• Korean Journal of Soil Science and Fertilizer
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• v.9 no.1
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• pp.9-16
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• 1976

In order to investigate inherent erodibility of the soil, which is a major factor is soil erosion prediction, a survey on runoff and soil loss of reclaimed upland soil was carried out by using a portable rainulator. The relations of soil loss and some physical properties of the soil were discussed. The soil erodibility factor for Universal soil loss equation was calculated and compared with that of Wischmeier's nomograph. The result were as follows: 1. Total runoff increased for finer textured soil in order of Jeonnam silty clay loam, Songjeong clay loam, Yesan loam, Samgag and Sangju sandy loam. Total soil loss and soil content in runoff were not correspondently related with textural characteristic in order of Jeonnam, Samgag, Sangju, Yesan, and Songjeong. Total runoff, soil loss, and soil content in runoff were increased for steeper slope. 2. Soil loss and soil content in runoff negatively correlated with organic matter content of surface soil, while positively correlated with dispersion ratio, clay ratio, silt content, and significantly correlated with Middleton erosion ratio for coarser textured soil but not correctly related for finer textured soil. 3. The soil erodibilty factor K values for Universal soil loss equation were 0.32 for Jeonnam, 0.22 for Samgag, 0.17 for Sangju, 0.15 for Yesan, and 0.13 for Songjeong respectively. These values were close to those from Wischmeier's nomograph. So, it seems that the nomograph is useful for estimation of soil loss in Korea.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.301-305
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• 2012

The amount of irrigation water can be calculated based on the irrigation schedule in irrigation manual. At present, the maximum irrigation manual, which was developed in 1999 for the maximum yield with maxmum irrigation, is using. Now the water saving irrigation manual for red pepper, without decrease of crop yield, has been developded in 45 areas of korea. Among 45 regions, 9 regions which were selected respectively from 9 Provinces of Korea, were used for this study. The water saving irrigation manual has been used easily without soil sampling and measurement of soil water status. The objective of this study is to assess the possibility of the saving of irrigation water compared to the maximum irrigation manual. The average potential evapo-transpiration (PET) during 30 years in 9 region for the red pepper cultivation was a $2.69mm\;day^{-1}$. The saving amount of irrigation water for red pepper cultivation by saving irrigation manual compared to the maximum irrigation manual in a year was 309.4 mm, 303.3 mm and 309.5 mm in the soil of Sandy Loam (SL), Loam (L) and Silty Loam (SiL), respectively. The average saving amount of irrigation water for red pepper cultivation by saving irrigation manual compared to the maximum irrigation manual in a year was 307.4 mm.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.3
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• pp.399-403
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• 2012

The management of heavy metals in soil is important for environmental-friendly agriculture and keeping an ecosystem healthy. In this study, we examined the concentrations of heavy metals (Cd, Cr, Cu, Ni, Pb, Zn, and As) in 260 paddy soils sampled from Gyeongnam Province. The concentrations of the heavy metals were 0.143 mg $kg^{-1}$ (ranged 0.003-0.537) for Cd, 0.322 (0.002-0.986) mg $kg^{-1}$ for Cr, 25.41 (6.03-76.19) mg $kg^{-1}$ for Cu, 16.36 (2.63-32.94) mg $kg^{-1}$ for Ni, 18.67 (4.16-87.02) mg $kg^{-1}$ for Pb, 71.76 (22.99-153.58) mg $kg^{-1}$ for Zn, and 3.516 (0.002-19.481) mg $kg^{-1}$ for As, respectively. In addition, the concentration of Cd was highest in mountain foot-slope, Ni and As were highest in diluvial terrace, and Zn was highest in marine plains. Higher concentrations of Cd, Cu, and Zn were found in silty clay loam soils compared to silt loam, sandy loam, and loam soils.

• Korean Journal of Environment and Ecology
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• v.28 no.3
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• pp.331-341
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• 2014

The present study was to survey the site environment, vegetation structure and soil characteristics in the wild habitats of Wikstroemia ganpi in Goheung, Busan and Ulsan, and offers basic information for habitat conservation and restoration. Most of the wild habitats were located at altitudes between 28~242m with inclinations ranged as $0{\sim}40^{\circ}$. The canopy openness was 57.56%. The vegetation structure by the PC-ORD based on the Two Way Cluster Analysis were divided into three groups Community I(Castanea crenata-Pinus densiflora), Community II(Quercus dentata-Pinus thunbergii) and Community III (Pinus thunbergii). The species diversity was 1.3650, and evenness and dominance were found recorded as 0.8666 and 0.1333, respectively. The soil textures were silty loam and sandy loam. The average soil pH was 5.5, electric conductivity was 0.15dS/m, soil organic matter was 2.60% and available phosphorus was 4mg $kg^{-1}$. Correlation coefficients based on environmental factors, vegetation and soil analysis were showed that positive correlations between species diversity and evenness, organic matter and total nitrogen, whereas species slop degree and coverage of herb, diversity and dominance were showed negative correlations.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.4
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• pp.309-313
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• 1997

Field experiments were conducted on Jeonbug series (Fine silty, mesic family of Aeric Fluventic Haplaquepts), to study the effect of split application of N fertilizer in combination with rice straw on N use efficiency of dry-soil-direct seeded paddy rice. Treatments involved conventional application of N (in three splits; 40% at planting, 30% at five leaf stage and at heading stage) without rice straw, all basal application of N with straw application (5000 kg/ha), N application in two splits (70% at planting and 30% at heading stage) with rice straw application and N application in three splits (40% at planting, 30% at five leaf stage, 30% at heading stage) with application of rice straw. There was Zero N plot too for the estimation of N use efficiency. Seeding was done on dry soil and the filed was flooded 32 days after seeding. The fertilizer application rates were 160, 70, and 80 kg/ha of N, $P_2O_5$ and $K_2O$, respectively. The experiment was conducted for two years, in the same filed. The apparent use efficiency of fertilizer N by rice tended to be higher under the application of rice straw when N was applied in three splits. This, however, did not increase the yield of rice significantly. Even under the application of rice straw, the apparent N use efficiency was lower when N fertilizer was applied in one dose at the planting and in two splits. The lower N use efficiency in these cases, did not yield of rice significantly. The periodical analysis of mineral N in the soil suggested that higher mineral N in the soil at the early stages was responsible for the lower apparent N use efficiency.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.65-74
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• 2003

Most of land reclamation projects are being implemented along the south and west coastal lines of the Korean Peninsula. The earth structures and in-ground LNG tank, and buildings can be constructed using artificial freezing method on the reclaimed land to control the uplift pressure caused by capillary forces. In this study, upon freezing a saturated soil in a closed-system from the top, a considerable frost heaving pressure was developed. Decomposed granite soils, silty soil, and sandy soil were used in the laboratory freeze test which is sometimes subjected to thermal gradients under closed-systems. A major concern has been the ability to predict the frost heaving pressure over the results of relatively short-term laboratory tests. The frost heaving pressure arising within the soil samples and the temperature of the samples inside were monitored with time elapse. The degree of saturation versus heaving pressure curve is presented for each soil sample and the maximum pressure is closely related to this curve. TDR apparatus was used to measure the volumetric water content by the measurement of unfrozen water contents of frozen soils. Unfrozen water increased in soils containing a high percentage of fine-grained particles. In fine-grained soils with strong attractive farces between soil grains and water molecules, additional water is attracted into the pores leading to further volume changes and ice segregation.

• Journal of the Korean GEO-environmental Society
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• v.9 no.2
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• pp.39-46
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• 2008

Due to the growth in industrialization, potential hazards in subsurface environments are becoming increasingly significant. The extraction of the contaminant from the soil and movement of the water are restricted due to the low permeability and adsorption characteristics of the reclaimed soils. There are a number of approaches to in-situ remediation that are used in contaminated sites for removing contaminants. These include soil flushing, dual phase extraction, and soil vapor extraction. Among these techniques, soil flushing was the focus of the investigation in this paper. Incorporated technique with PVDs has been used for dewatering from fine-grained soils for the purpose of ground improvement by means of prefabricated vertical drain systems. The laboratory model tests were performed by using the flushing tracer solutions for silty soils and recorded the tracer concentration changes with the elapsed time and flow rates. The modeling was intended to predict the effectiveness and time dependence of the remediation process. Modeling has been performed on the extraction, considering tracer concentration and laboratory model test characteristics. The computer model used herein are SEEP/W and CTRAN/W, this 2-D finite element program allows for modeling to determine hydraulic head and pore water pressure distribution, efficiency of remediation for the subsurface environment. It is concluded that the coefficient of permeability of contaminated soil is related with vertical velocity and extracted flow rate. The vertical velocity and extracted flow rate have an effect on dispersivity and finally are played an important role in-situ soil remediation.

• Journal of the Korean Geotechnical Society
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• v.22 no.9
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• pp.61-68
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• 2006

Recently the large scale civil engineering projects are being implemented by reclaiming the sea or utilizing seashore and river embankment areas. The reclaimed land and utilized seashore are mostly soft ground that doesn't have sufficient bearing capacity. This soft ground consists of fine-grained soil such as clayey and silty soils or large void soil like peat or loose sand. It has high ground water table and it may cause the failure and crock of building foundation by uplift pressure and ground water leakage. In this study, the permittivity and the transmissivity were evaluated with the applied normal pressure in the laboratory. The laboratory model tests were conducted by utilizing geocomposite drainage system for draining the water out to release the uplift pressure. The soil used in the laboratory drainage test was dredged soil from the reclaimed land where uplift pressure problems can arise in soil condition. Geocomposite drainage system was installed at the bottom of apparatus and dredged soil was layered with compaction. Subsequently the water pressure was supplied from the top of specimen and the quantities of drainage and the pore water pressure were measured at each step water pressure. The results of laboratory measurements were compared with theoretical values. For the evaluation of propriety of laboratory drainage test, 2-D finite elements analysis that can analyze the distribution and the transferring of pore water pressure was conducted and compared with laboratory test results.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.3
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• pp.334-339
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• 1985

A sweet corn hybrid, Honey Bantam, was planted on 24 May, 1984 in a silty clay loam soil to investigate the effects of polyethylene(P.E.) mulch and different levels and placements of Nitrogen(N) on soil properties and sweet corn growth. A split-split plot design with three replications was employed; P.E. mulch and bare soil were main plot, N levele of 8, 12, 16, and 20 kg/10a were subplot, and band and broadcast of fertilizers were sub-subplots. At early growth stage soil temperature under P.E. mulch was higher than that in bare soil by 5-10$^{\circ}C$, but the differences decreased as plant growth advanced. Soil hardness increased with soil depth while P.E. mulch reduced soil hardness probably by holding high soil moisture. Soil pH decreased up to the 6th week after planting and then increased in bare soil, but it contineously decreased up to the 8th weeks under P.E. mulch regardless N levels and placements. Electrical conductivity(EC) of soil increased up to the 6th weeks after planting and then decreased in all treatments except broadcast of fertilizers under P.E. mulch where EC increased contineously. Generally, soil EC under P.E. mulch was higher than that in broadcast. Broadcast of fertilizers did not affect emergence of seedlings in all N levels under P.E. mulch and bare soil, but band of fertilizers at all N levels under P.E. mulch and higher levels of N in bare soil reduced emergence rate significantly. Percent stand was possitively correlated with soil EC and it strongly influenced the number of marketable ears. Plant growth was enhanced and silking date was earlier by 14-19 days under P.E. mulch compared to bare soil probably due to increased soil moisture, reduced soil hardness and higher soil temperature.

• Korean Journal of Soil Science and Fertilizer
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• v.11 no.3
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• pp.145-160
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• 1979

The effects of organic material application on soil physical properties were reviewed in relation to soil productivity. The organic matter contents and soil physical properties of the cultivated land in Korea were summarized and the effects of organic matter were compared in terms of land uses and soil types. Soil physical properties related to crop yield potential, such as soil aggregation, permeability, water holding capacity, erodibility, and compactibility, were used in evaluating the effects of organic materials as a soil physical amendment. The benefical effects of organic matter addition on soil physical conditions include (1) better aeration and increased infiltration in silty and clayey soils, (2) increased water holding capacity and moisture availability in sandy soils, (3) decreased soil erodibility, and (4) increased resistance to compaction. It is, therefore, concluded that continuous application of organic materials could greatly improve the various soil physical properties and favor the growth and yield of crops. A high rate of organic matter addition could contribute to reducing not only the soil erosion on sloping land, but also the possible detrimental effect of farm mechanization. In general, the effects of organic matter on soil physical improvement were estimated to be much higher in upland than in paddy. Organic matter would have a more pronounced effect on low productive lands such as heavy clayey or sandy soils and newly reclaimed soil. The optimum level of soil organic matter content was estimated to be about 3.0 to 3.5% for the best soil physical condition. Since the organic matter contents of the cultivated lands in Korea are much lower than optimum level, it would be desiable to use more organic materials to soil for the increase of soil productivity, continuation of stabilized high productivity and soil erosion control.