• Korean Journal of Agricultural and Forest Meteorology
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• v.10 no.2
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• pp.35-46
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• 2008

Soil moisture is one of the important components in hydrological processes and also controls the subsurface flow mechanism at a hillslope scale. In this study, time series of soil moisture were measured at a hillslope located in Gwangneung National Arboretum, Korea using a multiplex Time Domain Reflectometry(TDR) system measuring soil moisture with bi-hour interval. The Box-Jenkins transfer function and noise model was used to estimate spatial distributions of soil moisture histories between May and September, 2007. Rainfall was used as an input parameter and soil moisture at 10 cm depth was used as an output parameter in the model. The modeling process consisted of a series of procedures(e.g., data pretreatment, model identification, parameter estimation, and diagnostic checking of selected models), and the relationship between soil moisture and rainfall was assessed. The results indicated that the patterns of soil moisture at different locations and slopes along the hillslope were similar with those of rainfall during the measurment period. However, the spatial distribution of soil moisture was not associated with the slope of the monitored location. This implies that the variability of the soil moisture was determined more by rainfall than by the slope of the site. Due to the influence of vegetation activity on soil moisture flow in spring, the soil moisture prediction in spring showed higher variability and complexity than that in early autumn did. This indicates that vegetation activity is an important factor explaining the patterns of soil moisture for an upland forested hillslope.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.143-151
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• 2005

This paper presented a method to estimate the consolidation yield stress of compacted soil with an unsaturated soil mechanics, especially considering the effect of matric suction. Then two kinds of experiments were conducted. One is a series of static compaction tests to monitor the matric suction, and the other is a series of consolidation tests on compacted soil without soaking. The results indicate that it is possible to derive the distribution of matric suction on compaction curves and to hypothesize the changes of the void ratio depending on the matric suction in the consolidation tests. With this experimental results, a new method was introduced to estimate the consolidation yield stress of compacted soil including compaction curves.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.2
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• pp.81-85
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• 1989

The 113 soils representing the Jisan soil series (fine loamy, mixed, mesic fluventic Haplaquepts) as mapped in Korea were to characterize the Jisan soil throughout its official range which was the range of properties used to establish series limits. The samples were stratified according to master horizon designation for statistical analysis. The means in selected soil properties, horizon thickness, solum thickness, soil texture, clay content, pH, BSP, and horizon sequence, were within acceptable limits. The minimum values were considerably lower than the lower limits of the official ranges while the maximum values were above the allowable amount. The ranges of definition degree which mean the test of proper placement of any marginal limits were 0.687 to 0.929. Thus, Jisan series as mapped from other soil bodies in the field could be seen similarities and understood relationships among individuals.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.2
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• pp.88-99
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• 2007

Soil moisture is one of the essential components in determining surface hydrological processes such as infiltration, surface runoff as well as meteorological, ecological and water quality responses at watershed scale. This paper discusses soil moisture transfer processes measured at hillslope scale in the Gwangneung forest catchment to understand and provide the basis of stochastic structures of soil moisture variation. Measured soil moisture series were modelled based upon the developed univariate model platform. The modeling consists of a series of procedures: pre-treatment of data, model structure investigation, selection of candidate models, parameter estimation and diagnostic checking. The spatial distribution of model is associated with topographic characteristics of the hillslope. The upslope area computed by the multiple flow direction algorithm and the local slope are found to be effective parameters to explain the distribution of the model structure. This study enables us to identify the key factors affecting the soil moisture distribution and to ultimately construct a realistic soil moisture map in a complex landscape such as the Gwangneung Supersite.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.3
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• pp.199-205
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• 2008

This study was carried out to find out causes of high Ni content and characteristics of potential increase of Cu and Zn contents in the soils of Jeju area. Soil samples were collected from 4 series of Alfisols, 35 series of Andisols, 9 series of Entisols, 16 series of Inceptisols, and 1 series of Ultisols, respectively. Parent material (gravel) samples were also collected from the same sites where soil samples were taken. Both soil and parent material samples were analyzed for Ni, Cu, and Zn. The average Ni content of all the soil samples was $79.2mg\;kg^{-1}$, which was exceeded warning standard for Ni against the Soil Conservation Act in Korea, whereas that of Cu and Zn contents were lower than the warning standard for Cu and Zn. The difference of Ni, Cu and Zn content was not consistent depending upon soil color. Ni content in the soil samples from Entisols was particularly high, whereas that from the other soil orders was similar to each other. Cu and Zn contents in the soil samples were similar regardless of the difference in soil order. Ni content in Seongsan Formation(SSF), Cinder cone(C) and acicular Feldspar Olivine Basalt(FOB) was high, while that in Feldspar Basalt(FB) and Trachy Andesite lava(TA) was low. Ni content in the non-agricultural land was higher compared with that in the agricultural land, whereas Cu and Zn contents in the non-agricultural land were significantly lower than that of agricultural land. The topsoil/subsoil ratios for Ni content in most of the soil samples were less than 1, while that for total contents of Cu and Zn in many of the soil samples were larger than 1 indicating potential Cu and Zn accumulation in topsoil by artificial reasons.

• Korean Journal of Agricultural Science
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• v.49 no.2
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• pp.379-387
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• 2022

A large amount of the mineral nitrogen is necessary for crop growth. With the use of nitrogen fertilizers, agricultural yield has increased during the last few decades. However, at the same time, nitrate from the cultivated land can be a source of environmental pollution, especially in water systems. For nitrogen management, it is necessary to analyze the pattern of nitrogen movement in soil. In this study, nitrogen leaching in upland soils was evaluated using undisturbed lysimeters with different soil textures during sesame cultivation. The soil texture of the lysimeters was clay loam (Songjung series) and sandy loam (Sangju series) soils. Sesame was cultivated from May 25 to August 24 in 2020. The standard amount of NPK fertilizer (N-P₂O₅-K₂O = 2.9-3.1-3.2 kg·10 a^-1) was applied before sowing. The amount of nitrogen leaching was calculated by multiplying the nitrogen (NO₃-N + NH₄-N) concentration and the amount of water drained below 1.5 m soil depth. The water was drained through percolation into macropores in the clay loam lysimeter. In contrast, in the sandy loam lysimeter, water drained more slowly than in the clay loam lysimeter. There was a slight difference in the total amount of leachate during the cultivation period, but the amount of nitrogen leaching was high in sandy loam soil. During the sesame cultivation period, the amount of nitrogen leaching from clay soil was 5.64 kg·10 a^-1, and 10.70 kg·10 a^-1 for sandy soil. We found that there was a difference in leaching depending on the soil physical characteristics. Therefore, it is necessary to consider the characteristics of soil to evaluate the leaching of nitrogen.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.5
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• pp.393-398
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• 2009

This study was conducted to reclassify Yongdang series based on the second edition of Soil Taxonomy : A Basic System of Soil Classification for Making and Interpreting Soil Surveys. Morphological properties of typifying pedon of Yongdang series were investigated and physico-chemical properties were analyzed according to Soil Survey Laboratory Methods Manual. The typifying pedon of Yongdang series has dark reddish brown (5YR 2/3) silt loam Ap horizon (0~14 cm), dark brown (7.5YR 2/3) silt loam BA horizon (14~32 cm), dark brown (7.5YR 2/3) clay loam Bt horizon (32~57 cm), dark yellowish brown (10YR 4/6) silty clay loam Btx1 horizon (57~110 cm), and dark yellowish brown (10YR 4/6) silty clay loam Btx2 horizon(more than 110 cm). That occurs on gently sloping lava plain and is derived from baslt materials. The typifying pedon has an argillic horizon from a depth of 32 to more than 110 cm and a fragipan from a depth of 57 to more than 110 cm. That has a base saturation (sum of cations) of 35% or more at 75 cm below the upper boundary of the fragipan. That can be classified as Alfisol, not as Inceptisol. The typifying pedon has udic soil moisture regime, and can be classified as Udalf. That has a fragipan with an upper boundary within 100 cm of the mineral soil surface, and keys out as Fragiudalf. Also that meets the requirements of Typic Fragiudalf. That has 18% to 35% clay at the particle-size control section, and has thermic soil temperature regime. Yongdang series can be classified as fine loamy, mixed, thermic family of Typic Fragiudalfs, not as fine loamy, mixed, thermic family of Aquic Eutrudepts.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.2
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• pp.185-192
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• 1987

A green house experiment was conducted to find out the acetylene reducing and $N_2$-fixing activity from photosynthetic and aerobic heterotrophic nitrogen fixing microorganisms in submerged paddy soil under different agricultural locality, soil series, soil texture, soil type, and drainage condition in which samples taken from without nitrogen treatment plot of NPK trials on 16 sites of the farmer's field. The results obtained were summarized as follows: 1. The highest acetylene reducing activity was observed at 7 days after incubation in the light condition (photo synthetic microbes+heterotrophic bacteria) while it was observed at 35 days incubation in the dark condition (heterotrophic bacteria). 2. Among the soil series, photosynthetic nitrogen fixing activity was pronounced more in Jangae, Ogcheon and Hwadong series while lower was obtained in Buyong and Daejeong series. Aerobic heterotrophic nitrogen fixing activity was high in Buyong and Daejong series. 3. Estimated amount of $N_2$-fixation from acetylene reducing activity was equivalented to 3.0 mg in light condition and 4.9 mg/100g/105 days in dark condition. 4. Among the agricultural locality, photosynthetic nitrogen fixing activity was high in rather warm southern part while heterotrophic nitrogen fixing activity was predominated more in mountainous area and Chungcheong continental. 5. Photosynthetic nitrogen fixing activity was predominated in high productive soil while aerobic heterotrophic nitrogen fixing activity was pronounced more in crose coarse sandy soil. 6. The soils properties of high photosynthetic nitrogen fixing activity were constituted of poorly or imperfectly drained clay or clay loam soil while heterotrophic nitrogen fixing activity was pronounced more in well to moderately well drained sandy or sandy loam soil.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.129.2-130
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• 2003

Tomato soil pathogens(Phythopthora spp.) analyed high rates in series culture soil and existed in culture parts. To make a diagnosis of Phythopthora sp. and Its concentration, potato slices were manufactured to a round shape(2.5cm) or retangular form(1x4cm). and then, The potato slices dipped into diagnostic reagents with an antibiotic substance for 2∼4hours. Potato slices treated with a few reagents varied into 15cm depths in innoculated soils for 24hrs. Mycelium of the Phytophthora root rot fungus, Phythopthora capsici, were produced easily on potato slice. We collected many potato slice samples on diseased fields in various area. After storage of 24hrs in 20$^{\circ}C$ incubator, White mycelium of Phythopthora sp. formed on potato slice surface. Dilute concentrations of Phythopthora sp. was detected very low contents(1${\times}$10$^1$sporangia/g). But expressing Phythopthora root rots on potato slice did not developed larger lesions upon storage time in room temperature. These results suggest that the use of potato slice in a series of soil cultural system may still serve as efficient means of diagnosis of Phythopthora root rots in the absence of control measures.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.4
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• pp.278-283
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• 1993

Gimhae series has a high content of jarosite mineral which is evoluted in soils from sediments rich in sulfur. Chemical compositions of jarosite mineral and soil samples were analyzed with water and various extraction solutions to evaluate the pedogenetic processes of the soil. The pH of jarosite mineral and $Bg_3$ horizon are below 4.0 and not much changed after incubation of dry samples rich in jarosite. The pedogentic formation of jarosite was identified through the chemical analysis indicating that cations and anion of K, Na, Al and S are present in abandance in $Bg_2$ and $Bg_3$ horizons.