• Korean Journal of Soil Science and Fertilizer
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• v.36 no.1
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• pp.1-7
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• 2003

Time domain reflectometry (TDR) is a newly developed method for measuring simultaneously solute concentrations and volumetric water content of soil. Bulk electrical conductivity ($EC_a$) of soil is obtained from TDR signal using several equations proposed, and electrical conductivity of soil solution ($EC_w$) can be calculated using the linear relationship $EC_a=EC_w\theta(a\theta+b)+EC_s$ between $EC_a$ and $EC_w$ at constant soil water content. The objectives of this study were to evaluate $EC_a$ proposed by several workers and to obtain the empirical constants (a, b, and $EC_s$) for $EC_w$ of the soils from A, Bl, and B2 horizon of an agricultural field (Coarse loamy, Fluvaquentic Eutrudepts). The $EC_a$ proposed by Yanuka et al. responded most sensitively to the KCl solute concentrations. The empirical constants of a, b, and $EC_s$ for $EC_w$ were -0.249, 1.358, and 0.054 for A horizon, -2.518, 2.708, and 0.097 for Bl horizon, and 2.490, -0.250, and 0.103 for B2 horizon, respectively. Therefore, the results of this study showed that Yanuka et al. equation was most useful one in determining $EC_a$, from TDR signal for agricultural soil with low salinity and that the empirical constants for the calculation of $EC_w$, from $EC_a$ can be obtained through a simple calibration experiment.

• Journal of Korean Society of Forest Science
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• v.79 no.4
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• pp.376-387
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• 1990

A research effort has been made to determine soil buffer capacity in forest soils nearby urban and industrialized regions. Buffer capacities of soils from four regions were measured by different pH levels of artificial acid precipitation. The following conclusions have been drawn in response to the overall research objectives. Soil Suffer capacity was the highest in Kangwondo followed by Uisan, Yeochon and Seoul when simulated acid precipitation were treated at the level of pH 3.0-5.7. With the acid precipitation treatment below pH 2.0 level, however, the capacity dropped seriously with no significant differences between the regions. In Kangwondo region soils weathered from granite and limestone showed significant differences in the buffer capacities. Soil collected in Seoul and Ulsean revealed that the capacities tended to increase with the distance from the pollution sources when treated at pH 3.0, 4.5 and 5.7 level of acid precipitation. The major mechanism of soil buffer observed during simulated acid precipitation experiment was canon exchange for Kangwondo forest soils. In Seoul region canon exchange also played an important role in soil buffering under artificial acid precipitation between 3.0 and 5.7 pH levels, yet under pH 2.0 level aluminum and silicate hydrolysis. In Ulsan canon exchange was a msjor determinant for the buffer capacity above pH 4.5 level, between pH 3.0-4.5 aluminum hydrolysis and below pH 3.0 aluminum and silicate hydrolysis. In Yeochon silicate hydrolysis led buffer capacity above pH 4.5 and below pH 4.5 aluminum hydrolysis.

• Economic and Environmental Geology
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• v.45 no.2
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• pp.137-144
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• 2012

Soil pan typically presents the problems in soil water movement or in aeration which is not appropriate for a plant root growth, In this study physico-chemical characteristics of soils and micromorphological characteristic of clay accumulated zone were investigated to identify redox characteristic and evolution of a fragipan of Gangreung series commonly developed in coastal terraces. Gangreung series is classified as Aquic Fragiudalfs according to the USDA soil taxonomy. It is known that sedimentary ocean floor results in soil pan having parallel liner soil structure due to landscape evolution around 200 to 250 million years ago. it is considered that illite, kaolinite, and vermiculite are major clay minerals contained in a fragipan of Gangreung series. Mixed gray and reddish brown colored band around soil pores was found and would be the redoxmorphic features of fragipan. It is possibly due to accumulated illuvial clay and ferriargillans in soil pores and aggregates in reducing conditions eluding ferrous material. Therefore, mixed colored band around pores in soils of Gangreung series would be developed from the eluted ferrous materials which were accumulated in fragipan during the emerged land formation.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.2
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• pp.127-132
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• 1992

This experiment was conducted to find out the useful data for upland crop cultivation in the newly reclaimed tidal land. Poseung silty clay loam soil was selected, and cotton(Mogpo VII) and tall fescue were cultivated under different drainage systems and soil ameliorator applications. Soil hardness and bulk density were decreased by subsurface drainage and plastic film installed at 40cm depth of the soil. Red earth application was also effective to loosen the soil, but zeolite and gypsum made the subsoil compact. Water content of the soil was high in surface drain than that of subsurface drain or plastic film curtain plot during dry season. The water content was in order of plastic film curtain, surface drain and subsurface drain. Electrical conductivity(EC) was decreased to lower than 0.4 Simens $meter^{-1}$ ($SM^{-1}$) in the subsurface drain during rainy season, and the EC of subsurface drain was maintained a quater to an half of surface drain. The yield of cotton and tall fescue were high in order of subsurface drain, plastic film curtain and surface drain plot. The yields of cotton were increased to 36-73 % by ameliorator application, and the red earth application was more effective for tall fescue growth compare to gypsum and zeolite.

• The Korean Journal of Ecology
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• v.28 no.6
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• pp.389-393
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• 2005

This study was carried out to investigate the effects of soil acidification on the growth of 3-year-old Pinus densiflora seedlings grown for 21 weeks in brown forest soils acidified with $H_2SO_4$ solution. The concentrations of Al in the acidified soils were increased with increasing amount of $H^+$ added to the soil. The total dry weight of the seedlings was reduced by the addition of the $H_2SO_4$ solution. In addition, there was a strong positive correlation (r=0.97, p<0.01) between the dry weight of the seedlings and the molar (Ca+Mg+K)/Al ratio of the soil. The seedlings with the molar (Ca+Mg+K)/Al ratio of 1.0 resulted from approximately 50% growth reduction compared with the control value. The results suggest that the molar (Ca+Mg+K)/Al ratio of the soil may be a useful indicator for assessing the critical load of acid deposition.

• Korean Journal of Environmental Agriculture
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• v.16 no.4
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• pp.304-310
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• 1997

In greenhouse, a mixed solution of Mn-54, Co-60, Sr-85 and Cs-137 was applied to the soil of culture boxes 2 days before sowing cucumber and at 4 different times during its growth for measuring their transfer factors (TFs) for fruit and migration in soil. TFs varied with radionuclide, application time and harvest time by factor of up to about 60. Variations in TFs with application time showed different patterns among radionuclides. TFs decreased on the whole in the order of Sr-85 > Mn-54 > Co-60 > Cs-137. TFs of Mn-54, Co-60 and Cs-137 mixed with topsoil before sowing were a little higher than those for the soil-surface application made at an early growth stage while no difference in Sr-85 TF was found. After harvest, soil concentrations of the radionuclides applied at an early growth stage were examined. They decreased with increasing soil depth and 80${\sim}$99% of the radioactivity remained in the top 3cm. Soil pemeation of the radionuclides migration decreased in the order of Sr-85 > Mn-54 > Co-60 > Cs-137. The present data can be utilized in estimating radionuclide concentration in cucumber fruit, taking proper measures for its harvest and consumption and designing the best way of soil decontamination following an radioactive deposition during the cucummber growing season.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.5
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• pp.369-375
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• 2000

To find a quick test procedure for soil nitrate concentration, two methods, i.e. "Nitracheck 404" reflectometer (Eijkelkamp, Netherlands) with nitrate test strip and a portable colorimeter "Hanna Ion Specific meter(USA) with a color development reagent, were tested for twenty soils with different nitrate contents ranged between from $10mg\;kg^{-1}$ to $340mg\;kg^{-1}$. The standard deviation, coefficient of variability, and recovery from these quick test procedures were compared with those measured by conventional Kjeldahl distillation method and nitrate ion electrode method. The nitrate concentration measured by portable colorimeter method was higher in soils with low concentration and lower in soils with high concentration than those measured by conventional methods. However, concentrations measured by test strip reflectometer method was showed the similar coefficient of variability and recovery as those by conventional methods for all soil samples. From the experimental results in this study, the test strip reflectometer method was thought to be recommendable one revealed the satisfied results for accuracy, quickness, and simplicity for field test of soil nitrate concentration.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.5
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• pp.238-246
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• 2005

We conducted this investigation to observe competitive adsorption phenomena among the heavy metals onto the available sorption sites of soil particle surfaces in sandy clay loam and clay soil collected from Nonsan city, Chungnam and Yoosung, Daejeon in Korea, respectively. Polluted and contaminated soils can often contain more than one heavy metal species, resulting in competition for available sorption sites among heavy metals in soils due to complex competitive ion exchange and specific sorption mechanism. And the adsorption characteristics of the heavy metals were reported that the selectivity for the sorption sites was closely related with electropotential and electro negativity carried by the heavy metals. The heavy metals were treated as single, binary and ternary systems as bulk solution phase. Adsorption in multi-element system was different from single-element system as Cr, Pb and Cd. The adsorption isotherms showed the adsorption was increased with increasing equilibrium concentrations. For binary and ternary systems, the amount of adsorption at the same equilibrium concentration was influenced by the concentration of individual ionic species and valence carried by the respective heavy metal. Also we found that the adsorption isotherms of Cd and Pb selected in this experiment were closely related with electronegativity and ionic potential regardless number of heavy metals in solution, while the adsorption of Cr carried higher valance and lower electro negativity than Cd and Pb was higher than those of Cd and Pb, indicating that adsorption of Cr was influenced by ionic potential than by electronegativity. Therefore adsorption in multi-element system could be influenced by electronegativity and ionic potential and valance for the same valance metals and different valance, respectively. But it still needs further investigation with respect to ionic strength and activity in multi-element system to verify sorption characteristics and reaction processes of Cr, especially for ternary system in soils.

• Economic and Environmental Geology
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• v.52 no.1
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• pp.1-12
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• 2019

Batch experiments for the soil washing coupled with the magnetic separation process were performed to remediate the soil contaminated with metal and oil wastes. The soil was seriously contaminated by Zn and TPH (total petroleum hydrocarbon), of which concentrations were 1743.3 mg/kg and 3558.9 mg/kg, respectively, and initial concentrations of Zn, Pb, Cu, and TPH were higher than the 2nd SPWL (soil pollution warning limit: remediation goal). The soil washing with acidic solution was performed to remove heavy metals from the soil, but Pb and Zn concentration of the soil maintained higher than the 2nd SWPL even after the soil washing with acidic solution. The 2nd soil washing was repeated to increase the Pb and Zn removal efficiency and the Zn and Pb removal efficiencies additionally increased by only 8 % and 5 %, respectively, by the 2nd soil washing (> 2nd SPWL). The small particle separation from the soil was conducted to decrease the initial concentration of heavy metals and to increase the washing effectiveness before the soil washing and 4.1 % of the soil were separated as small particles (< 0.075 mm in diameter). The small particle separation lowered down Zn and Pb concentrations of soil to 1256.3 mg/kg (27.9 % decrease) and 325.8 mg/kg (56.3 % decrease). However, the Zn concentration of soil without small particles still was higher than the 2nd SPWL even after the soil washing, suggesting that the additional process is necessary to lower Zn concentration to below the 2nd SPWL after the treatment process. As an alternative process, the magnetic separation process was performed for the soil and 16.4 % of soil mass were removed, because the soil contamination was originated from unreasonable dumping of metal wastes. The Zn and Pb concentrations of soil were lowered down to 637.2 mg/kg (63.4 % decrease) and 139.6 mg/kg (81.5 % decrease) by the magnetic separation, which were much higher than the removal efficiency of the soil washing and the particle separation. The 1st soil washing after the magnetic separation lowered concentration of both TPH and heavy metals to below 2nd SPWL, suggesting that the soil washing conjugated with the magnetic separation can be applied for the heavy metal and TPH contaminated soil including high content of metal wastes.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.5
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• pp.322-328
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• 2004

Available nutrients in soil solution play key roles on the growth of plants, but the equilibria in soil solution can be disturbed by acid precipitation. In this study, we investigated the relationships between element concentrations in the needles of Pinus thunbergii and chemical properties of forest soil solutions in the industrial complexes as an effort to find the possible limiting factor(s) causing the forest decline. The Ca/Al molar ratios in needles of Pinus thunbergii collected from the control sites were 18. However, at Onsan and Ulsan industrial complexes, those were decreased to the ranges from 10 to 11 for the one-year old needles and from 9 to 10 for the two-year old needles. The Mg/Al molar ratios showed similar tendencies with the Ca/Al molar ratios of the needles of Pinus thunbergii. In the A horizon, there existed a significant correlation between Mg concentrations in the needles of Pinus thunbergii and Ca/Al molar ratio of forest soil solution. Calcium concentrations in the needles of Pinus thunbergii in the B horizon were also significantly correlated with Ca/Al molar ratios of forest soil solutions. The uptakes of Ca and Mg by Pinus thunbergii were mainly limited by Al in the soil solutions of the A horizon and by Mn and Al in the soil solutions of the B horizon.