• Korean Journal of Weed Science
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• v.11 no.3
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• pp.224-228
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• 1991

This study was carried to know factors affecting emergence of major upland weeds in soil in order to get basic information on weed control methods. Firthy eight percent of weed seeds were distributed within soil surface to 10cm in soil and 2% of weed seeds were observed in 40~50cm soil layer in field. As planting depth was deeper, emergence of weeds became poor. However Capsella bursa-pastoris can emerge at soil surface. Amaranthus retroflexus, Amaranthus lividus, Porturaca oleracea, Chenopodium album, Solanum nigrum upto 3cm, Eleusine indica, Echinochloa crus-galli, Setaria viridis, Digitaria sanguinalis upto 7cm. Emergence of weeds was very poor in very acid soil but good in soil pH 5.5~6.0. However emergence of weed was not affected by pH 3.5~4.0 or above. Emergence of E. indica, C. bursa-pastoris, A. retroflexus, A. lividus, C. album, E. crus-galli, Solanum nigrum, and S. viridis was good in loam soil and P. oleranea, D. sanguinalis in sandy loam soil. Emergence of weed seeds was not affected by fertilization.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.296-313
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• 2014

A QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) multiresidue method was developed for the simultaneous analysis of 124 pesticides in soil by LC-MS. The procedure involved liquid extraction of soil immersed with 0.2N $NH_4Cl$ by acetonitrile with 1% acetic acid, followed by anhydrous $MgSO_4$ and sodium acetate, and dispersive SPE cleanup with $MgSO_4$, primary secondary amine (PSA) and $C_{18}$. The extracts were analyzed with LC-MS/MS in ESI positive mode. Standard calibration curves were made by matrix matched standards and their correlation coefficients were higher than 0.99. Recovery studies for the validation were carried out using two type soils, loam and sandy loam, at four concentration levels (0.005, 0.01, 0.02, and 0.1 mg/kg). The recoveries of pesticides were in the range of 70-120% with < 20% RSD except 4 pesticides, Benfuracarb, Ethiofencarb, Pymetrozine, and Pyrethrin. This result indicated that the method using QuEChERS and LC-MS/MS could be applied for the simultaneous determination of pesticide residues in soils.

• The Korean Journal of Quaternary Research
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• v.17 no.2
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• pp.163-163
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• 2003

The study area, Kwangneung Experiment Forest (KEF) is located on the west-central portion of Korean peninsula and belongs to a cool-temperate broadleaved forest zone. At the old-growth deciduous forest near Soribong-peak (533.1m) in KEF, we have established a permanent plot and a flux tower, and the site was registered as a KLTER site and also a KoFlux site. In this study, we aimed to present basic ecological characteristics and synthetic data of carbon budgets and flows, and some monitoring data which are essential for providing important parameters and validation data for the forest dynamics models or biogeochemical dynamics models to predict or interpolate spatially the changes in forest ecosystem structure and function. We made a stemmap of trees in 1 ha plot and analyzed forest stand structure and physical and chemical soil characteristics, and estimated carbon budgets by forest components (tree biomass, soils, litter and so on). Dominant tree species were Quercus serrata and Carpinus laxiflora, and accompanied by Q. aliena, Carpinus cordata, and so on. As a result of a field survey of the plot, density of the trees larger than 2cm in DBH was 1,473 trees per ha, total biomass 261.2 tons/ha, and basal area 28.0 m2/ha. Parent rock type is granite gneiss. Soil type is brown forest soil (alfisols in USDA system), and the depth is from 38 to 66cm. Soil texture is loam or sandy loam, and its pH was from 4.2 to 5.0 in the surface layer, and from 4.8 to 5.2 in the subsurface layer. Seasonal changes in LAI were measured by hemispherical photography at the l.2m height, and the maximum was 3.65. And the spatial distributions of volumetric soil moisture contents and LAIs of the plot were measured. Litterfall was collected in circular littertraps (collecting area： 0.25m2) and mass loss rates and nutrient release patterns in decomposing litter were estimated using the litterbag technique employing 30cm30cm nylon bags with l.5mm mesh size. Total annual litterfall was 5,627 kg/ha/year and leaf litter accounted for 61% of the litterfall. The leaf litter quantity was highest in Quercus serrata, followed by Carpinus laxiflora and C. cordata, etc. Mass loss from decomposing leaf litter was more rapid in C. laxiflora and C. cordata than in Q. serrata litter. About 77% of C. laxiflora and 84% of C. cordata litter disappeared, while about 48% in Q. serrata litter lost over two years. The carbon pool in living tree biomass including below ground biomass was 136 tons C/ha, and 5.6 tons C/ha is stored in the litter layer, and about 92.0 tons C/ha in the soil to the 30cm in depth. Totally more than about 233.6 tons C/ha was stored in DK site. And then we have drawn a schematic diagram of carbon budgets and flows in each compartment of the KEF site.

• Analytical Science and Technology
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• v.31 no.5
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• pp.185-194
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• 2018

At the end of November 2010, livestock infected with foot and mouth disease (FMD) were buried, increasing concern about secondary pollution of drinking water and groundwater with odor. Hence, measures to reduce pollution of drinking water and groundwater are needed. In this study, based on livestock type and soil texture, five pilot-scale burial sites were monitored for the past three years from Feb 2012 to 2015. Leachate from the site was analyzed for 90 compounds. A detailed investigation has been completed, looking into organic matter decomposition characteristics of the buried bodies, relevant trace elements thereof, and in particular metabolite concentration changes such as the degree of decomposition of a carcass. From the results, no detectable heavy metals, including cadmium and arsenic, were measured. Among animal types, the rate of cattle decomposition is faster than swine decomposition, and the decomposition of the bodies were performed in sequence from sand, clay loam, sandy loam.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.4
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• pp.3931-3942
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• 1975

This study was conducted to investigate the strength of soil cement for varied curing temperatures (0,10,20,30,40,50,60$^{\circ}C$) and cement content (3,6,9,12%) in four cement-stabilized soils (KY: sand, MH: sand, SS: sandy loam, JJ:loam). The experimental results obtained from unconfined compressive strength tests were as follows: 1. According to increase of curing temperature as 30,40,50, and 60$^{\circ}C$, the unconfiened compressive strength of soil cement increased, the rate of increase in the early curing period was large, and around 120 hours was suifficient curing time to complete hardening. 2. The strength at 10$^{\circ}C$ decreased to the rate of 30 to 40 percent than that of 20$^{\circ}C$ while the strength at 0$^{\circ}C$ was very small, strength of soil cement increased in cold weather unless that the temperature was below 0$^{\circ}C$ 3. The average maximum temperature, about 30$^{\circ}C$ during July and August in Korea may be recommended for a optimum construction period to increase the strength of soil cement. 4. Accelerated curing time that strength was equivalent to 28-Day norma1 curing decreased in accordance with the increase of curing temperature, and also accelerated curing decreased the effect of cement content. Accelerated curing that strength was equivalent to 28-day normal curing for soil cement of cement content 9% and temperature 60$^{\circ}C$ was 45 hours; KY, 50 hours: MH, 40 hours; SS, 34 hours; JJ. 5. According to the increase of the percent passing of No. 200 sieve, accelerated curing times became shorter to become the required stength. 6. Relation between accelerated curing times and normal curing days was showeda linear of which slope decreased in accordance with the increase of curing temperature, it may be expressed as follows: (1). 30$^{\circ}C$ t=3.6d+6(r=0.97) (2). 40$^{\circ}C$ t=3.2d-5.1(r=0.95) (3). 50$^{\circ}C$ t=2.1d-4.0(r=0.93) (4). 60$^{\circ}C$ t=1.4d+4.0(r=0.90) in which t=accelerate curing time. d=normal curing day. 7. Accelerated curing time that the strength was equivalent to 35kg/$\textrm{cm}^2$ which was the strength of cement brick was 96 hours at temperature 30$^{\circ}C$ to SS 9%, and 120 hours at temperature 50$^{\circ}C$ to JJ 9%, Consequently, a economic soil cement brick may be made in future.

• Korean Journal of Weed Science
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• v.14 no.4
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• pp.280-290
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• 1994

The germination and the nutrient culture tests in the growth chamber and pot experiment under two types of soil conditions were conducted to determine the selectivity of oxyfluorfen and chlormethoxynil in crops and weeds and for characterization of selective mode of action, the absorption study was also conducted with different absorption methods and application time using $^{14}C$-oxyfluorfen. Oxyfluorfen showed more growth inhibitory effects than chlormethoxynil. In the nutrient culture test, rice growth was greatly inhibited at 2-leaf stage than at 4-leaf stage, and the shoot parts were more inhibited than the root parts. By preemergence application of both herbicides, higher growth inhibition was observed in sandy loam soil than in clay loam soil. Absorption and translocation of $^{14}C$-oxyfluorfen were higher by foliar application than by root treatment, and selectivity of crops and weed species may be explained partly by the amount of absorption.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.2
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• pp.187-193
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• 2011

RDA has been conducting soil survey for farmland all over the korean countries (1964-1999), including small islands and areas of the civilian passage restriction line (2000-present). We conducted a soil survey in Dokdo and Ulreungdo islands and found a new soil series "Dokdo" in Dokdo island. Soil properties of Dokdo were similar to those of Ulreungdo. Representative profiles of Dokdo soil was located at the south 20m of Daehan peak on Seodo (longitude $131^{\circ}$51'53", latitude $37^{\circ}$14'35"), Dokdo. The soil series "Dokdo" was interpreted as the soils were derived from trachyandesite, trachyte, rhyolite, and tuff. The soil properties of Dokdo series were classified as different ones from Korean soil series previously. The soil depth of Dokdo series was very shallow (0-20cm) and soil layer was consisted of very dark brown (10YR 2/2) rocky sandy loam and dark brown (7.5YR 3/2) gravelly silt loam in AC layer. The soils of Dokdo displayed characteristics of a mesic temperature regime, similar as Ulreungdo soils, which were classified as coarse loamy, mesic family of Lithic Udorthents. The total area of Dokdo soil was 18.7 ha, containing Dongdo (7.3 ha), Seodo (8.9 ha), and the others (2.6 ha). The area of Dokdo series in Dokdo was 10.47 ha (Dongdo 4.13 ha, Seodo 6.34 ha) and 808.56 ha in Ulreungdo, where the total soil area was 7,256 ha.

• Korean Journal of Agricultural Science
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• v.42 no.1
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• pp.15-22
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• 2015

This study was conducted to evaluate the phytotoxicity of imazosulfuron+fentrazamide mixture in rice field. It is recommended that safe herbicide application was obtained at 3 cm of transplanting depth and in sandy loam or loam soil type. In the direct water seeding of rice, imazosulfuron+fentrazamide SC should be applied at least 10 days before sowing land ower than 25+100 g ai/ha. In case of imazosulfuron+fentrazamide SC application after sowing, If we use the herbicide 15 days after sowing, no herbicide symptoms will be detected even though the amounts of the herbicide increase. In the rice transplanting, it is recommended that imazosulfuron+fentrazamide GR is applied 5 days after transplanting. In case of sequential herbicide application, the imazosulfuron+fentrazamide SC application at 75+300 g ai/ha 15 or 20 days after transplanting after the application at 25+100 g ai/ha or 50+200 g ai/ha 3 days before sowing increases weed control efficacy and gives no phytotoxicity in the rice growth.

• The Korean Journal of Ecology
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• v.24 no.2
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• pp.101-109
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• 2001

We created an environmental forest on the basis of ecological design around the incineration plant of Jindo Engineering and Construction Co., Ltd., which is located in Jeongwang-dong, Siheung-si, Kyunggi-do. To get ecological information of this site, physico-chemical properties of soil on salt marsh, which is located close to the syudy site and of forest soil transported from other sites for ecological restoration were analyzed. Texture of salt marsh and transported soils were loam and sandy loam, respectively. pH, organic matter, T-N, available P, and exchangeable K and Na contents of salt marsh and transported forest soils were 6.7 and 5.4, 4.1 and 0.4%, 1.0 and 0.3mg/g, 46.7 and 6.8ppm, 521 and 207ppm, and 3.8 and 0.5mg/g, respectively. Introduced plants were selected among the dominant species of forests and the species composing the potential natural vegetation around the present study site. Those plants were selected again by considering the tolerances to air pollution and to salt, and their availability. Selected trees were Pinus thunbergii, Sophora japonica, Celtis sinensis, Quercus aliena, Q. serrata, Q. dentata, and Q. acutissima. Selected sub-trees were Albizzia julibrissin, Koelreuteria poniculata, and Styrax japonica and shrubs were Rhododendron yedoense var. poukhanense, R. mucronulatum, Callicarpa japonica, Euonymus alatus, E. japonica, and R. schlippenbachii. On the other hand, introduction of herbs was not considered except for Liriope platyphylla, which was ornamentally planted in one site. Planting bed of mound type was adopted to provide the fine drainage system. Mound was designed to furnish litter, A, B, and C layers simuating the profile of forest soil. Slope of mound was mulched by rice straw of 2cm in thickness to prevent for sliding of litter and soil in cases of strong wind or heavy rain. Height of mound was designed to secure more than 1 m by combining A and B layers. Narrow zones, in which mound with stable slope degree cannot be prepared, was designed to equip the standard soil depth with the introduction of stone for supporting. On the other hand, plants with shallow root system were arranged in some zones, in which satisfactory soil depth cannot be ensured. Plants were arranged in the order of tree, sub-tree, and shrub from center to edge on the mound to make a mature forest of a dome shape in the future. Dispersion of plants was designed to be random pattern rather than clumped one. Problems on creation of the environmental forest by such ecological design were found to be management or inspection by non-specialized project operators and inspecting officers, and regulations for construction without ecological background. Alternative plans to solve such problems were suggested.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.299-299
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• 2017

Due to the climate changes in Korea, the numbers of both torrential rain events and drought periods have increased in frequency. Water management practice against water shortage and flooding is one of the key interesting for field crop cultivation, and groundwater often serves as an important and safe source of water to crops. Therefore, the objective of this study is to evaluate the effect of groundwater table levels on soil water content and soybean development under two different textured soils. The experiment was conducted using lysimeter located in Miryang, Korea. Two types of soils (sandy-loam and silty-loam) were used with three groundwater table levels (0.2, 0.4, 0.6m). Mean soil water content during the soybean growth period was significantly influenced by groundwater table levels. With the continuous groundwater level at 0.2m from the soil surface, soil water content was not statistically changed between vegetative and reproductive stage, but the 0.4 and 0.6m groundwater table level was significantly decreased. Lower chlorophyll content in soybean leaves was found in shallow water table treatment in earlier part of the growing season, but the chlorophyll contents were non-significant among water table treatments. Groundwater table level treatments were significantly influenced on plant available nitrogen content in surface soil. The highest N contents were observed in 0.6m groundwater table level. It is probably due to the nitrogen loss by denitrification as the result of high soil water content. The length and dry weight of primary root was influenced by groundwater level and thus the highest length and dry weight of root were observed in 0.6m water table level. This result showed that soybean root growth did not extend below the groundwater level and increased with the depth of groundwater table level. The results of this study show that the management of groundwater level can influence on soil characteristics, especially on soil water content, and it is an important practice of to reduce yield loss caused by the water stress during the crop growing season.