• Journal of the Korean Geotechnical Society
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• v.40 no.3
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• pp.93-100
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• 2024

Pore water freezes in low-temperature compaction, which leads to different compaction characteristics compared to room temperature conditions. In regions like Alberta, Canada, where organic soils are prevalent, compaction performance is influenced by the high water retention and compressibility of organic soils, as well as their sensitivity to freezing and thawing. Alberta's strict environmental regulations demand the reuse of excavated soil for backfill, and the long winter season creates challenging conditions for civil engineering projects. In this study, a laboratory compaction test was conducted to evaluate the low-temperature compaction characteristics of organic soils with varying organic content. The results indicate that the optimum moisture content increases as the organic content increases, and the maximum dry unit weight decreases by up to 21.9%. In addition, under temperature conditions below -4℃, no optimum moisture content was observed, and the dry unit weight decreased as the moisture content increased.

• Journal of Korean Society of Forest Science
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• v.38 no.1
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• pp.46-54
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• 1978

In afforestation of denuded forest land soil conditions play a very important role in early growth of cover vegetations. This study was designed for understanding the effect of soil moisture regime on growth and nutrient uptake of some seedlings. Cover vegetations such as Pinus rigida Miller, Robinia pseudoacacia L. and Lespedeza bicolor Turcz. were planted in pot with the soil transported from denuded forest land in Musu-ri Sannae-Myeon. Daedeog-Kun, Chungnam Province. There were 3 moisture treatments and 4 fertility levels in $P_2O_5$ with 4 replications. Influence on growth was observed by the variation in dry weight and nutrient uptake was studied in nitrogen, phosphate and kalium. Results are as follows: 1. For Pinus rigida seedlings decrease in soil moisture tension increases growth of dry weight and enhance the uptake of kalium. Increase in $P_2O_5$ fertility level tends to decrease the uptake of kalium rather than increase in $P_2O_5$ uptake. 2. In Robinia pseudoacacia increase in soil moisture content stimulates the uptake of nitrogen and kalium. Increase in $P_2O_5$ level enhances the uptake of $P_2O_5$ and increases growth of dry weight. 3. In Lespedeza bicolor increase in soil moisture content has a tendency of decrease in nitrogen uptake. Increase in $P_2O_5$ level increases the growth of dry weight as well as the uptake of $P_2O_5$.

• Korean Journal of Microbiology
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• v.21 no.1
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• pp.7-14
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• 1983

In order to study the effects of cropping system and fungicide (Dachigaren) on soil microbes, the seasonal fluctuations of soil microbes in the fields of radish and Chinese cabbage including soil pH, Soil moisture content and soil temperature were investigated on every 15 day interval from the begining of March to late October in 1981. The population of total fungus peaked at the begining of July, while that of total bacteria, at the begining of August. They were affected by soil temperature, however pathogenic microbes seemed to be more related with host plants than the soil temperature, because pathogens showed high density through the whole cultivation period. The pathogenic microbes showed the density of order ; Xanthomonas, Erwinia, Pseudomonas, Agrobacterium and Corynebacterium. Xanthomonas, Erwinia and Pseudomonas, which induced radish and Chinese cabbage diseases were higher than Agrobacterium and Corynebacterium in population densigy. Bacterial soft rot occured at the density of Erwinia $5.9{\sim}6.6{\times}10^5/dry$ soil 1 gram. The density of microbes on continuous fields were higher than that of rotating fields, but there were no significant difference between treated fungicide plot and non treated in the density of microbes, also no difference between Chinese cabbage and radish growing fields.

• Geomechanics and Engineering
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• v.19 no.5
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• pp.435-445
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• 2019

A series of element tests with different drainage conditions and strain rates were performed on compacted unsaturated non-plastic silt in unconfined conditions. Soil samples were compacted at water contents from dry to wet of optimum with the degree of saturation varying from 24 to 59.5% while maintaining the degree of compaction at 80%. The tests performed were shear infiltration tests in which specimens had constant net confining pressure, pore air pressure was kept drained and constant, just before the shear process pore water pressure was increased (and kept constant afterwards) to decrease matric suction and to start water infiltration. In constant water content tests, specimens had constant net confining pressure, pore air pressure was kept drained and constant whereas pore water pressure was kept undrained. As a result, the matric suction varied with increase in axial strain throughout the shearing process. In both cases, maximum shear strength was obtained for specimens prepared on dry side of optimum moisture content. Moreover, the gradient of stress path was not affected under different strain rates whereas the intercept of failure was changed due to the drainage conditions implied in this study.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.5
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• pp.1-12
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• 2009

This research was initiated to investigate the revegetation characteristics under the seeding amount treatments of cool-season turfgrasses on the disturbed slope. 4 different seeding amounts of cool-season turfgrasses (0.0 $g/m^2$, 1.5 $g/m^2$, 3.0 $g/m^2$, 6.0 $g/m^2$) with the same seeding amounts of native woody (Rhus chinensis, Albizzia julibrissin) and herbaceous plants (Lotus corniculatus var. japonicus, Dianthus sinensis, Aster yomena) were treated with 3 replications on the experimental disturbed slope. Data such as soil hardness (mm), moisture content (%), surface coverage rate (%), the number of each germinating plant and plant height were analyzed. There were no statistic differences observed in the soil hardness and the soil moisture content while a significant difference was observed in the surface coverage rates. The surface coverage rates were higher in 3.0 $g/m^2$ and 6.0 $g/m^2$ plots compared to the rest two plots of cool-season turfgrasses. However, the emergence of native woody and herbaceous plants was relatively low in 3.0 $g/m^2$ and 6.0 $g/m^2$ plots of high seeding amounts of cool-season turfgrasses. This result indicated that high seeding amounts of cool-season turfgrasses could decrease the emergence of native woody and herbaceous plants. We concluded that 1.5 g~3.0 $g/m^2$ seeding amounts of cool-season turfgrasses was optimum level for the balanced emergence of cool-season turfgrasses, native woody and herbaceous plants in the viewpoint of the ecological disturbed slope revegetation.

• Korean Journal of Agricultural and Forest Meteorology
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• v.6 no.1
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• pp.18-23
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• 2004

This study was conducted to provide a national forest management method for natural Pinus densiflora forest stands in central South Korea based on growth characteristics and water relations. Average stand volume per hectare was 259.3㎥ in the pine study site. Basal area, volume, annual mean increment and periodic annual increment of DBH for 10 years at each slope aspect appeared to decrease as the aspect shifts from north to south. Stems per hectare showed the lowest value at the northern aspect. Maximum water potentials measured between 12 and 14 o'clock were analyzed by aspect and elevation. Water potential of pine decreased as the aspect changed from north to south, and water potential increased at lower elevations. Soil water content for the pine stands tended to decrease as the aspect shifted from north to south. Water potential and soil moisture content were highly correlated. Soil water deficits indicate that pines have a higher moisture requirement on the ridge and the southern aspect.

• Korean Journal of Plant Resources
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• v.32 no.5
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• pp.478-485
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• 2019

As environmentally sound agriculture emphasize gradually as well as the importance of environment, many studies on weed and soil nematode control of new concept which does not affect adversely environment are in progress. For this purpose, plant seeds which are representative weed species in field were selected and treated with microwave having generating capacity of $17.73kw/m^3$, and investigated germination rates of weed seeds and the number of soil nematode according to soil moisture contents, soil depth and irradiation times. The microwave effect on the germination rates was extremely high in soil moisture content of 40% and irradiation time over 40 seconds for irradiation time, while soil depth did not affect germination rate. In view of the results so far achieved, it seems that universal dispersed microwave system is effective for the control of weed seeds.

• Korean Journal of Agricultural Science
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• v.27 no.2
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• pp.95-100
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• 2000

This study was carried out to estimate the effect of forest fire on physical and chemical properties of soil. The forest fire was in April 1997 in pinus densiflora dominant forest at Chungju of Chungbuk. After forest fire, dead trees were not cut. Soil samples were collected at 0-5, 5-10, and 10-20cm soil depths in November 1998 from the burned and unburned sites. The analyzed factors were soil organic matter, total N, available P, exchangeable K, Ca, and Mg, and CEC, pH, bulk density, and moisture content. There was no forest floor in burned site, but unburned site has the forest floor of 4cm thick. There were no differences in soil organic matter, total N, available P, exchangeable K, Ca, and Mg, and CEC, pH, bulk density, moisture content in all soil depth, between burned and unburned sites, except in available P in 5-10cm soil depth. Forest fire had not changed the physical and chemical soil properties in this study. However, burning of vegetation and forest floor organic matter may have adverse influence on long-term site productivity.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.3
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• pp.203-213
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• 2017

This study investigated the changes in yields, antioxidant compounds, and antioxidant activities among 11 adzuki bean cultivars cultivated in a paddy field with somewhat poorly drained soil. The adzuki bean cultivars were cultivated in the paddy field from 2015 to 2016 in Milyang, Gyeongsangnam, Korea. Average soil moisture content was 16.5% in 2015 and 31.0% in 2016 at the experimental site during adzuki bean cultivation. As the soil moisture content increased, most of the adzuki bean cultivars showed deceases in stem height, first setting pod node, number of pods, 100 seed weight, and yield. Chungju-pat produced the greatest yields among the 11 cultivars in 2015 and 2016, whereas Hongeon had the smallest yields. Adzuki bean yields after paddy field cultivation was lower for all cultivars than for adzuki bean yields from the same cultivars after upland field cultivation. Chungju-pat and Chilbo-pat showed the smallest decreases in yields after paddy field cultivation, whereas Hongeon and Kumsil showed the greatest yield reductions. There were no significant differences in proximate composition. Some mineral components ($P_2O_5$, Ca, and Mg) were statistically different across cultivars. Chungju-pat had the highest Ca and Mg contents, but antioxidant components (polyphenol and flavonoids) and antioxidant activities (ABTS and DPPH) were highest in Saegil and lowest in Jungbu-pat. PCA and clustering analyses, based on the growth, yield, and antioxidant component measurements, performed to identify which variables contributed the most to separating adzuki bean cultivars or to grouping cultivars with similar characteristics. These analyses showed that the antioxidant components and antioxidant activities had the most influence on grouping cultivars together. Among the 11 cultivars, Saegil was statistically different from the other cultivars, but the other 10 cultivars were not significantly different under paddy field cultivation. Soil moisture content affected adzuki bean yield and antioxidant component contents. An increase in soil moisture led to a decrease in yield, but an increase in antioxidant components. These results provide information that will improve the selection of an appropriate adzuki bean cultivar for use in paddy fields.

• Journal of the Korean Geosynthetics Society
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• v.23 no.2
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• pp.53-62
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• 2024

Recently, development of non-traditional energy such as oil sands has been actively conducted in the cold region such as Canada. Frozen soil has different thermal and mechanical characteristics from general soil due to its high organic contents. This study evaluated the impact of organic matter content on the thermal and mechanical behavior of frozen soil samples collected from Alberta, Canada, and Gangwon Province, South Korea. As the organic content increases, the maximum dry unit weight decreases and the optimum moisture content increases in compaction tests. In uniaxial compression tests under frozen conditions, the strength of the frozen specimens increased as the temperature decreased. The strength of Canada soil sample increased with higher organic matter content at low temperatures. However, the strength of frozen soil was not significantly affected by organic matter content due to the complex behavior and unfrozen water content. Thermal conductivity tests showed higher thermal conductivity in frozen conditions compared to unfrozen conditions, due to the higher thermal conductivity of ice compared to water. These findings provide essential data for geotechnical design and construction in large-scale projects such as oil sands development in cold regions. Further research is needed to explore the impact of organic matter content on different types of frozen soils.