• Korean Journal of Soil Science and Fertilizer
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• v.29 no.2
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• pp.158-164
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• 1996

This survey was conducted to investigate the distribution of heavy metal contents in medicinal plants and soils. Plant and soil samples were collected at 254 sites(Angelica gigas : 81, Astragalus membranceus : 38, Platycodn glandiflorum : 36, Paeonia albilora : 34, Codonopsis lanoceolata : 32, Ligusticum chuanxiong : 17, Bupleurum falcatum : 16, respectively) over the country, Soil texture, pH values and heavy metal content of soils and medicinal plants were evaluated as major factors. Soil texture classification showed that sandy loam, loam, loamy sand and silt loam were 46.1%, 26.0%, 19.3% and 8.6% of the total, respectively. The contents of O.M, Ex.Ca. Ex.Mg and EC value were higher in loamy(sandy loam, loam and silt loam)soils than in sandy(loamy sand)soils, but available $P_2O_5$ contents of loamy sand soils were higher than those of sandy loam, loam, and silt loam. The contents of Cd, Cu, Pb, Zn and Ni in soil were high in loamy soils, while Cr content was high in loamy silt soils. The contents of Cu and Cr in Angelica gigas were high in loamy soils, and those of Pb in Astragalus membranceus, Paeonia albiflora and Codonopsis lanoceolata were high in sandy loam soils. Correlation coefficients between heavy metal contents in medicinal plants and their soils with soil texture were positively correlated in sandy loam and loam at Cu, loam at Zn, sandy loam, loam and loamy sand at Cr, respectively. Correlation coefficients between pH value of the soils and contents of Cd, Zn and Ni in medicinal plants were negatively correlated, but those of Cd, Pb, Zn and Ni in soils were positively correlated.

• Journal of Environmental Impact Assessment
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• v.17 no.6
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• pp.321-333
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• 2008

Considering risks and artificial enrichments of metals in the soils of the study area, the study aims to analyze geology, grain size and geochemistry. Geology is mainly composed of gneisses and phyllites of metamorphic rocks, sandstones, siltstones, shales, tuffs of sedimentary ones and granites and andesites of igneous ones in the area. In the area, mean contents of metals are not meaningful in accordance with petrogenesis. The soil textures of the area are of S, lS and sL of sandy soil, L, scL, cL of loam and C, zC and sC of clayey soil. Mean contents of Ni, Cr, Co and Cu are meaningfully high in loam and clayey soil relative to sandy soil, whereas Ni, Zn, Cd contents are higher in clayey soil than in loam. Those differences imply the metallic contents are dependent to grain size. Based on the metal contents in the soils of the study area, Cu and Zn in loams and Pb in sandy soils are corresponded to soil contamination warning standards, and As showing 75mg/kg of maximum content in loams is assigned to soil contamination countermeasure standards, respectively. Artificial enrichment factor minimized wall rock and grain size relations is over 1 in Cr, Ni and Cu, but the factor is below 1 in average of other metals.

• Journal of the Korean Geotechnical Society
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• v.18 no.3
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• pp.126-126
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• 2002

In dynamic analyses such as seismic ground response and soil-structure interaction problems, it is very crucial to obtain accurate dynamic shear modulus of soil deposit. In this study, an extensive data base of available experimental data is compiled and reanalyzed to establish a simple empirical formula for the dynamic shear modulus reduction curve to cover wide range of strain for sandy soils. The proposed empirical equation is to represent the dynamic shear modulus degradation with strain in terms of low-amplitude dynamic shear modulus and effective mean confining Pressure, since those factors have the most significant effect on the Position and shape of the shear modulus reduction curve for nonelastic soils. If low-amplitude shear modulus is measured, degraded modulus at any shear strain amplitude can be calculated using the proposed equation.

• Journal of the Korean Geotechnical Society
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• v.18 no.3
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• pp.127-138
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• 2002

In dynamic analyses such as seismic ground response and soil-structure interaction problems, it is very crucial to obtain accurate dynamic shear modulus of soil deposit. In this study, an extensive data base of available experimental data is compiled and reanalyzed to establish a simple empirical formula for the dynamic shear modulus reduction curve to cover wide range of strain for sandy soils. The proposed empirical equation is to represent the dynamic shear modulus degradation with strain in terms of low-amplitude dynamic shear modulus and effective mean confining Pressure, since those factors have the most significant effect on the Position and shape of the shear modulus reduction curve for nonelastic soils. If low-amplitude shear modulus is measured, degraded modulus at any shear strain amplitude can be calculated using the proposed equation.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.1
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• pp.22-28
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• 2011

With the increasing cultivation of acid-loving plants such as blueberries, the artificial acidification of soils is frequently required. This research was conducted to determine the application rates of elemental sulfur (S) required in the soil acidification for blueberry cultivation. Laboratory incubation experiment was conducted to acidify three arable soils (pH 6-7) of different texture to pH 4.5-5.0 by the addition of varying amounts of elemental S. All rates of elemental S addition reduced soil pH, although the efficacy of acidification was related to the application rate and soil characteristics. pH reduction was slow in sandy loam soil, and the final equilibrium pH was obtained after 60, 43, and 30 days of incubation in sandy loam, loam, and silty clay, respectively. Although the final pHs obtained after 93 days of incubation were not significantly different among the three soils, the equilibrium pH was relatively higher in soil of higher clay content in the application rates of 1.5-2.0 g S $kg^{-1}$ soil. The estimated amounts of elemental S required in lowering pH to 4.5-5.0 were 0.59-1.01, 0.67-1.03, and 0.53-0.88 g S $kg^{-1}$ for sandy loam, loam, and silty clay, respectively. The lowest estimated amount of elemental S in the acidification of silty clay soil was attributable to the low organic matter content. For clay soils containing optimum level of organic matter, the application rates of elemental S should be much higher than those values estimated in this research. Soil acidification did not significantly increase the available concentrations of Ca, Mg and K. Extractable Cu and Zn was not greatly affected by the acidification, but extractable Fe, Mn, and Al in the acidified soils were higher than those found in non-acidified soils. Such increases in solubility are attributable to the dissolution of oxides and hydroxides of the elements.

• Asian Journal of Turfgrass Science
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• v.5 no.2
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• pp.87-94
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• 1991

This study was carried out to determine the optimal seeding rate of Korean lawngrass in three different soil textures. The results obtained are summarized as follows;1.In early development, there were not significant differences in leaf length and width except for leaf width in mean seeding rates. And there was significant difference in tillering number. Tillering number of Korean lawngrass grown in sandy clay loam soil was more abudant than that grown in sandy clay and sandy loam soils.2.The rate of ground cover of Korean lawngrass grown in sandy clay loam soil was faster than that in other soils. The ground cover rate was faster in the following order: 15, 12, 10, 7, 5, 3 kg/10a. But in sandy clay loam soil, it was showed that the plot seeded at 12kg/10a be faster than that at l5kg/10a. Plots seeded from 5 to 15kg/10a in sandy clay loam soil and 15kg/10a in sandy clay soil were showed the 100% ground cover during the period of the year seeded.3.There were not significant differences in dry weight of each part measured at 11 and l4months after seeding. But there were significant differences in dry weight of shoot and total dry weight. Total and shoot dry weight of Korean lawngrass grown in sandy clay loam soil were heavier than that in others. 4.It was revealed that the optimal seeding rate in sandy clay loam soil was 12 kg/10a. But it was suggested that the optimal seeding time and rate in each soil textures be undertaken in future.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.3
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• pp.249-255
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• 1995

This study was conducted to investigate the effects of some soil conditioners, such as polyacrylamide(PAM), polyvinylalcohol(PVA) and Bitumen emulsion, on aggregate formation and stability, wetting angle, sorptivity and penetrability of the soil with different textures : sand, sandy loam, loam and clay loam. A pot experiment was carried out to find out the effect of treatment on the germination and growth of lettuce with three textures : sand, sandy loam and silt loam. Soil aggregates larger than 2mm in untreated soils at dry condition were naught in sand, 45% in sandy loam, 80% in loam and 90% in clay loam. Treatments of soil conditioners tended to increase the occurrence of soil aggregate larger than 2mm, which were 20~25% in sand, 55~75% sandy loam, but not affected greatly aggragate occurence in loam and clay loam. The aggregate instability was decreased by the soil conditioner treatment. The wetting angles of the soils were greatly changed by hydrophobic of Bitumen, but those were changed slightly by PVA and PAM application. The sorptivity and penetrability data indicated that the effects of different materials on these parameters differed depending upon soil texture. Application of PVA and PAM were no effect exceptive in sand. Application of Bitumen revealed that water movement was not showed in all soils. The germination rate, root weight and top plant weight of lettuce were increased in all soils by PAM treatment as compared to untreated soils. Particularly the greater effect was occurred in sand soil than in sandy loam and silt loam. PAM increased greatly the moisture content and air phase of soils.

• Geomechanics and Engineering
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• v.16 no.5
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• pp.547-558
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• 2018

Studies of soil dynamic properties in Malaysia are still very limited. This study aims to investigate the dynamic properties of two selected tropical residual soils (i.e., Sandy Clay and Sandy Silt) and a sand mining trail (Silty Sand) in Peninsular Malaysia using 1g shaking table test. The use of 1g shaking table test for soil dynamic testing is often constrained to large strain level and small confining pressure only. Three new experimental setups, namely large laminar shear box test (LLSBT), small chamber test with positive air pressure (SCT), and small sample test with suction (SSTS) are attempted with the aims of these experimental setups are capable of evaluating the dynamic properties of soils covering a wider range of shear strain and confining pressure. The details of each experimental setup are described explicitly in this paper. Experimental results show that the combined use of the LLSBT and SCT is capable of rendering soil dynamic properties covering a strain range of 0.017%-1.48% under confining pressures of 5-100 kPa. The studied tropical residual soils in Malaysia behaved neither as pure sand nor clay, but show a relatively good agreement with the dynamic properties of residual soils in Singapore. Effects of confining pressure and plasticity index on the studied tropical residual soils are found to be insignificant in this particular study.

• Journal of Environmental Health Sciences
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• v.22 no.3
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• pp.116-122
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• 1996

This study has been focused on the applicability of microwave treatment of soil contaminated by volitile organic chemicals. Substrates studied were sand and sandy soil. These substrates were impregnated with toluene, tetrachloroethylene, o-xylene and p-dichlorobenzene. The microwave treatment was conducted in a modified domestic microwave oven: 2450 MHz, 700 W. The sandy soil temperature added water went up rapidly to about 130$\circ$C for 4 minutes. And then, the temperature appeared to plateau out. A series of tests were performed to depict the effectiveness of microwave treatment technique to organic contaminants from soils. Removal efficiencies in sandy soil and sand were increased with increasing water content and exposure time. Microwave radiation penetrates the soil and heats water throughout the matrix. Therefore, addition of a certain amount of water to the contaminated soil can efficiently enhance the ability of the soil to absorb microwave energy and promote the evaporation of the volitile contaminants. And the vapour pressure of impregnated organic contaminants becomes lower. the removal efficiency becomes poor.

• Korean Journal of Environmental Agriculture
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• v.25 no.1
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• pp.71-76
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• 2006

Environment friendly agriculture is nowadays a major fiend to sustain balanced agricultural ecosystem, keeping its productivity. This study was conducted to determine the optimum levels of nitrogen (N) application for improving rice productivity and reducing N loss through N application based on soil diagnosis. four levels of N were applied with 0, 50, 100 and 150% of recommended levels by soil testing in 4 different paddy soils (i.e. normal, sandy, ill-drained and immature soils). Across N treatments, the greatest grain yield was observed in sandy soil and the lowest in ill-drained soil. The grain yield tended to decrease with increasing N application from 50% to 150% of recommended levels, except ill-drained soil. To ensure maximum yield the optimum levels of N application were estimated at 120 kg, 153 kg and 173 kg $ha^{-1}$ in normal, immature and sandy soil, respectively.