• Korean Journal of Soil Science and Fertilizer
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• v.43 no.1
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• pp.1-7
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• 2010

This study was carried out to investigate plow pan characteristics and to grasp the relationship between its particle size distribution fractal dimension ($D_m$) and water transport in paddy plow pan. Twenty four soil sampling sites with different management groups, ordinary and sandy-textured, were selected and investigated for physical properties of soils such as Yamanaka hardness in April, non-submerged condition, before rice seedling transplanting. The plow pan appearing depth and thickness was determined by penetration resistance profile. Undisturbed core samples with five replicates were sampled at plow pan layerwith 2 inch cores for measuring soil bulk density and saturated hydraulic conductivity. The particle size distribution fractal dimension ($D_m$) was calculated by the method following the procedure Tylerand Wheacraft (1992), using the USDA-based particle size analysis datawith fractions of 0-0.002, 0.002-0.053, 0.053-0.1, 0.1-0.25, 0.25-0.5, 0.5-1.0, and 1.0-2.0 mm. The plow pan of investigated fields appeared at a range from 5 to 30 cm depth, showing minimum value in sandy-textured management group and maximum value in ordinary management group. The thickness of plow pan were distributed from 5 to 17 cm, showing both minimum and maximum values in sandy-textured management group. Averagely, the plow appearing depth were deeper in ordinary management group than in sandy-textured management group, whereas the reverse in the thickness of plow pan. The particle size distribution fractal dimension ($D_m$) had higher value with finer textures, with higher fractality in coarser texture. Saturated hydraulic conductivities, $K_s$, of plow pan soils distributed from 0.5 to 1420 mm $day^{-1}$, having the highest value in sandy skeletal soils. The $K_s$ decreased with decreasing clay content and $D_m$, showing power function relationships. The coefficient of determination, $R^2$, of the fitted power functions were higher in $D_m$ as x-axis than in clay content. This means that $D_m$ could give us more effective estimation than clay content. Especially, sandy-textured paddy soils had higher $R^2$, compared to ordinary paddy soils. $K_s$ of relatively coarse-textured soils with less than 18%of clay content, therefore, was more dependent on particle size distribution than that of relatively fine-textured soils. From these results, it could be concluded that the fractal scaling gives us a unique quantity describing particle size distribution and then can be applied to estimate saturated hydraulic conductivity, especially more effective in coarse-textured soils.

• The Korean Journal of Pesticide Science
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• v.10 no.4
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• pp.296-305
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• 2006

The adsorption and persistence of pencycuron {1-(4-chlorobenzyl) cyclopentyl-3-phenylurea} in soils were investigated under laboratory and field conditions to in order to assess the safety use and environmental impact. In the adsorption rate experiments, a significant power function of relation was found between the adsorbed amount of pencycuron and the shaking time. Within one hour following the shaking, the adsorption amounts in the SCL and the SiCL were 60 and 65% of the maximum adsorption amounts, respectively. The adsorption reached a quasi-equilibrium 12 hours after shaking. The adsorption isotherms followed the Freundlich equation. The coefficient (1/n) indicating adsorption strength and degree of nonlinearity was 1.45 for SCL and 1.68 to SiCL. The adsorption coefficients ($K_d$) were 2.31 for SCL and 2.92 to SiCL, and the organic carbon partition coefficient, $K_{oc}$, was 292.9 in SCL and 200.5 inSiCL. In the laboratory study, the degradation rate of pencycuron in soils followed a first-order kinetic model. The degradation rate was greatly affected by soil temperature. As soil incubation temperature was increased from 12 to $28^{\circ}C$, the residual half life was decreased from 95 to 20 days. Arrhenius activation energy was 57.8 kJ $mol^{-1}$. Furthermore, the soil moisture content affected the degradation rate. The half life in soil with 30 to 70% of field moisture capacity was ranged from 21 to 38 days. The moisture dependence coefficient, B value in the empirical equation was 0.65. In field experiments, the half-life were 26 and 23 days, respectively. The duration for period of 90% degradation was 57 days. The difference between SCL and SiCL soils varied to pencycuron degradation rates were very limited, particularly under the field conditions, even though the characteristics of both soils are varied.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.137-137
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• 2017

우리나라는 산지가 64%를 차지하고 있기 때문에 토양침식 위험성이 큰 급경사지가 많다. 산지사면 토양은 대부분 사질토와 사양토로 이루어졌다. 급경사면에서의 토양침식이 많이 발생함에도 이에 대한 연구결과는 부족한 실정이다. 본 연구에서는 사양토로 구성된 나지사면에 대한 토양침식 특성을 파악하고자 강우모의 실험을 수행하였다. 강우모의 실험의 강우강도는 전국의 확률강우분포 3~200년 빈도의 30분 강우강도인 60mm/hr~130mm/hr의 범위였다. 사면경사는 급경사지 범위을 대표하는 $24^{\circ}$와 $28^{\circ}$에서 실험을 하였다. 실험은 발생하는 지표유출과 지표하유출를 수집하여 측정하였으며, 지표표면에 잉크를 뿌린 다음 실험을 동영상 촬영하여 속도를 측정하였다. 지표유출량을 건조로에 넣고 건조시켜 토양침식량을 측정하였다. 그리고 강우운동에너지는 광학디스트로메터(Pasivel)을 이용하여 측정하였다. 강우운동에너지를 측정한 결과 $800J/m^2{\sim}1700J/m^2$ 범위였다. 강우강도가 클수록 지표유출량과 토사유출량은 증가하였다. 경사가 증가함에 따라 지표유출량은 큰 변화가 없으나, 토양침식량은 크게 증가하였다. 지표하유출량은 강우강도와 경사가 증가하여도 큰 변화가 없었으며, 강우 발생이 멈추면 즉시 감소하였다. 사양토의 점토성분이 강우의 침투를 저해하고, 모래보다 많은 양의 물을 함유하는 있는 것으로 파악 되었다. 그러나 사질토보다 토양입자가 작은 사양토에서 상대적으로 많은 토양침식이 발생하였다. 강우에너지가 증가하면 유사농도는 감소하는 경향을 보였다. 이는 강우에너지가 증가함에 따라 지표유출량의 증가율에 비해 토양침식량의 증가율이 작기 때문인 것으로 판단된다.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.2
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• pp.95-100
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• 1999

Hydrocarbon compounds in vadose zone soils caused by adsorption onto the surfaces of solid particles are generally considered to show retardation effect. In this study, we investigated the retardation effect on the transport of Benzene in a sandy soil by conducting batch and column tests. The batch test was conducted by equilibrating dry soil mass with Benzene solutions of various initial concentrations. and by analyzing the concentrations of Benzene in initial and equilibrated solutions using HPLC. The column test consisted of monitoring the concentrations of effluent versus time known as a breakthrough curve (BTC). We used KCl and Benzene solutions with the concentration of 10 g/L and 0.88 g/L as a tracer, and injected them into the inlet boundary of the soil sample as a square pulse type respectively, and monitored the effluent concentrations at the exit boundary under a steady state condition using an EC-meter and HPLC. From the batch test, we obtained a distribution coefficient assuming that a linear adsorption isotherm exists and calculated the retardation factor based on the bulk density and porosity of the column sample. We also predicted the column BTC curve using the retardation factor obtained from the distribution coefficient and compared with the measured BTC of Benzene. The results of the column test showed that i) the peak concentration of Benzene was much smaller than that of KCl and ⅱ) the travel times of peak concentrations for the two tracers were more or less identical. These results indicate that adsorption of Benzene onto the sand panicles occurred during the pulse propagation but the retardation of Benzene caused by adsorption was not present in the studied soil. Comparison of the predicted with the measured BTC of Benzene resulted in a poor agreement due to the absence of the retardation phenomenon. The only way to describe the absolute decrease of Benzene concentration in the column leaching experiment was to introduce a decay or sink coefficient in the convection-dispersion equation (CDE) model to account for an irreversible sorption of Benzene in the aqueous phase.

• Economic and Environmental Geology
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• v.34 no.4
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• pp.417-422
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• 2001

Sutfactants may be used in remediation of subsoil and aquifer contaminated with hydrophobic compounds. The objectives of this study were to select potentially suitable sUlfactants that solubilize toluene present as a contaminant and to determine the effectiveness of toluene removal from Ottawa sand by the selected surfactants. Material used as the model soil was Ottawa sand and the organic used as model contaminant was toluene. Used experimental methods were separatory funnel experiment and shaker table agitation/centrifugation experiments. Based on the experimental results, the following conclusions were drawn; t) In the surfactant selection, six different surfactants were chosen based on surfactant types, toxicity, and water solubility. These six were focused into two on the basis of HLB and surface tension study, separatory funnel experiment, shaker table and centrifugation experiments. The two most suitable surfactants were Sandopan JA36 (an anionic surfactant), and Pluronic L44 (a non-ionic surfactant). 2) In the shaker table agitation and centrifugation experiments, the highest recovery of the toluene was 96% which was obtained with one surfactant wash plus two water rinses using an anionic surfactant (Sandopan JA36).

• Korean Journal of Soil Science and Fertilizer
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• v.14 no.2
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• pp.95-103
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• 1981

This study was conducted to evaluate the effects of application of several soil amendment materials to an alluvial sandy soil on the rice growth and yield during the 1979. The materials used were the combinations of rice straw, rice hull, silicate fertilizer, red earth and zeolite. The results obtained were summarized as follows : 1. The application of soil amendment materials considerably increased the number of tillers, plant height and dry matter of rice plant. Particularly, the zeolite treated plot resulted in much better growth in the late stage rather than in the early stage. 2. The plots treated with silicate fertilizer, rice hull and zeolite significantly increased the rice yield and so did those with red earth statistically at 5 % level. However, it was not significant with rice straw. 3. By the application of these materials, the silica content in rice plant was continuously increased untill the heading stage, the nitrogen content was high at the maximum tillering stage and the panicle initiating stage and the phosphorus content was high at panicle initiating stage, which were censidered to be the factors of yield increase. However, in the straw treated plot, the contents of nitrogen, phosphorous and potassium were high, while the silica content was low in rice plant. 4. Further, soil pH, C. E. C., content s of organic matter and silicate in soil treated with those materials were increased after experiment. compared with in the soil before experiment.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.1
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• pp.7-13
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• 1983

Laboratory determinations of saturated hydraulic conductivity were conducted with four soils varying in texture from sand to clay and with five waters with different salinity level. The waters varied in total dissolved solids from 1,250 to $15,000mg/{\ell}$ and in SAR from 16 to 57 and were representative of saline waters in New Mexico. Saturated hydraulic conductivities of the soils were not significantly affected by water salinity if these waters were the sole source of irrigation water. However, small additions of distilled water, assuming simulated to rain, to soils previously equilibrated with the saline waters significantly decreased soil permeability. Dispersion and short or long-distance transport of clay apparently clogged conducting pores when distilled water was introduced. Swelling was an important mechanism in reducing soil permeability only in the clay soil. The data suggest that, when saline water is the dominant irrigation source and is supplemented by rain, (1) all saline waters could be used on very sandy soils, (2) no saline waters should be used on very heavy soils, and (3) slightly saline, but not very saline, waters could be used on medium-textured soils.

• Korean Journal of Soil Science and Fertilizer
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• v.15 no.2
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• pp.101-109
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• 1982

An attempt to determine the optimum levels of P and K fertilizers application for Tong-il lines (indica${\times}$Japonica) was made with the data obtained from the farm fields during 1976 to 1979. The detailed interpretation to obtains relationships between fertilizer recommendation of P and K with their balance with Ca and Mg contents in soil were made using yield data obtained in 1977. The results were summarized as follows : 1. The optimum rates of P and K fertilizer application varied with the kinds of paddy soils showing the ranges of 6.6-11.4 kg/10a for P (as $P_2O_5$) and 7.0-11.3 kg/10a for K (as $K_2O$). The amounts of optimum fertilizers increased in the order of unmatured soil, normal soil, sandy soil, saline soil, poorly drained soil for P, and unmatured soil, poorly drained soil, sandy soil, normal soil, saline soil for K. 2. The yield increment at the optimum levels of P and K in comparison with no fertilizer application were 3,5-7.5% for P and 2.1-9.1% for K. The effectiveness of P was greatest in the unmatured soils and that of K was greatest in the poorly drained soils, and in the saline soil, that of P and K was relatively high. 3. According to relationship between relative yield index and soil testing value, the critical $P_2O_5$ contents which showed the yield response in soil were about 100 ppm for normal soil and 200ppm for sandy soil. That of exchangeable K/Ka+Mg ratio in soil were about 0.08 for normal paddy soil and over 0.08 for sandy soil, and those for poorly drained soils were not obtained in the ranged below 0.08. 4. The regression equations of fertilizer recommendation for different soils were obtained between the available $P_2O_5$ in soil or ratio of K to base including Ca and Mg in soil (x) and the amount (Y) of P and K fertilizers applied. The equations for phosphorus recommendation were Y=11.27C-0.048x for normal paddy soil and Y=13.383-0.061x for sandy soil, and those for potassium recommendation were Y=9.526-0.569x for normal paddy soil, Y=11.727-1.004x for sandy soil, and Y=12.574-0.558x for poorly drained soil, respectively.

• The Korean Journal of Mycology
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• v.10 no.3
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• pp.119-124
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• 1982

The characteristics of the six different agricultural soil from Michigan were as follows. Colwood and Capac soil were loam, Gilford and Ceresco were sandy clay loam, Sission was clay loam, and Spinks was sandy loam. pH of Gilford sandy clay loam was 6.6 whereas that of the soil ranged $5.4{\sim}5.9$. Gilford sandy loam found to contain a relatively higher amount of organic matters as compared to other soils. Furthermore, the numbers of bacteria in Gilford sandy clay loam were significantly higher than those in other soils. The populations of fungi in Gilford sandy clay loam and Colwood loam soils were significantly greater than those in other soils. On the other hand, the densities of actinomycetes in Gilford sandy clay loam and Ceresco sandy clay loam soils were significantly different from those in other soils. The population of anaerobic bacteria varied depending on the soils; Ceresco sandy clay loam, Capac loam, Colwood loam soils have higher numbers of bacteria, whereas Gilford sandy clay loam was very lesser than the other soils. In the $^{14}C-glucose$ respiration by soil microorganisms after 10 hrs, the respiration rate was decreasing in the order of Ceresco sandy clay loam, Spinks sandy loam, Colwood loam, Sission clay loam, Capac loam and Gilford sandy clay loam. Germination of test propagules on natural soil soil was $0{\sim}5%$, and it was germinated $90{\sim}98%$ on autoclaved soil and PDA. The propagules differed in thier germination response to nutrients added to the soils. In general, more nutrients were required to promote germination on Capac loam and Gilford sandy loam soil than Spinks sandy loam soil. Especially Mortierella n. sp. required more nutrients for germination to obtain the same ratio as Helminthosporium victoriae.

• The Journal of the Petrological Society of Korea
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• v.9 no.1
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• pp.13-28
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• 2000

Chojeong area is mainly composed of the Ogcheon Group which consists of regionally metamorphosed, age-unknown sedimentary rocks. In the northwestern parts, the Group is intruded by the Jurassic Daebo granite and Cretaceous felsic and mafic dykes. The lowermost, Midongsan Formation which consists of milky white impure quartzite, crops out along the anticline axes with N40E trend. Ungyori quartzite Formation is intercalated with quartzite and slate. Miwon Formation is most widely exposed in the area and consists mainly of phyllitic sandy rocks with a thin crystalline limestone bed. Hwajeonri Formation is divided into two parts, pelitic lower and calcareous upper parts, composed with phyllite and slate. Changri and Hwanggangri Formations are typical members of Ogcheon Group, the former bearing coally graphite seams consists mainly of black slate and phyllite with intercalated greenish grey phyllite, the latter is pebble bearing phyllite formation of which matrix and pebbles are variable in compositions and size. Biotite granite, porphyritic granite and two mica granite belong to Jurassic so-called Dabo granite. They intruded the Ogcheon Group forming vast contact metarnophic zone. Quartz porphyry, mafic dyke and felsite intruded along the marginal zone of porphyritic granite batholith and fracture of NS trend. Main structural lineaments in Ogcheon Group shows N25-45E, NS and N30-45W trends. The N25-45E trends are mainly from general ductile deformation during regional metamorphism, showing isoclinal folding, Fl foliations and lithological erosional characters. Some of these trends are due to normal faults. The NS and N30-45W trends represent brittle deformation including faults and joints. In the area of granitic batholith, NS to N30- 45 trends are from the direction of dykes. In the soils of the area, average contents of heavy metal elements such as Cd, Cr, Cu, Pb, and Zn are 0.2, 50.6, 35.5, 27.9, and 93.4 ppm respectively, which are not higher than the average values of natural soils, under the tolerable level. Enrichment Index does not show any heavy metal pollution in the area. Average depths of weathering(5m vs. 2m), porosities(43.94 vs. 51.80), densities(l.29 vs. 1.15), and permeabilities(2.52 vs. 8.07) are comparable in granite areas and in the phyllite areas of Ogcheon Group.