• Korean Journal of Environmental Agriculture
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• v.26 no.4
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• pp.343-350
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• 2007

Three different experiments were carried out to investigate the runoff and erosion losses of endosulfan from sloped-field by rainfall. The mobility of endosulfan and which phase it was transported by were examined in adsorption study, the influence of rainfall pattern and slope degree on the pesticide loss were evaluated in simulated rainfall study, and the pesticide losses from soybean-grown field comparing with bare soil were measured in field lysimeter study. Adsorption parameter (K) of endosulfan ranged from 77 to 131 by adsorption method and K values by the desorption method were higher than those by the adsorption method. By the SSLRC's classification for pesticide mobility endosulfan was classified as non-mobile class ($K_{oc}>4,000$). Runoff and erosion loss of endosulfan by three rainfall scenarios ranged from 3.4 to 5.6%and from 4.4 to 15.6%of the amount treated. Endosulfan residues were mainly remained at the top 5 cm of soil depth after the simulated rainfall study. Pesticide loss in case of 30%-slope degree ranged from 0.6 to 0.9 times higher than those in case of 10%-slope degree. The difference of pesticide runoff loss was related with its concentration in runoff water and the difference of pesticide erosion loss would related closely with the quantity of soil eroded. Endosulfan losses from a series of lysimeter plots in sloped land by rainfall ranged from 5 to 35% of the amount treated. The erosion rate of endosulfan from soybean-plots was 66% of that from bare soil plots. The effect of slope conditions was not great for runoff loss, but was great for erosion loss as increasing to maximum $4{\sim}12$ times with slope degree and slope length. The peak runoff concentration of endosulfan in soybean-plots and bare soil plots ranged from 8 to 10 and from 7 to $9{\mu}gL^{-1}$ on nine plots with different slope degree and slope length. Therefore the difference of the peak runoff concentrations between bare soil plots and soybean-plots were not great.

• Korean Journal of Weed Science
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• v.17 no.3
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• pp.269-280
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• 1997

Collated data from the 1995-1996 field surveys of weed seeds buried in the plough layer of peat soil in Selangor district were analysed to assess species-dominance and spatial pattern of distribution of weed seeds based on selected quantitative indices and index of dispersion. Forty five species within 14 families were recorded of which 24 were broadleaves, 12 grasses and 9 sedges. They comprised ca. 53.2, 31.2 and 15.6%, respectively based on total population counts. Total seed population was ca. $8.14{\times}10^7$ seeds/ha within the fast 25cm soil depth. Wide variabilities in population counts were registered among species ranging from < $7.0{\times}10^4$ seeds/ha for Amaranthus gracilis to ca. $5.64{\times}10^6$ seeds/ha for Heteropogon contortus. Seeds of Cleome rutidesperma was the most abundant(ca. $2.347{\times}10^7$ seeds/ha). Difference in seed population counts may be attributed to inherent variation in fecundity, population fluxes, their spatial distribution patterns and the agronomic practices prevailing in the areas of survey. The profile distribution of soil seed banks was skewed within the first 0 - 10cm depth, comprising ca. 69% of the total seed counts. Seed counts in the 10 - 15, 15 - 20 and 20 - 25cm soil profiles were in the order of 17.9, 8.6 and 4.0% of the total populations, respectively. Weed seeds of all species displayed different degree of aggregated pattern of distribution with variance-to-mean ratios of > 1 and Lloyd's mean crowding($m^*$) values from 1.244 for Cyperus iria, Phyllanthus debilis, Phyllanthus urinaria, Scirpus grosses and urinaria lagopodiodes to 9607.7 for Cleome rutidosperma. Lloyd's patch indices(Ip) ranging from 5.1 for Aeschynomene indica to 188.5 for Bracharia reptans were registered. Differences in the VMR, $m^*$ and Ip values among species suggested inter-alia inherent variabilities in their disposal capacity from seed source and different agronomic practices prevailing in the areas surveyed.

• Korean Journal of Soil Science and Fertilizer
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• v.4 no.1
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• pp.79-85
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• 1971

The rice variety, Kwanok, was reared in the water, land and salty beds and transplanted to the reclaimed soil area having an average of 0.48% salt concentration 0.67% at the end of April Two levels of $NH_3$-N and urea-N with 6 treatments were used. The effect of each treatment was observed. The plant height of the land bed seedlings at transplanting stage was short but the dry-weight/plant-height ratio was large, and the rooting ability vigorous remarkably after transplantation in the salty area. The total carbohydrate content of the stem part was markedly larger in the land bed seedlings than the others and the C/N ratio was accordingly greater. This tendency was observed through the last rooting stage. In the salty nutrient solution, the roots of salty bed seedlings showed high respiratory activity. The activity of the land bed seedlings did not decreased in the hypertonic solution as much as the water bed seedlings. There was no difference in the effect of fertilization on the rough rice yield between ammonium sulphate and urea. The cultural practices with the land and salty bed seedlings increased the rough rice yields by 33% and 22% respectively, compared with the yields of the water bed Seedlings. The number of panicles, panicle weight and the number of grains per panicle were much greater from the rice plant grown by the land bed seedlings than from the other bed seedlings.

• Journal of Wetlands Research
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• v.25 no.3
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• pp.205-212
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• 2023

This study was attempted to find out how the ecological niche and interspecies relationship of Quercus aliena and Q. serrata, which are the main constituents of potential natural vegetation along the riverside of mountains in Korea, under climate change conditions. To this end, soil moisture and soil nutrients were treated with 4 grad ients under climate change conditions with elevated CO₂ and temperature, plants we re harvested at the end of the growing season, growth responses of traits were measured, ecological niche breadth and overlap were calculated, and it was compared with that of the control group(ambient condition). In addition, the relationship between the two species was analyzed by principal component analysis using trait values. As a result, the ecological niche breadth of Q. aliena was wider than that of Q. serrata under the moisture environment conditions under climate change. Under nutrient conditions, the ecological niche of the two species were similar. In addition, the ecological overlap for soil moisture of Q. aliena and Q. serrata was wider than the soil nutrient gradient under climate change. The species with traits in which the increase in ecological niche breadth due to climate change occurred more than the decrease was Q. aliena in both water and nutrient gradients. And in the responses of the population level, due to climate change, the adaptability of Q. aliena was higher than that of Q. serrata under the soil moisture condition, but the two species were similar under the nutrient condition. These results mean that the competition between the two species occurs more severely in the water environment under climate change conditions, and at that time, Q. aliena has higher adaptability than Q. serrata.

• Journal of Animal Environmental Science
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• v.10 no.1
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• pp.47-58
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• 2004

This work was carried out to investigate the effects of rice hull continuously utilized and/or replenished on the composting properties and to obtain the fundamental data between an unsupported wall and a soil supported wall during the period of composting with pig slurry in winter season. There were no the temperature holding effects in soil supported wall. New compost facility design for the temperature holding effects from a soil supported wall was required. The results were as follows; 1. Composting 1㎥ of pig slurry caused to save on 0.31㎥ of bulking agent in the unsupported wall in comparison with a soil supported wall in the rice hull single addition, and 0.45㎥ in the rice hull gradual addition. 2. The pile in the rice hull single addition had a high temperature in 4 days of composting indicating $71^{\circ}C$ and had a tendency in repeating periodically between $40^{\circ}C$ and $65^{\circ}C$ till 43 days of composting. And also the temperature of the pile was maintained between $48^{\circ}C$ and $28^{\circ}C$ after 50 days of composting. The pile of a rice hull gradual addition had the lower point of the temperature high increasingly according to adding up rice hull during the 35 days of composting. 3. The pH recorded in the rice hull single addition was higher(8.35∼10.02) compared to the rice hull gradual addition(8.6∼9.8). The pile of a rice hull single addition had a tendency in abruptly decreasing pH of the unsupported wall during the period of between 0.363$\textrm m^3$ and 0.537$\textrm m^3$ as a unit of pig slurry per rice hull. EC depending upon the way in adding rice hull was changed between 1.10 mS/$\textrm {cm}^3$ and 1.87 mS/$\textrm {cm}^3$. 4. The organic matter in an unsupported wall of the hull single addition was maintained the level of 55% during the period between 0.119㎥ and 0.363㎥ as a unit of pig slurry per rice hull while in the soil supported wall between 48 and 70. Water soluble C:N ratio was maintained between 1 and 2 in the rice hull single addition, while between 1 and 3 in the rice hull gradual addition. 5. Fertilizer constituents were detected higher level in the unsupported wall than in the soil supported wall in all treatments. This was dependant upon the input of pig slurry.

• Korean Journal of Environmental Agriculture
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• v.32 no.4
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• pp.273-278
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• 2013

BACKGROUND: Total petroleum hydrocarbons (TPH), which are main materials of soil contamination by oil, are a term used for any mixture of hydrocarbons. Korea Ministry of Environment established the maximum permissible level of TPH in farmland by 500 mg/kg, and reported that the TPH level of soil in 266 installation such as gas station, transport company, and military unit ranged from 1,356 to 55,117 mg/kg and were much higher than the maximum permissible level in 2011. METHODS AND RESULTS: To determine the effect of TPH on crops, we investigated the effect of gasoline, kerosene, and diesel on the germination and radicle growth of mainly consumed crops. The germination rates of control in investigated all crops ranged from 80.0-100%. The germination and radicle growth in majority of investigated crops were not inhibited even at 2,500 mg/L. However, germination in onion, leek, and green perilla and radicle growth in leek, rape, tomato, and green perilla were significantly inhibited by increasing concentrations of gasoline, kerosene and diesel treatment. Germination and radicle growth inhibition of green perilla by kerosene and diesel were the highest, the percent inhibition at the 500 mg/L were 100 and 98.6%, 100 and 88.2%, respectively. 50% inhibition of germination in green perilla by kerosene and diesel were 39.96 and 29.87 mg/L, and 50% inhibition of radicle growth were 52.76 and 177.96 mg/L, respectively. Conclusion(s): These results suggest the possibility that the maximum permissible level of TPH might to be established general level with exception by crops.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.236-246
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• 2014

Pesticide is used to protect the crops, but also become a cause of polluting the environment. Perform a risk assessment using physical and chemical properties, environmental fate and toxicity data in order to determine the pesticide registration. The aquatic model estimates pesticide concentrations in water bodies that result from pesticide applications to rice paddies and apple orchard. The used models are the PRZM, EXAMS and AGRO shell (PA5), Rice Water Quality Model (RICEWQ) and Screening Concentration In GROund Water (SCI-GROW). The residual concentration of water body was estimated using meteorological data, crop calendar and soil series of Korea. The chosen pesticides were butachlor, carbofuran, iprobenfos and tebuconazole. It has shown the potential that the RICEWQ is possible to predict residue level in water of butachlor and iprobenfos, because the maximum value in water monitoring data is lower than the peak concentration of the model, and the minimum value is lower than the average annual concentration of the model. But RICEWQ was insufficient to predict exposure concentrations in ground water. The estimated exposure concentrations of carbofuran in ground water is very higher than in surface water because of its low soil adsorption coefficient. Although tebuconazole were not detected in the water monitoring that means very low concentration, it is possible that the PA5 can be used to predict residue level in water.

• Korean Journal of Agricultural Science
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• v.20 no.2
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• pp.145-152
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• 1993

Vegetational data obtained from 15 quadrats of Mt. Daeam area were analysed by applying two multivariate methods : two-way indicator species analysis(TWINSPAN) for classification and detrended canonical correspondence analysis(DCCA) for ordination. The dominant tree species were Quercus mongolica, Acer pseudo-sieboldianum, Betula costata, and Acer mono in descending order. The pH ranges were 5.0 to 5.5 in the 15 sites near bog and 5.3 to 5.4 in the 3 sites within bog. The forest communities in Mt. Daeam were classified into Quercus mongolica-Acer mono, Quercus mongolica-Prunus sargentii, Quercus mongolica-Abies nephrolepis-Acer tschonoskii var, rubripes, and Quercus mongolica-Abies nephrolepis-Betula costata according to the TWINSPAN. The relationships between the distribution of dominant species of forest vegetation and soil in the forest of Mt. Daeam were investigated by analyzing soil nutrition gradient. Quercus mongolica-Prunus sargentii forests were distributed in the good sites in nutrition levels of total nitrogen, cation exchange capacity, $Mg^{+{+}}$ and $Ca^{+{+}}$ but Quercus mongolica-Abies nephrolepis-Betula costata forests in the poor sites in the nutrition levels.

• Korean Journal of Weed Science
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• v.30 no.3
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• pp.252-257
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• 2010

The experiments were carried out to develop ecological weed control system in wheat field of rice-wheat cropping system. The results were, depression effect on water foxtail by wheat seeding method decreased the seeding after doing soil rotary by 85% compared with the no practices. The occurrence of Water foxtail was 40 piece $m^{-2}$ on October 16, 29 piece $m^{-2}$ on October 26, and 4 piece $m^{-2}$ when surveying based on the standard of seeding the wheat at 15kg $ha^{-1}$ which decreased as the seeding time got later. According to the wheat seeding quantity 29 piece $m^{-2}$ occurred at 150kg $ha^{-1}$, and 8-11 piece $m^{-2}$ decreasingly at more than 200 kg $ha^{-1}$ of wheat seedlings based on seeding on October 26. As a result of summarizing the above results, crushing the soil by use of rotary before seeding wheat against the end of October, and seeding by increasing the seedling quantity (200 kg $ha^{-1}$) it is judged that the competition damage by weeds including water foxtail can be reduced without any use of herbicide.

• Journal of Korea Water Resources Association
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• v.49 no.8
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• pp.685-692
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• 2016

This study aimed to develop the indicator-based approach to assess water use vulnerability in watersheds and applied to the unit watershed within the Han River watershed. Vulnerability indices were comprised of three sub-components (exposure, sensitivity, adaptive capacity) with respect to water use. The indicators were made up of 16 water use indicators. Then we estimated vulnerability indices using the Technique for Order of Preference by Similarity to Ideal Solution approach (TOPSIS). We collected environmental and socio-economic data from national statistics database, and used them for simulated results by the Soil and Water Assessment Tool (SWAT) model. For estimating the weighted values for each indicator, expert surveys for subjective weight and data-based Shannon's entropy method for objective weight were utilized. With comparing the vulnerability ranks and analyzing rank correlation between two methods, we evaluated the vulnerabilities for the Han River watershed. For water use, vulnerable watersheds showed high water use and the water leakage ratio. The indices from both weighting methods showed similar spatial distribution in general. Such results suggests that the approach to consider different weighting methods would be important for reliably assessing the water use vulnerability in watersheds.