• Journal of the Korean Society of Industry Convergence
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• v.20 no.5
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• pp.395-404
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• 2017

Cultivating soybeans in rice paddy field reduces labor costs and increases the yield. Soybeans, however, are highly susceptible to excessive soil water in paddy field. Controlled drainage system can adjust groundwater level (GWL) and control soil moisture content, resulting in improvement soil environments for optimum crop growth. The objective of this study was to fit the soybean growth data (canopy height and stem diameter) using Gompertz model and Logistic model at different GWL and validate those models. The soybean, Daewon cultivar, was grown on the lysimeters controlled GWL (20cm and 40cm). The soil textures were silt loam and sandy loam. The canopy height and stem diameter were measured from the 20th days after seeding until harvest. The Gompertz and Logistic models were fitted with the growth data and each growth rate and maximum growth value was estimated. At the canopy height, the $R_2$ and RMSE were 0.99 and 1.58 in Gompertz model and 0.99 and 1.33 in Logistic model, respectively. The large discrepancy was shown in full maturity stage (R8), where plants have shed substantial amount of leaves. Regardless of soil texture, the maximum growth values at 40cm GWL were greater than the value at 20cm GWL. The growth rates were larger at silt loam. At the stem diameter, the $R_2$ and RMSE were 0.96 and 0.27 in Gompertz model and 0.96 and 0.26 in Logistic model, respectively. Unlike the canopy height, the stem diameter in R8 stage didn't decrease significantly. At both GWLs, the maximum growth values and the growth rates at silt loam were all larger than the values at sandy loam. In conclusion, Gompertz model and Logistic model both well fit the canopy heights and stem diameters of soybeans. These growth models can provide invaluable information for the development of precision water management system.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.4
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• pp.240-245
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• 2015

The monitoring of soil fertility changes in orchard is very important for agricultural sustainability. Field monitoring was performed to evaluate the soil chemical properties of 140 orchard (23 sites for sandy loam, 88 sites for loam, 28 sites for silt loam, and 1 site for loamy fine sand) in Gyeongnam province every 4 years from 2002 to 2014. Soil chemical properties such as pH, electrical conductivity, amount of organic matter (OM), available phosphate ($P_2O_5$), lime requirement (LR), exchangeable potassium (K), calcium (Ca), magnesium (Mg), and sodium were analyzed. The amount of OM, exchangeable K, Ca, and Mg were significantly increased as cultivation year increases. The frequency distribution within optimum range of subsoil chemical properties in 2014 was 34.3% for pH, 35.0% for OM, 17.1% for available $P_2O_5$, 22.9% for exchangeable K, 15.7% for exchangeable Ca, and 22.1% for exchangeable Mg. In addition, the available $P_2O_5$ and exchangeable calcium were excess level with portions of 69.3% and 48.6%, respectively. The soil chemical properties in the topsoil and subsoil showed that soil pH was significantly higher in sandy loam soil than those from the loam and silt loam soils. The OM, exchangeable K, Mg, and LR of loam soil were higher than those from the sandy loam soil. These results indicated that a balanced management of soil chemical properties as affected by soil texture can improve the amount of fertilizer applied for sustainable agriculture in orchard field.

• Journal of Environmental Science International
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• v.4 no.5
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• pp.41-41
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• 1995

In order to discuss the differences among the SMP(Surface Moisture Availability Parameter), by previous researchers on the basis of their own theoretical and empirical background, we assessed the SMP according to the soil types and volumetric soil water contents. The results are as follows. There are differences among all the five SMAPs. There''s a tendency that the larger grain size, the higher value of parameters. And they divided into two groups for their value: one group has parameters with exponential function and the other with cosine and linear function. The maximum difference between the two groups appears when the volumetric soil water contents are 0.07$m^3m^{-3}$ for sand, 0.l1$m^3m^{-3}$ for loam, 0.12 for clay, and 0.13$m^3m^{-3}$ for silt loam. So, these differences must be considered when we estimate the surface evaporation rate. From field data, the paddy field soil around Junam reservoir is classified as a silt has high wetness, 0.56. So, the parameter obtained from the field measurement is much higher than that of Clapp and Hornberger(1978)''s Table. This study treated the SMP for a certain point of time in winter season. But if we measured the soil water contents continuously, we could obtain better time-dependent parameter.

• Journal of Environmental Science International
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• v.4 no.5
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• pp.427-435
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• 1995

In order to discuss the differences among the SMP(Surface Moisture Availability Parameter), by previous researchers on the basis of their own theoretical and empirical background, we assessed the SMP according to the soil types and volumetric soil water contents. The results are as follows. There are differences among all the five SMAPs. There's a tendency that the larger grain size, the higher value of parameters. And they divided into two groups for their value: one group has parameters with exponential function and the other with cosine and linear function. The maximum difference between the two groups appears when the volumetric soil water contents are 0.07m3m-3 for sand, 0.l1m3m-3 for loam, 0.12 for clay, and 0.13m3m-3 for silt loam. So, these differences must be considered when we estimate the surface evaporation rate. From field data, the paddy field soil around Junam reservoir is classified as a silt has high wetness, 0.56. So, the parameter obtained from the field measurement is much higher than that of Clapp and Hornberger(1978)'s Table. This study treated the SMP for a certain point of time in winter season. But if we measured the soil water contents continuously, we could obtain better time-dependent parameter. Key words : SMAP(Surface Moisture Availability Parameter), Paddy field, Volumetric soil water content, Evaporation, Capillary potential.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.5
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• pp.231-237
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• 2005

Gypsum treated to fine sandy loam increased the fornation of >2 mm aggregates in $1,550kg\;CaSO_4{\cdot}2H_2O\;10a^{-1}$ (Kbfg1) and $3,100kg\;CaSO_4{\cdot}2H_2O\;10a^{-1}$ (Kbfg2) to compare with control, Kc, at 60DAT, and bigger aggregates in general at 90DAT. The higher treatment of gypsum level, the <0.1 mm aggregates were less decreased as in Kbfg1, Kbfg2, and $6,200kg\;CaSO_4{\cdot}2H_2O\;10a^{-1}$ (Kbfg3) and aggregates of 0.25->2 mm were increased with increasing level of gypsum with more effective in Kbfg2 and Kbfg3 at 120DAT. Gypsum treated to silt loam increased aggregates of 2.0-1.0 and 1.0-0.5 mm in $3,100kg\;CaSO_4{\cdot}2H_2O\;10a^{-1}$ (Mbfg2) to compare with control (Mc), at 60DAT. Degrees of aggregation from 0.5-0.25 mm to >2 mm aggregates at 90DAT were distinctly higher. The higher treatment of gypsum level accelerated more aggregation of silt loam soil, and aggregates of 0.5-0.25 mm was most increased in Mbfg2 at 120DAT. Popped rice hulls treated to fine sandy loam increased aggregates of 2.0-1.0 mm in plots of $1,000kg\;10a^{-1}$ (Kbfhl) only to compare with control (Kc), at 60DAT, and aggregates of >2 mm and 2.0-1.0 mm Kbfh1 at 90DAT. At 120DAT, aggregation by popped rice hulls was most effective in Kbfbl pot. Popped rice hulls treated to silt loam increased in aggregates of >2 mm and 2.0-1.0 mm in $2000kg\;10a^{-1}$, Mbfb2 to compare with control, Mc, at 60DAT. Degrees of aggregation by popped rice hulls at 90DAT were higher in $1,000kg\;10a^{-1}$, Mbfh1, and Mbfh2, and at 120DAT was in $3,000kg\;10a^{-1}$, Mbfb3. Zeolite treatment with popped rice hulls, $1,500kg\;10a^{-1}$, increased in >2.0 mm aggregates in $1,000kg\;10a^{-1}$, Kbfbz1, $2,000kg\;10a^{-1}$, Kbfbz2, $3,000kg\;10a^{-1}$, Kbfhz3, and Mbfbz1, $1,000kg\;10a^{-1}$, Mbfbz2, $2,000kg\;10a^{-1}$, and $3,000kg\;10a^{-1}$, Mbthz3, to compare with control (Kc and Mc), at 60DAT. irrespective of soil texture. At 90DAT, >2.0-0.5 mm aggregates increased in Kbfhz1 of fine sandy loam. aggregates of >0.25 mm in $200kg\;10a^{-1}$ (Mbfbz1), $400kg\;10a^{-1}$ (Mbfhz2), $800kg\;10a^{-1}$ (Mbfhz3) of silt loam increased with the level of zeolite treatment. At 120DAT, the effect of zeolite treated to both soils showed the decrease of <0.1 mm aggregates. As the result, soil amendments for soil aggregation was more effective in the order of popped rice hulls+Zeolite > gypsum > popped rice hulls in fine sandy loam, and in the order of gypsum > popped rice huUs+zeolite > popped rice hulls in silt loam, respectively.

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.1
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• pp.87-95
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• 2002

This study was carried out to investigate the load of soil layers affected by soil depth in artificial soil alone or in blends with Loam with various ratio. The artificial soils were perlite large grain, perlite small grain, and perlite small grains blended with Loam (sand 46%, silt 40%, clay 14%) at a ratio of 8:2, 6:4, 5:5 (v/v). The soil layers were divided into a planting layer and a well-drained layer, then the weight of each layer in the air-dried state and in the field capacity were determined. The data were subjected to correlation analysis, regression analysis, and paired samples t-test. The summarized results are as follows; 1) In the air-dried state, the regression equations of the well-drained layer weight(kg/m2) in perlite large grain, planting layer weight in perlite small grain, planting layer weight in perlite small grain biended with loam(8:2, v/v), perlite small grain blended with loam(6:4, v/v), and perlite small grain blended with loam(5:5, v/v) were; 1.65824*X+0.026, 1.52292*X-0.052, 3.21468*X+0.515, 6.17549*X+ 0.083, and 6.02100*X + 33.133, respectively, where X is soil depth measured in Centimeters. 2) In the field capacity, the regression equations of the well-drained layer weight(kg/m2) in perlite large grain, planting layer weight in perlite small grain, planting layer weight in perlite small grain blended with loam(8:2, v/v), perlite small grain blended with loam(6:4, v/v), and perlite small grain blended with loam(5:5, v/v) were 5.055*X - 2.006, 7.073*X + 100.008, 8.092*X + 116.676, 10.766*X + 100.112, and 10.974*X + 124.423, respectively, where X is the soil depth measured in Centimeters. 3) All of the equations mentioned above were statistically reliable and therefore easily applicable in practical business affairs.

• Journal of the Mineralogical Society of Korea
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• v.19 no.4 s.50
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• pp.355-361
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• 2006

Artificially crushed sands occupy approximately 30 percent of the total consumption in South Korea. The demand for the crushed sands is expected to rise in the future. Most manufacturers use granitic rocks to produce the crushed sands. During the manufacturing process, fine fractions (i.e., sludges or particles smaller than 63 microns) are removed through the process of flocculation. The fine fraction occupies about 15% of the total weight. The sludges are comprised of quartz, feldspars, calcite, and various kinds of clay minerals. Non-clay minerals occupy more than 75 percent of the sluges weight, according to the XRD semi-quantification measurement. Micas, kaolinites, chlorite, vermiculite, and smectites occur as minor constituents. The sludges from Jurassic granites contain more kaolinites and $14{\AA}$-types than those from the Cretaceous ones. The chemical analysis clearly shows the difference between the parent rocks and the sludges in chemical compositions. Much of colored components in the sludges was accumulated as the weathering products. Particle size analysis results show that the sludges can be categorized as silt loam in a sand-silt-clay triangular diagram. This result was for her confirmed by the hydraulic conductivity data. In South Korea, the sludges remained after crushed sand production are classified as an industrial waste because of their impermeability, and which is caused by their high silt and clay fractions.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.2
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• pp.41-50
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• 2013

We investigated influence of continuous application of gypsum(G:$CaSO_4{\cdot}2H_2O$), popped rice hulls(H) and zeolite(Z) on soil aggregation of reclaimed silt loam soils. The application rates amended to silt loam from reclaimed soils at Saemangeum of Mangyeong were varied as follows; 1550(G1), 3100(G2), 6200 (G3) gypsum kg/10a, 1000(H1), 2000(H2), 3000(H3) popped rice hulls kg/10a, and 200(HZ1), 400(HZ2), 800(HZ3) zeolite kg/10a added to 1500 popped rice hulls kg/10a, respectively. In addition, the bermuda grass was growing, and the soil aggregates were analyzed for 60, 90 and 120 days after treatments(DAT). At 60 DAT, the effect of treatment was in order of G>H${\geq}HZ$, and the 1550kg/10a(G1) was the highest as 52.48%. At 90 DAT, the effect of treatment was also in order of G>H>HZ. Those was 3.78-3.12, 2.03-3.03 and 1.79-2.57 times in compared with the control, respectively. At 120 DAT, the effect of treatment was similar continued in order of G>H>HZ. Those was 3.00-2.20, 1.06-1.64 and 0.92-1.23 times in compared with the control, respectively. In conclusion, we found that the continuous application for two year of gypsum, popped rice hulls and zeolite was excellent above the 1 year, and the effect of the treatment for soil amendments of reclaimed silt loam soil was excellent in order of G>H>HZ.

• Journal of Ecology and Environment
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• v.32 no.4
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• pp.295-304
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• 2009

To understand the properties of soil in Dokdo, we collected soil samples from 12 locations on Seodo and 23 locations on Dongdo, in Dokdo of Gyeongsangbuk-do Province in 2007-2008 and analyzed the soil's physical and chemical characteristics. Sand comprises the largest component (49.37%) of Dokdo soil, followed by silt (40.70%) and clay (9.93%). The soil structure consists mostly of sand loam, followed by loam and silt loam. The pH level of soils from Dokdo varied dramatically among sampling sites and seasons, ranging from 3.36 to 8.02. The total ion content of Dokdo soil also varies greatly among survey places and periods, but in general the total ion content was high in summer when vegetation develops, and low in spring. The exchangeable cation contents of the soil showed low levels in samples where the soil pH was low, including habitats dominated by Agropyron tsukushiense var. transiens and Echinochloa crus-galli, whereas the exchangeable cation contents were high where the organic contents were high, as in habitats dominated by Liriope platyphylla and Artemisia japonica subsp. littoricola. Soil N contents varied greatly among survey sites and higher N contents were found in soil inhabited by Chenopodiaceous plants than in habitats inhabited by other plants. The substantial differences in phosphorus contents among sites were related to excrement of black-tailed gulls. To understand the basic physical and chemical features of the soil on Dokdo, it will be necessary to conduct seasonal and long-term research on soil pH, ion contents, organic contents, N and P, as well as obtaining precise data from samples collected at different depths.

• Journal of Korea Soil Environment Society
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• v.4 no.2
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• pp.55-62
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• 1999

The solvent flushing apparatus for soil remediation was designed. After the soil around nuclear facilities was sampled and compulsorily contaminated by Co, the characteristics remediated by solvent flushing were analyzed. Meanwhile, the nonequilibrium sorption code was developed for modelling of the soil remediation by solvent flushing, input parameters needed for modelling were measured by laboratory experiment. Experimental results are as follows : The soil around nuclear facilities belongs to Silt Loam including a lot of silt and sand. When water was used as a solvent, the higher was the hydraulic conductivity. the higher the efficiency of soil remediation was. The values calculated by the nonequilibrium sorption code agreed with experimental values more exactly than the values calculated by the equilibrium sorption code. When EDTA solution was used as a solvent. the soil remediation efficiency by EDTA solution showed higher than that by water.