• 한국토양비료학회지
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• 제46권6호
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• pp.474-481
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• 2013

Understanding the microbial community structure of agricultural soils is important for better soil management in order to improve soil quality. Phospholipid fatty acid analysis has been popularly used in determining the microbial community structure in different ecosystems. The microbial community structure of paddy soil under long-term fertilizer treatments was investigated after 45 years using PLFA analysis. Treatments were control (no fertilization, Con), compost (COM), NPK, NPK+compost (NPKC), PK, NK, and NP. Soil chemical properties were mainly affected by the addition of compost and inorganic P fertilizer. Total nitrogen and organic matter contents were significantly higher in treatments with compost while available $P_2O_5$ and exchangeable calcium were significantly higher in treatments with added inorganic P fertilizer. It was found that microbial communities were responsive to the different fertilizer treatments. PLFA results showed that the soils were dominated by gram-negative bacteria, followed by the actinomycetes, then gram-positive bacteria, and fungi. Principal component analysis of the soil chemical properties and PLFA composition proved to be a more reliable tool because it was more responsive to the changes in soil chemical properties.

• Geomechanics and Engineering
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• 제28권6호
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• pp.559-571
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• 2022

Deep soil mixing, DSM technique has been widely used to improve the engineering properties of problematic soils. Due to growing urbanization and the industrial developments, disposal of brick dust poses a big problem and causes environmental problems. This study aims to use brick dust in DSM application in order to minimize the waste in brick industry and to evaluate its effect on the improvement of the geotechnical properties. Three different percentages of cement content: (10, 15 and 20%) were used in the formation of soil-cement mixture. Unlike the other studies in the literature, various percentages of waste brick dust: (10, 20 and 30%) were used as partial replacement of cement in soil-cement mixture. The results indicated that addition of waste brick dust into soil-cement mixture had positive effect on the inherent strength and stiffness of loose sand. Cement replaced by 20% of brick dust gave the best results and reduced the final setting time of cement and resulted in an increase in unconfined compressive strength, modulus of elasticity and resilient modulus of sand mixed with cement and brick dust. The findings were also supported by the microscopic images of the specimens with different percentages of waste brick dust and it was observed that waste brick dust caused an increase in the interlocking between the particles and resulted in an increase in soil strength. Using waste brick dust as a replacement material seems to be promising for improving the geotechnical properties of loose sand.

• Earthquakes and Structures
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• 제22권3호
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• pp.219-230
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• 2022

Knowing that the variability of soil properties is an important source of uncertainty in geotechnical analyses, we will study in this paper the effect of this variability on the seismic response of a structure within the framework of Soil Structure Interaction (SSI). We use the proposed and developed model (N2-ISS, Mekki et al., 2014). This approach is based on an extension of the N2 method by determining the capacity curve of the fixed base system oscillating mainly in the first mode, then modified to obtain the capacity curve of the system on a flexible basis using the concept of the equivalent nonlinear oscillator. The properties of the soil that we are interested in this paper will be the shear wave velocity and the soil damping. These parameters will be modeled at first, as independent random fields, then, the two parameters will be correlated. The results obtained showed the importance of the use of random field in the study of SSI systems. The variability of soil damping and shear wave velocity introduces significant uncertainty not only in the evaluation of the damping of the soil-structure system but also in the estimation of the displacement of the structure and the base-shear force.

• Geomechanics and Engineering
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• 제28권1호
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• pp.35-48
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• 2022

The effect of discrete polypropylene fibre reinforcement on shear strength parameters, tensile properties and isotropic index of stabilized compacted residual subgrade was investigated. Composites of compacted subgrade were developed from polypropylene fibre dosage of 0%, 1%, 2.5% and 4% and 3% cement binder. Saturated compacted soil benefited from incremental fibre dosage, the mobilized friction coefficient increased to a maximum at 2.5% fibre dosage from 0.41 to 0.58 and the contribution due to further increase in fibre dosage was marginal. Binder stabilization increased the degree of isotropy for unreinforced soil at lower fibre dosage of 1% and then decreased with higher fibre dosage. Saturation of 3% binder stabilized soil decreased the soil friction angle and the degree of isotropy for both unstabilized and binder stabilized soil increased with fibre dosage. The maximum tensile stress of 3% binder stabilized fibre reinforced residual soil was 3-fold that of 3% binder stabilized unreinforced soil. The difference in computed and measured maximum tensile and tangential stress decreased with increase in fibre dosage and degree of stabilization and polypropylene fibre reinforced soil met local and international criteria for road construction subgrade.

• Structural Engineering and Mechanics
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• 제10권4호
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• pp.299-312
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• 2000

The response of an embedded body to dynamic loads is greatly influenced by the reactions of the soil to the motion of the body. The properties of the soil surrounding embedded bodies (e.g., piles) may be different than those of the far-field for a variety of reasons. It may be weakened or strengthened according to the method of installation of piles, or altered due to applying one of the soil strengthening technique (e.g., electrokinetic treatment of soil, El Naggar et al. 1998). In all these cases, the shear strength of the soils and its shear modulus vary gradually in the radial direction, resulting in a radially inhomogeneous soil layer. This paper describes an analysis to compute vertical and torsional dynamic soil reactions of a radially inhomogeneous soil layer with a circular hole. These soil reactions could then be used to model the soil resistance in the analysis of the pile vibration under dynamic loads. The soil layer is considered to have a piecewise, radial variation for the complex shear modulus. The model is developed for soil layers improved using the electrokinetic technique but can be used for other situations where the soil properties vary gradually in the radial direction (strengthened or weakened). The soil reactions (impedance functions) are evaluated over a wide range of parameters and compared with those obtained from other solutions. A parametric study was performed to examine the effect of different soil improvement parameters on vertical and torsional impedance functions of the soil. The effect of the increase in the shear modulus and the width of the improved zone is investigated.

• 아시안잔디학회지
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• 제23권2호
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• pp.271-278
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• 2009

본 연구는 골프장의 상토조성 시 사용되는 토양개량제의 적절한 활용과 이해를 위해 입경과 화학적 특성이 비슷한 무기성 토양개량제의 3종의 혼합비율에 따른 모래상토의 물리 화학적 특성변화를 조사하였다. 토양개량제의 혼합비율에 따라 상토의 물리 화학성을 조사한 결과는 다음과 같다. A와 C가 pH가 95% 수준에서 상관성을 나타내었고, C의 양이온치환용량이 95% 수준에서 상관성을 보여 토양개량제의 특성에 따라 상토의 토양화학성에 영향을 주었다. 상토의 토양물리성 결과를 통해 USGA 기준으로 평가할 때, 최적의 혼합비율은 토양개량제 A와 B에서는 3%였고, C는 7~10% 였다. 각 토양개량제들의 혼합에 따른 토양물리성변화에 가장 큰 영향을 미치는 물리적 요인은 총공극량이었다. 토양개량제의 혼합비율에 따른 토양개선효과 를 비교할 때, B는 모세관공극과 비모세관공극에서, C는 모세관공극, 총공극 및 수리전도 도에서 고도의 상관성을 나타내었다(P<0.05). 이들 결과를 통해 골프코스의 상토조성에 사용되는 무기성 토양개량제는 그 종류와 혼합비율이 USGA 상토의 뿌리층 개량의 토양 이화학성에 영향을 미치고 있음을 알 수 있었다.

• 한국토양비료학회지
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• 제42권3호
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• pp.187-191
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• 2009

'Campbell Early', a major grape cultivar, occupies more than 70% of cultivated vineyard areas, however, recommendable standard management system of soil environmental conditions has not been developed yet in Korea. The consideration for the correlation between fruit quality and soil condition in the vineyard is required in the efficient management system of soil. This study was carried out to investigate the optimum soil environmental conditions for 'Campbell Early' grape production with high quality. The results from analyses of correlation between them were used to develop soil management guideline for promoting efficiency in grape production. Soil properties were analyzed from 120 vineyards in Hawsung, Sangju, Yeongdong, Gimcheon, Yeongju, and Yeongwol, major grape production regions. Because there is neither coloring disorder nor delayed coloration in grape production of 'Campbell Early', relative contribution of soil hardness and solid phase to fruit quality and fruit weight was analyzed. Among the soil properties, while cation and soil hardness affected sugar content at the level of 39.3% and 36.8%, respectively, saturated hydraulic conductivity, solid phase, and cation exchange capacity (CEC) showed relatively low contribution to sugar content in the vineyard. The sugar content in grapes was influenced more critically by the chemical properties than the physical ones in the soil of vineyards. While soil hardness and solid phase affected grape weight at the level of 27.8% and 26.0%, respectively, phosphate content, organic matter content, and cation showed low contribution to grape weight. Grape guality such as sugar content and grape weight was affected highly by cation and organic matters. Therefore, cation and organic matter content of soil contributed to fruit quality at the level of 33.8% and 15.5%, respectively, in the vineyard.

• 한국환경생태학회지
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• 제22권3호
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• pp.260-267
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• 2008

본 연구는 경남 산림지역의 산성강하물과 토양 화학적 특성의 관련성 조사를 위하여 수행하였다. 토양 pH는 평균 4.40이었으며, 가장 높은 조사구는 밀양 산내 조사구로 pH 5.02였고, 가장 낮은 조사구는 pH 4.08의 남해 서면이었다(p<0.05). 산림토양내 유기물, 유효인산, 칼륨, 칼슘, 마그네슘, 양이온치환용량(CEC)은 지역별 유의차가 있었다(p<0.05). 산림토양내 중금속 함량은 납이 평균 3.86mg/kg이었고, 거제 신현이 9.87mg/kg으로 가장 높았으며, 밀양 산내가 0.86mg/kg으로 가장 낮았다(p<0.05). 토양의 화학적 특성과 강우산도의 상관은 토양 $pH(r=0.7826^{**})$, 칼슘 $(r=0.6278^*)$, 마그네슘$(r=0.5841^*)$, 양이온치환용량$(r=0.6341^{**})$, 카드뮴$(r=0.5995^*)$과 정의 상관이었고, 납$(r=-0.5283^*)$은 부의 상관이었다. 대기 중의 $SO_2$, 농도와 상관은 토양 pH$(r=-0.6796^{**})$, 칼슘$(r=-0.5810^*)$, 마그네슘$(r=-0.5522^*)$, 양이온치환용량$(r=-0.5905^*)$과 부의 상관이었다. 대기 중의 $NO_2$, 농도와 상관은 유기물$(r=0.6208^*)$, 칼륨$(r=0.5380^*)$과 정의 상관이었다. 따라서 강우산도 및 대기 중의 $SO_2$는 토양의 산성화에 영향을 미치는 것으로 사료되며, 그리고 토양 내 중금속 함량에 영향을 미치는 것은 Cd와 Pb함량과 관련성이 있으며, 그 외 중금속의 영향은 없었다.

• 한국토양비료학회지
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• 제50권1호
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• pp.65-70
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• 2017

Soil was regarded as infinite resources but recently, soil is considered as invaluable resources that we need to protect and conserve. Main objective of this research was to evaluate soil value in terms of soil carbon contents. Soil was classified into forest, paddy, upland, and grass. Carbon contents in each soil was calculated based on soil chemical properties. Calculated soil carbon contents was ranged $15.31-108.86mg\;kg^{-1}$. Based on soil carbon contents, soil value was assumed adapting economic concepts. Calculated total soil value based on soil carbon contents was about 18.46 trillion won. Among others, carbon contents in forest was the highest and value was assumed 11.95 trillion won followed by paddy field (3.7 trillion won).

• 한국토양비료학회지
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• 제34권4호
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• pp.278-283
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• 2001

근적외 이용 토양분석기에 의한 토양수분, 유기물, 전질소 측정과 그 외 토양의 여러 가지 이화학 성분에 대한 측정결과를 검토하였다. 토양시료를 몰탈로 갈아서 토양입자를 0.2mm의 체를 통과시킨 140점의 토양시료를 85점은 근적외 토양분석기의 표준곡선을 작성하고 나머지 55점의 토양시료는 표준곡선을 이용하여 추정한 토양의 이화학성 중에서 토양수분, 토양 pH, 유기물, 전질소 CEC, 치환성 Ca, Mg, K 및 유효규산함량은 근적외 토양분석기로 동시에 추정할 수 있어 시비처방을 위한 토양의 비옥도를 판정하는데 유용하게 이용할 수 있을것으로 생각된다.