2 M oxalic acid. Arsenic removal by oxalic acid was directly proportional to the sum of labile fractions of As instead of the total concentration of As. Therefore, the oxalic acid could extract most As bound to amorphous iron oxides.

• Korean Journal of Microbiology
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• v.26 no.2
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• pp.122-128
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• 1988

The enzymatic properties of soil cellobiohydrolase were examined and compared with those of cellobiohydrolase-active extracts from soil in the forms of enzyme-humic complex and humicfree enzyme, and cellobiohydrolase partially pruified from Aspergillus niger. The pH optima of soil cellobiohydrolase and cellobiohydrolase-humic complex were greater by 1.5-3.0 pH units than those of cellobiohydrolase in humic-free extract and from A. niger. Soil cellobiohydrolase and cellobiohydrolase-humic complex were remarkably resistant to thermal denaturation and proteolysis. These results confirm that cellobiohydrolase in soil is atable in conditions which rapidly inactivate microbial cellobiohydrolase and that its stability is due to the immobilization of this enzyme by association with humic substances. The Michaelis-Menten constants (Km) for soil, cellobiohydrolase-humic complex, humic free extract and cellobiohydrolase from A. niger were 22.1mg/ml, 11.3mg/ml, 10.6mg/ml and 4.5 mg/ml of Avicel, respectively.

• Korean Journal of Environmental Agriculture
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• v.38 no.2
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• pp.69-75
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• 2019

BACKGROUND: Measurement of electrical conductivity of saturated soil paste ($EC_e$) for assessment of soil salinity is time-consuming, and thus conversion of EC of 1:5 soil-water extract ($EC_{1:5}$) to $EC_e$ using a dilution factor may be of help to monitor salinity of huge number of soil samples. This study was conducted to evaluate the dilution factor for reclaimed tideland (RTL) soils of South Korea. METHODS AND RESULTS: Soil samples (n=40) were collected from four RTLs, and analyzed for $EC_{1:5}$, $EC_e$, and cation compositions of 1:5 soil-water extract. The dilution factor (8.70) was estimated by regression analysis between $EC_{1:5}$ and $EC_e$, and the obtained dilution factor was validated by applying to an independent data set (n=96) of $EC_{1:5}$ and $EC_e$. The $EC_e$ measured and predicted was strongly correlated ($r^2=0.74$, P<0.001), but $EC_e$ was overestimated by 16% particularly for the soils with high clay content and low sodium adsorption ratio (SAR). CONCLUSION: This study suggests that using the dilution factor to convert $EC_{1:5}$ to $EC_e$ is feasible method to monitor changes in the soil salinity of the study RTL. However, overestimation of $EC_e$ should be cautioned for the soils with high clay content and low SAR.