• Applied Biological Chemistry
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• v.26 no.2
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• pp.97-103
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• 1983

To get further information on the behavior of phorate(0,0-diethyl S-ethylthiomethyl phosphorodithioate) in soil under the subtropical conditions, a field experiment has been conducted. Phorate granule (10%) was applied to silt loam soil at the rate of 40kg a.i./ha and incorporated to 10cm soil depth. Residues of phorate and its metabolites in soil were determined with GLC and confirmed qualitatively with TLC. Phorate was rapidly oxidized to its sulfoxide and sulfone. Therefore, main metabolic pathway of phorate in soil was the oxidation of phorate to phorate sulfoxide and sulfone. Phorate sulfoxide and sulfone were relatively more persistent than phorate itself. Phoratoxon was detected at low level only up to 30 days after treatment and its sulfoxide and sulfone were not detected during the whole experimental period. Toluene-acetonitrile-nitromethane(40 : 30 : 30, v/v/v) solvent system separated satisfactorily phorate and its five metabolites. Most of the residues was found in the initial incorporation depth $(0{\sim}10cm)$. Consequently, insecticides showed a little downward movement.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.4
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• pp.207-215
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• 2002

Changes in salinity, hydraulic conductivity and penetration resistance in a reclaimed tidal land reclaimed in 1986 were studied. The salinity monitoring based on electrical conductivity of saturated extract, ECe, was conducted from 1994, when the land use for experimental crop production started after tile drainage. The site was abandoned since 1999. The hydraulic conductivity was measured by a sand fill auger hole method, and the resistance was measured with a dynamic penetrometer in situ. The averaged ECe in 1994 was $33.7dS\;m^{-1}$ ranging from 25.5 to $44.8dS\;m^{-1}$, and was decreased to $25.7dS\;m^{-1}$ with large range from 0.8 to $70.3dS\;m^{-1}$ before experiment was $1.89{\times}10^{-7}m\;s^{-1}$. It increased to $1.32{\times}10^6m\;s^{-1}$ in the top 20-cm soil with large variability, while it showed $3.44{\times}10^7m\;s^{-1}$ beneath the 20-cm soil depth with less variability. The penetration resistance of the soil ranged from 0.05 to 9.99MPa. The vertical distribution of penetration resistance indicated the hardened layer was developed at the depth of 20~40 cm where the hydraulic conductivity was sharply decreased.

• Journal of Korean Society of Forest Science
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• v.113 no.1
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• pp.14-30
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• 2024

This study characterized areas at risk of land creep by focusing on a site that has undergone this phenomenon in Ulju-gun, South Korea. Land creep in the area of interest was catalyzed by road expansion work conducted in 2022. The site was examined on the basis of its geological features, topography, effective soil depth, soil hardness, electrical resistivity, and subsurface profile. It consists of a slope covered with sparse vegetation and a concave top that retains rainwater during rainfall. Compositionally, land creep affected the shale, sandstone, and conglomerate formations on the site, which had little silt and more sand and clay compared with areas that were unaffected by land creep. An electrical resistivity survey enabled us to detect a groundwater zone at the site, which explains the softness of the soil. Finally, the effective soil depth at the land creep-affected area was 30.4 cm on average, indicating deep colluvial deposits. In contrast, unaffected sites had an effective soil depth of 24.7 cm on average. These results should facilitate the creation of systems for monitoring and preemptively responding to land creep, significantly mitigating the socioeconomic losses associated with this phenomenon.

• Korean Journal of Environmental Agriculture
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• v.29 no.1
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• pp.20-26
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• 2010

This study was conducted to reclassify Donggui series based on the second edition of Soil Taxonomy and to discuss the formation of Donggui series in Jeju Island. Morphological properties of typifying pedon of Donggui series were investigated and physico-chemical properties were analyzed according to Soil survey laboratory methods manual. The typifying pedon has very dark grayish brown (10YR 3/2) silt loam A horizon (0~17 cm), gravelly very dark grayish brown (10YR 3/2) silt loam BA horizon (17~42 cm), gravelly very dark grayish brown (10YR 3/2) silty clay loam Bt1 horizon (43~80 cm), brown (7.5YR 4/6) silty clay Bt2 horizon (80~105 cm), and brown (10YR 5/4) silty clay Bt3 horizon (105~150 cm). It is developed in lava plain and are derived from basalt and pyroclastic materials. The typifying pedon contains 1.3~2.1% oxalate extractable (Al + 1/2 Fe), less than 85% phosphate retention, and higher bulk density than 0.90 $Mg/m^3$. That can not be classified as Andisol. But it has an argillic horizon from a depth of 22 to 150 cm and a base saturation (sum of cations) of less than 35% at 125 cm below the upper boundary of the argillic horizon. That can be classified as Ultisol, not as Andisol and Inceptisol. It has udic soil moisture regime, and can be classified as Udalf. Also that meets the requirements of Typic Hapludalf. It has 18-35% clay at the particle-size control section, and have thermic soil temperature regime. Therefore Donggui series can be classified as fine loamy, mixed, thermic family of Typic Hapludalfs, not as fine silty, mixed, thermic family of Dystric Eutrudepts.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.4
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• pp.307-314
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• 1989

Barley, garlic, and soybean were cultivated in the silt loam, sandy loam, and loam, respectively, and the absorbing patterns of N, P, and K during growing of the crops were determined. While, the leaching of N, P, and K applied in the above soils in four levels of topsoil depths and in four leachate levels of excess precipitation was measured through the column. The depths of the soil were devised to 20, 35, 50, and 65cm, and the levels of excess water were classified to each leachate of 20, 40, 60, and 80mm precipitation, and nitrogen, phosphorous, and potassium in each fraction of the leachate were analyzed. By the analyses of the chemical components during growth of the crops, their absorbing patterns of N, P, and K were investigated. The order of N-leachings in the soils was sandy loam > loam > silt loam, and the leaching of $K_2O$ was very similar to N. The leaching of $P_2O_5$ was slight in all kinds of the soils. By the combination of the absorbing patterns of the crops in three kinds of soils and the leaching of the nitrogen in four levels of soil depth and four levels of excess precipitation, the method to replace the nitrogen lost by leaching was presented.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.4
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• pp.241-248
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• 1993

An experiment was conducted in 1990~1991 to study the effects of various soil amelioration on the soil productivity and machine workability at tidal land paddy field of Kyewhado Substation, Homam Crop Experiment Station. The soil, Munpo Series(fine sandy loam, Typic Fluvaquents) was treated with gipsum, rice straw, rice straw compost and foreign soil(at 20cm depth) after deep ploughing. The results are surmerized as follows. 1. Sand and clay were slightly increased, while silt was slightly decreased in the rice straw and compost plots. The soil texture was changed from loam to sand loam by the addition of foreign soil 2. Soil bulk density and porosity was decreased in the rice straw, compost and foreign soil addition plots. 3. Cone penetration resistance was $12.5kg/cm^2$ at 10cm of soil depth before experiment and $12.5kg/cm^2$ at 20cm of soil depth after experiment except control, and the root zone was expended down to 20cm. 4. Soil salt content before experiment was 0.46 and 0.48% for surface soil(10cm) and subsoil(20cm), respectively ; The salt content of ameliorated plot was 0.26~0.32% and 0.16~0.31%, respectively, indicating good leaching of soil salt by the soil improvements. 5. The yields of rice in different treatments were in the order of the foreign soil addition > compost > gypsum > rice straw > control.

• Journal of The Korean Society of Grassland and Forage Science
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• v.13 no.4
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• pp.238-250
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• 1993

Sixty two natural habitats of Korean lespedeza (Lespedeza stipulacea Maxim) were investigated to obtain basic data on the plant growth and the soil physico-chemical properties such as pH, mineral elements, organic matter content, soil separats and texture. Analyzed results can be summarized as follows. 1. Plant height and dry matter yield of the samples higher in late August and early September, although they varied greatly depending on the sampling date and location. 2. The plant shoot should higher contents of N, P, K. Ca and Mn than root and the plant root was higher in Mg, Fe, Cu, and Zn contents than shoot. 3. Soil pH and Ca content of the natural habitats were higher, but the contents of P$_2$O$_{5}$, K, Mg, Na and organic matter were lower than those of the average soil in Korea. The soil texture of natural habitats showed much higher portion of sand and extremely low portion of silt and clay 4. Korean lespedeza is well adapted to soils so low in fertility and organic matter that other crops and most weed fail. also it appears to thrive on the loamy sands, sandy loams of the piedmont region and on similar soils with variously physico-chemical properties.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.1
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• pp.3-7
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• 1996

Effects of the nitrogen application time and amounts on the nitroger. uptake and recovery of fertilizer nitrogen applied at panicle formation stage was investigated in connection with the growth and yield of rice drill-seeded in puddle-soil. silt loam of Jeonbuk series. Urea was applied as nitrogen source. Nitrogen uptake and recovery of fertilizer nitrogen by rice plant was highest in the treatment applied nitrogen at 20 days before heading. Culm length, internode length (4th and 5th) and lodging index were increased by earlier application time and higher level of nitrogen. but filled grain ratio and 1,000 grain weight showed the opposite trend Panicle number per square meter and grain number per panicle was significantly decreased in nitrogen application at 10 days before heading. Rice yield was the highest in 33kgN/ha(conventional amount at 20days before heading, and yield in 26kgN/ha(80% of conventional amount) at 20 days before heading and in 33kg/ha at 15days before heading were nearly the same as conventional treatment.

• Korean Journal of Soil Science and Fertilizer
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• v.4 no.2
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• pp.187-192
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• 1971

This paper deals mainly with the genesis and classification of the Jeonnam series. These soils have brown to dark brown silt loam and silty clay loam A horizon(strong brown or reddish brown where eroded). Argillic B horizons are dominantly red or yellowish red silty clay loam to silty clay with moderately developed subangular blocky structure and with thin clay cutans on the ped faces. The C horizons are strongly and very deeply weathered strong brown, yellowish brown, pale brown and reddish yellow silty clay loam and sandy loam granitic saprolite. Content of clay increases with depth to a maximum between 100cm. Percolating water seems to be responsible for transportation and oriented deposition of clay. Chemically, soil reaction is strongly acid to medium acid throughout the profile. The content of organic matter is 1 to 2 percent, and decreases regularly with depth. Base saturation is low, based on amount of extractable cations. Characterisltically the Jeonnam series are similar to Red-Yellow Podzolic soils of the United States and are similar to Red-Yellow soils of the Japan. In the writer's opinion the Jeonnam soils are classified as Red Yellow soils. According to USDA 7th approximation, this soil can be classified as Typic Hapludults and in the FAO/UNESCO World Soil Map as Helvic Acrisols.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.2 no.2
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• pp.155-160
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• 1969

The soil textures and chemical compositions of Tapes Philippinarum beds were investigated in order to estimate the grade of the habitat soil of T. Philippinarum for the improvement of natural tidal flats. The coefficients of correlation between tile percentages of debris, coarse sand, fine sand, silt, and clay of the habitat soil, and the population density of T. Philippinarum were 0.78, 0.73, -0.42, -0.68, and -0.51 respectively. And the optimum levels of same were above $13.5\%,\;above\;23.0\%\;below\;41.5\%,\;below\;10.0\%$, and below $6.8\%$ respectively The $SiO_2\;Al_2O_3+Fe_2O_3$ ratio of the soil of T. Philippinarum beds showed the range of 5.09 to 5.60. The levels of soil pH, water holding capacity, organic matter, total nitrogen, available phosphorus, exchangeable magnesium were 6.15-6.60, $4.26-6.86\%$, $0.40-1.10\%$ 14.0-27.0 ppm, $0.041-0.394\%,\;and\;0.009-0.132\%$ respectively.