• Journal of Korean Society of Forest Science
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• v.90 no.3
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• pp.242-248
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• 2001

Changes in land-use can affect soil organic matter content and fertility. We compared total soil carbon and nitrogen concentrations, soil respiration, and nitrogen availability under three land-use types in central Korea; conversion of old rice field to natural willow-maple (Salix-Acer) forest, conversion of old field to artificial Korean pine (Pines koraiensis) forest, and indigenous oak (Quercus spp.) forest. After 20 years of fallow the area of rice field conversion to forest had higher soil carbon and nitrogen concentrations in the soil depth of 0-10cm and 10-20cm than the areas of field conversion to Korean pine forest and indigenous forest. In general, soil carbon and nitrogen concentrations decreased with soil depth. Organic matter accumulation as a balance of input and decomposition seemed to be higher in the soil of previous rice field, and carbon and nitrogen accumulation was largely confined to the topsoil. Soil respiration rates were greatest at the area of rice field conversion to forest, and appeared to be related to soil carbon and soil moisture. Soil nitrogen availability measured by the ion exchange resin bag method differed significantly among land-use types; soil inorganic nitrogen ($NH_4{^+}+NO_3{^-}$) and ammonium availability were highest in the soil under indigenous oak forest followed by conversion of old field to artificial Korean pine forest and conversion of old field to natural willow-maple forest.

• Journal of Applied Biological Chemistry
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• v.60 no.4
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• pp.301-306
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• 2017

This study was carried out to investigate the residual level of 5-methyl-1,2,4-triazolo[3,4-b][1.3] benzothiazole (tricyclazole) and the amount of transfer to Korean cabbage grown in treated soil with tricyclazole. The field trial on Korean cabbage was done at two different green houses located in Gwangju (Field 1) and Yongin (Field 2). Soil and cabbage samples were collected at different days after soil treatment of tricyclazole with two different concentration levels, respectively. Average recoveries of tricyclazole ranged from 83.5 to 92.1% in soil and cabbage and the variation coefficient was 1.3-6.8%. The initial concentrations of tricyclazole in field 1 soil were 4.25 and 8.97 mg/kg and decreased to 2.48 and 4.26 mg/kg at 43 DAT (day after treatment) and 0.88 and 2.02 mg/kg and decreased to 0.43 and 0.98 mg/kg at 36 DAT in field 2, respectively. The half-life of tricyclazole was about 39.6 and 28.1 days for the low and high concentration of tricyclazole treated soils in field 1 and 27.9 and 17.2 days for the low and high concentration of tricyclazole treated soils in field 2, respectively. Residual levels of tricyclazole in Korean cabbage were ranged from 4.03 to 18.26 and from 8.26 to 35.08% of initial concentration in filed 1 and field 2 soils, respectively.

• Korean Chemical Engineering Research
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• v.52 no.1
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• pp.126-132
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• 2014

A pilot-scale electrokinetic (EK) separation field test ($2{\times}3{\times}0.2m^3$, $W{\times}L{\times}D$) was performed in a greenhouse to remove salts from saline soil. Initially, the greenhouse soil had high electrical conductivity (EC), about 9 dS/m, and contained mainly $Ca^{2+}$, $Cl^-$ and $SO_4^{2-}$ ions. After 2 weeks of EK treatment, the soil EC was reduced to 52% compared with its initial value. The EC reduction was mostly achieved within the first week (47%) due to removal of $Na^+$ and $Cl^-$ ions, but ions with a high adsorption capacity such as $Ca^{2+}$ and $SO_4^{2-}$ ions were difficult to be removed. During the EK test, the soil temperature increased and it reached around $50^{\circ}C$ at some regions. For in situ application to soils in cultivation, the current should be controlled to limit increases in temperature, especially near the cathodes. In conclusion, the in situ EK technique is feasible for the restoration of saline greenhouse soils in or no cultivation and an appropriate strategy is necessary for more effective remediation.

• Economic and Environmental Geology
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• v.52 no.1
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• pp.29-35
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• 2019

The purpose of this study was to assess the applicability of acid mine drainage sludge (AMDS) pellets for the arsenic (As) stabilization and to suggest an evaluation method for arsenic stabilization efficiency in soil around abandoned coal mines. The soil samples were collected from the agricultural field around Ham-Tae, Dong-Won, Dong-Hae, and Ok-Dong coal mine. The As concentration in soil was exceeding the criteria of soil pollution level, except for Ham-Tae coal mine. The AMDS pellets are more appropriate to use by reducing dust occurrence during the transport and application process than AMDS powder. In addition, AMDS pellets were maintained the As stabilization efficiency. The application of AMDS pellets for the As stabilization in soil was assessed by column experiments. The AMDS pellets were more effective than limestone and steel slag, which used as the conventional additives for the stabilization process. The As extraction by $0.43M\;HNO_3$ or $1M\;NaH_2PO_4$ solution were appropriate evaluation methods for evaluation of As stabilization efficiency in the soil.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.3
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• pp.234-241
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• 1997

The effects of bulk densities(${\rho}_b$) on saturated hydraulic conductivity (Ksat) and solute elution patterns were investigated from five different bulk densities ranging from $1.1Mg/m^3$ to $1.5Mg/m^3$ with each increment of $0.1Mg/m^3$. The hydraulic conductivities observed were divided into two stages: (1) a linearly decrease with increase in bulk density up to $1.4Mg/m^3$, (2) a steady state where the bulk density is greater than $1.4Mg/m^3$. Using the saturated hydraulic conductivity at the steady state, we figured out the equation describing the correlation between bulk densities(${\rho}_b$) and saturated hydraulic conductivity(Ksat) as follows: $Ksat=-19.2({\rho}_b{^2})+6{\rho}_b+15.5$, (r=0.985). Electrical conductivity(EC) measured from the leachate of the soil column showed that EC at the same pore volume were decreased with an increase in the bulk density from $1.2g/cm^3$, $1.5g/cm^3$, as shown in the time taken to collect the same pore volume at each respective bulk density. The maximum relative concentrations (C/Co=1) from the breakthrough curves for the anions of $Cl^-$, $NO_3{^-}$ and $SO_4{^{2-}}$, which are weakly adsorbed on the soil particles, moved to the right of the graph, while a distinctive retardation occurs at the bulk density between $1.3Mg/m^3$ and $1.4Mg/m^3$. The time taken to recover about 90% of indigenous sulphate was approximately twice as those of chloride and nitrate, resulting in slightly stronger adsorption characteristics for sorption sites on the soil surface. Thus, we can conclude that the salt accumulation in green house soil might be significantly influenced by it's bulk density at the soil depth, as well as the adsorption capacity of ions for the sorption sites in soils.

• Korean Journal of Environmental Agriculture
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• v.36 no.2
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• pp.67-72
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• 2017

BACKGROUND:Cultivation of alternative crops in paddy fields is necessary because of the decrease in rice consumption and the increase in excess stock of rice. The study was conducted to investigate the effects of alternative crops cultivation in paddy fields on soil physico-chemical characteristics and crop yield. METHODS AND RESULTS: Soybean (Glycine max), red-clover (Trifolium pratense), and water convolvulus (Ipomoea aquatica) were selected for alternative crops in the first and/or second year and rice was planted in the third year. When alternative crops were cultivated in the previous year, soil bulk density, soil hardness, and water content were lower than those for rice cultivation. Water-depth decreasing rate and aggregate content were greater for the upland-upland-paddy cropping system than upland-paddy-paddy cropping system. Cultivation of red-clover and water convolvulus for two years resulted in the high soil organic matter content. In the third year, available phosphate, exchangeable potassium, and soil cation exchange capacity were relatively high when soybean was cultivated in the previous year. In the first year, water convolvulus cultivation showed greater productivity than red-clover cultivation while the opposite pattern was found in the second year. Rice yield in the third year was greater for soybean or red-clover as a previous crop than for water convolvulus as a previous crop. CONCLUSION: The results suggest that cultivation of alternative crops in paddy fields can improve soil physical properties including bulk density, hardness, water content, and aggregate content as well as rice productivity.

• Korean Journal of Soil Science and Fertilizer
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• v.34 no.4
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• pp.237-244
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• 2001

Investigation on the surface charge properties of some Korean arable soils was performed by ion adsorption technique with two kinds of indifferent ion ($Na^+$ and $K^+$) at the range of pH 3 to 9 in bulk solution. The contribution of soil components(organic matter, oxides and clay mineral) on the surface charge density was determined at two soil depth with different solid particle composition When the pH of solution increased, the negative charge of soil surface was increased among the all soils, but positive charge were not appeared above pH 6. apparently. The magnitude of surface charge density measured by NaCl adsorption method showed ra nges of $0.01{\sim}2.84cmol_c{\cdot}kg^{-1}$ and $7.41{\sim}12.20cmol_c{\cdot}kg^{-1}$ at pH 3 and pH 9, respectively. Ion adsorption method using KCl as index ion overestimated than the method using NaCl as index ion. The content of organic matter is the strongest factor on the value of dCEC/dpH.

• Journal of Korea Water Resources Association
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• v.50 no.6
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• pp.387-395
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• 2017

Sea level rise, accompanied by climate change, is expected to exacerbate seawater intrusion in the coastal groundwater system. As the salinity of saturated groundwater increases, salinity can increase even in the unsaturated soil above the groundwater surface, which may cause crop damage in the agricultural land. The other adverse impact of sea level rise is reduced unsaturated soil thicknesses. In this study, a composite model to assess impacts of sea level rise in coastal agricultural land is proposed. The composite model is based on the combined applications of a three dimensional model for simulating saltwater intrusion into the groundwater and a vertical one dimensional model for simulating unsaturated zone flow and transport. The water level and salinity distribution of groundwater are calculated using the three dimensional seawater intrusion model. At some uppermost nodes, where salinity are higher than the reference value, of the 3D mesh one dimensional unsaturated zone modeling is conducted along the soil layer between the ground water surface and the ground surface. A particular location is judged salinized when the concentration at the root-zone depth exceeds the tolerable salinity for ordinary crops. The developed model is applied to a hypothetical agricultural reclamation land. IPCC RCP 4.5 and 8.5 scenarios were used as sea level rise data. Results are presented for 2050 and 2100. As a result of the study, it is predicted that by 2100 in the climate change scenario RCP 8.5, there will be 7.8% increase in groundwater saltwater-intruded area, 6.0% increase of salinized soil area, and 1.6% in increase in water-logging area.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.4
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• pp.248-253
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• 1991

This study examines the effect of submergence on transformations of inorganic phosphorus and the relation between fractions of inorganic phosphorus and adsorbed phosphorus in Gangseo (paddy soil), Yesan (non-cultivated soil), and Jungdong soil (upland soil). The soils were submerged with glucose sol'n at $28^{\circ}C$ for 17 days. After, the soils were incubated with phosphate solution at $25^{\circ}C$ for 24 hours. The seguential fractionation of inorganic phosphorus and of iron were conducted to investigate transformations of them. Results obtained are as follows; 1. By submergence, Bray I-P were decreased from 53mgP/kg to 48mgP/kg in Gangseo, from 3mgP/kg to 1mgP/kg in Yesan, and from 120mgP/kg to 56mgP/kg in Jungdong soil. 2. $NH_4F$ extractable P was dominant fraction of adsorbed P. It was transformed into NaOH extractable P by submergence in Jungdong soil. 3. Dithionite-citrate-bicarbonate extractable iron (crystalline Fe) was transformed to oxalate extractable iron (amorphous Fe) by submergence in Yesan soil.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.190-194
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• 2011

경포호 주변환경은 논, 밭 등의 경작지나 녹지와 같은 투수지표면과 대단위 주택단지나 도로, 상업지구, 공장시설과 같은 불투수지표면으로 구성되어 있어 SWAT 모형의 적용에 적합하다. GIS와 연계된 ArcSWAT모형을 적용하기 위하여 지형자료를 구축하고, 송정배수로 유역의 기상 및 우량 관측소를 고려하여 수문 및 기상관측자료를 입력하였다. 그리고, 소유역으로 세분화한 후 토양특성과 토지이용에 따른 모의를 실시하였고, 이를 위해 소유역내 수문학적 반응단위별로 유출, 유사 및 비점오염발생을 평가하는데 이용되는 HRU를 구축하여 활용하였다. 송정배수로는 제1배수로와 제2배수로로 구성되어있으며, 제2배수로의 유입부에 주변 아파트단지의 하수관에서 직접적으로 오염물질이 유입되어 수질오염이 심각하며, 점원과 비점원오염이 산재해있기 때문에 본 연구에서는 유출 및 수질모의가 가능한 SWAT모형을 이용하여 대상지점의 유출과 수질을 모의하였으며, 그 결과를 바탕으로 수질오염을 저감할 수 있는 방안을 제시하였다.