• Korean Journal of Ecology and Environment
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• v.35 no.3 s.99
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• pp.152-159
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• 2002

The seasonal variations of nitrifying bacterial population sampled from 3 sites in Moon-Chon reservoir were analyzed by in situ hybridization with fluorescently labeled rRNA-targeted oligonucleotide probes from August 2000 until July 2001. In addition, physico-chemical parameters such as temperature, pH, chi-a and DOC were measured to determine correlations between those factors and the size of nitrifying bacterial populations. Total bacterial numbers varied in the range of $0.8{\sim}1.5{\times}10^6\;cells/ml$ independent of sites and had the maximal values in March at all 3 stations. The ratio of eubacteria to total bacteria ranged from 44.9% to 79.5%, and the ratio of each nitrifying bacteria to eubacterial numbers reached only $1.0{\sim}7.4%$. The variations of ammonia-oxidizing bacteria ranged from $1.1{\times}10^4$ to $3.0{\times}10^4\;cells/ml$ without noticeable peak values whereas those of nitrite-oxidizing bacteria varied in $1.3{\sim}5.7{\times}10^4\;cells/ml$ with the increasing tendency in winter regardless of the sites. Moreover it was observed that the numbers of nitrite-oxidizing bacteria were higher than those of ammonia-oxidizing bacteria. Total bacterial numbers correlated with water temperature (r = 0.355, p<0.05) and DOC (r = 0.58G, p<0.01) positively whereas nitrite-oxidizing bacteria correlated with temperature (r = -0.416, p<0.05) and pH (r = -0.568, p = 0.001) negatively. In addition, DOC represented good correlations with eubacterial numbers (r = 0.448, p<0.01). These results indicate that temperature, DOC and pH might be one of the main factors affecting variations of bacterial populations in the aquatic ecosystem. It was also suggested that FISH method is a useful tool for detection of slow growing nitrifying bacteria.

• Magazine of the Korean Society of Agricultural Engineers
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• v.11 no.1
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• pp.1598-1603
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• 1969

A field expeperiment has been conducted in order to explore possibilities of efficient and economical irrigation methods for the rice cultivation through which irrigation water may be saved and rice paddies may keep water for longer period of time, resulting in an increased yield of rice. Some of the major findings from the experimentation are summarized in the following. 1. There is slightly significant difference among experimental plots in the weight of rice straw. 2. The 9cm-lined plot proves to be the best in terms of the thickness. In this connection, however, it seems to by 3cm. 3. The wheat straw-lined plot is found superior in yield. However, this may be resulted in by the application of more fertilizer, and how long the plot could be durable may be problematic. Since every two or three years the straw-lining work has to be done, more labour may be required of the plot. 4. It would be inappropriate to expect any meaningful experimental results for the first year, since surface soil and deep soil are mixed up in the course of work. There is not observed any meaningful difference in the number of ears per stalk and in the number of grains per ear. However, in the lined plots, the number of tillers is slightly increased. 5. Irrigation has been applied by means of ordinary method after lining. When irrigation is applied at the interval of five to six days, irrigation water is saved by 44.9 per cent in the case of 9cm-lined plot, 39.7 per cent in the case of 6 cm-lined plot, and 36.3 percent in the case of 3 cm-lined plot. 6. An increased yields arenoted in the wheat straw-lined plot by 23.8 per cent, in the 9 cm-lined plot by 20.1 per cent, in the 3 cm-lined plot by 12 per cent. and in the case of vinyl-lined plot by 12.5 per cent. 7. The rate of maturity of grains is proved better, and the husking rate also found better(75%), that is, the quality of rice grains is improved.

• Journal of Animal Environmental Science
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• v.18 no.3
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• pp.191-200
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• 2012

This study was conducted to investigate the effects of application of cattle slurry on forage productivity and environmental pollution in rice paddy land. Cropping systems used in this study consisted of two designs, such as whole crop rice applied with standard fertilizer (MWRS) and whole crop rice applied with cattle slurry (MWRC). The field experiments were conducted on the clay loam at Backsanmyun, Kimje, Chunlabukdo province in Korea for three years (May 2006 to Apr. 2009). This study was arranged in completely randomized design with three replicates. The yield of dry matter of whole crop rice in MWRS was similar as compared with that of MWRC. The contents of crude protein of whole crop rice in MWRS significantly increased as compared with those of MWRC (P<0.05). However, the contents of acid detergent fiber (ADF), neutral detergent fiber (NDF) and total digestible nutrients (TDN) of whole crop rice were hardly influenced by cattle slurry application. The pH, and contents of T-N, $P_2O_5$ and organic matter (OM) in soil samples collected at the end of the experiment increased as compared with those at the beginning of the experiment. After the end of experiment, the concentrations of exchangeable cations (Ca, Na, Mg and K) in soil samples collected at the end of the experiment were remarkably higher than those at the beginning of the experiment (P<0.05). The concentrations of $NO_3$-N and $NH_4$-N in discharge water in MWRS, MWRC and DWBRC were higher in 2008 than those in 2007. But the concentration of $PO_4$-P in discharge water was hardly influenced by the cropping system during experimental period. The concentrations of $NO_3$-N, $NH_4$-N and $PO_4$-P in leaching water were hardly influenced by application of cattle slurry.

• Magazine of the Korean Society of Agricultural Engineers
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• v.13 no.1
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• pp.2191-2205
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• 1971

In this research, Nong-rim No. 6 was adopted as a test variety of rice. Rice seedlings were transplanted on June 14, 1970. Roots were settled into soil on June 20 and a total number of days irrigated of $21cm{\times}21cm$ and an area of $9.9m^2$ for a test plot were accepted, planting 70 stumps of rice in a test plot. The soil in test plots are classified by soil test as oam, and its chemical contents are as shown in Table 3. Irrigation water was secured by pumping from the Sudun stream that originates at the Suho reservoir. Accordingly, the qualities of irrigation. water are considered to be the same as those of water stored in the Suho reservoir. There were 54 days of intermittent rainfalls in total during the whole 110-day period of irrigation. As a result, it is likely that the growth of rice plants was influenced by rainfall at a comparatively great degree. In order to measure the amounts of water consumption, infiltrometers, measuring devices for the decreases of water depths and lycimeters were provided. As a result of measurements, an average daily rate of infiltration was observed to be 14mm/day. It is expected from this research that the effect of increased yield will be secured by supplying optimum amounts of water for irrigation on proper times, and that the amounts of water consumption for irrigation can be saved by applying suitable irrigation methods. The test results obtained are summarized as follows: 1. Yields produced in the test plots of continuous irrigation are lower than those in the test plots of rotational irrigation, i.e., yields produced at the test plots irrigatied once in a period of 8 days are higher by 27% in average than those produced at test plots of continuous irrigation. 2. The amounts of irrigation water for test plots, which have a clay layer of 9cm in thickness and vynil diaphragm without holes, are saved by about 52% in comparison with ordinary test plots. 3. Ears are sprouted 5 days earlier at continuous irrigation plots as compared with other test plots. 4. It seems that there are growing stages of rice plants such as those of forming and sprouting of ears, in which the amounts of irrigation water are consumed more in comparison with the other stages. Therefore, it may be possible to increase of decrease the amount of irrigation water, according to the growing stage of rice plant, so as to save irrigation water.

• Korean Journal of Ecology and Environment
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• v.37 no.4 s.109
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• pp.436-447
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• 2004

Wetland plants have evolved specialized adaptations to survive in the low-oxygen conditions associated with prolonged flooding. The development of internal gas space by means of aerenchyma is crucial for wetland plants to transport $O_2$ from the atmosphere into the roots and rhizome. The formation of tissue with high porosity depends on the species and environmental condition, which can control the depth of root penetration and the duration of root tolerance in the flooded sediments. The oxygen in the internal gas space of plants can be delivered from the atmosphere to the root and rhizome by both passive molecular diffusion and convective throughflow. The release of $O_2$ from the roots supplies oxygen demand for root respiration, microbial respiration, and chemical oxidation processes and stimulates aerobic decomposition of organic matter. Another essential mechanism of wetland plants is downward water movement across the root zone induced by water uptake. Natural and constructed wetlands sediments have low hydraulic conductivity due to the relatively fine particle sizes in the litter layer and, therefore, negligible water movement. Under such condition, the water uptake by wetland plants creates a water potential difference in the rhizosphere which acts as a driving force to draw water and dissolved solutes into the sediments. A large number of anatomical, morphological and physiological studies have been conducted to investigate the specialized adaptations of wetland plants that enable them to tolerate water saturated environment and to support their biochemical activities. Despite this, there is little knowledge regarding how the combined effects of wetland plants influence the biogeochemistry of wetland sediments. A further investigation of how the Presence of plants and their growth cycle affects the biogeochemistry of sediments will be of particular importance to understand the role of wetland in the ecological environment.

• Journal of Mushroom
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• v.7 no.4
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• pp.173-181
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• 2009

These studies were investigated for effect of concentration of sodium chloride on occurrence and growth of fruitbody in oyster mushroom, Pleurotus ostreatus. When the mycelia were inoculated and cultured on the PDA plate added with the different concentrations of sodium chloride, the growth of them were not affected at the concentration of 0.5%, started to decrease at 1.0% as compared with the PDA plate without sodium chloride, and they did not grow at 5.0%. When tested at the column filled with sawdust, the tendency was similar, but the decreasing rate of mycelial growth was gentle. In sawdust bottle cultivation sprinkled with the different concentration of sodium chloride solution at the different stage, the productivity and quality of fruitbody started to decrease at 3.0% of the solution and the yield at the treatment of 10.0% solution was only 47% of that in non-treated bottles. Treated at the different stages of mushroom development, treatment just after mushroom sprout did not show any different from that just after scraping spawn from the complete grown bottles. The sprinkle treatment at this stage looked better than that of the soaking with the solution before mushroom sprout. The yield at this treatment with 10% solution showed little damage with that of 90% of non-treated bottle. Sprinkle treatment during mushroom growth stage did not affect and showed almost same to non-treated bottle except the treatment with 10.0% solution. The treatment of this stage showed better results of growing characters than the treatment after and before mushroom sprouting even 10% solution. Morphological characteristics of oyster mushroom do not distinguish to treatment of different stage and concentration of sodium chloride solution. The analyzing data of quality on underwater usually used for oyster mushroom in Inchon, Yeongjong and Kanghwa area showed over-concentration to the standard for edible water and agricultural water. But it was not confirmed whether this water quality could affect to mushroom cultivation.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.1130-1136
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• 2011

This study was carried out to determine the effects of pig slurry on growth of potato (Solanum tuberosum L. cv. Dejima), soil chemistry properties and infiltration water quality in volcanic ash soil and non-volcanic ash soil of Jeju. Fertilization of liquid pig manure was based on nitrogen. In volcanic ash soil and non-volcanic ash soil, there was no difference in the height and diameter of stems in chemical fertilizer and liquid pig manure application treatments. Also yields of potatoes were no significantly difference in chemical fertilizer and liquid pig manure application treatments. pH in all soil was increased by application of liquid pig manure compared to the chemical fertilizer plot. Contents of exchangeable K in all soil were accumulated excessively by fertilization of pig manure 100% compared to the chemical fertilizer 100%. But there was no difference between the chemical fertilizer 50%+liquid pig manure 50% and chemical fertilizer 100%. No difference between the chemical fertilizer and liquid pig manure was observed in available phosphate, exchangeable Ca and Mg. $NO_3$-N concentration of infiltration water sample collected at 70cm of soil depth was lower non-fertilizer than chemical fertilizer and liquid pig manure application treatments. In volcanic ash soil, the $NO_3$-N concentration of infiltration water was decreased from early, except liquid manure 100%. In non volcanic ash soil, the $NO_3$-N concentration of infiltration water increased until October 8, but then was reduced. In all soils, $NO_3$-N concentration of infiltration water was higher in the liquid manure 100% than those in the chemical fertilizer 100% and chemical fertilizer 50%+liquid pig manure 50%, but there were no differences. In conclusion, the growth of potato, fertilization of soil and $NO_3$-N content of infiltration water were not different between chemical 50%+liquid pig manure 50% and chemical 100% plot. So, liquid pig manure could be substituted for some amount of chemical fertilizer.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.10 no.1
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• pp.1-18
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• 1974

Some coastal oceanographic investigations in Kwang Yang Bay were carried out bimonthly from April to September (The first half period of the research project) in 1974. The behaviour of the waters, distributions of water temperature and salinity and diffusion characteristic by dye release experiments in the bay are studied for the problems of practical importance in connection with water pollution. Velocities and directions of tidal currents at five fixed stations were observed. And dye diffusion experiment was also carried out on the sea. According to the results from this study, the salinity of the water is lower, ranging from about $28\;\textperthousand\;to\;32\textperthousand$, on all over the surface in the bay with the cause that the fresh water flows in from the Sumjin river. Diffusivities in this sea by means of Rhodamine B diffusion elliperiment were $785.6\;{\times}\;10^2\;\textrm{m}^2/sec$ in major axis, $15.6\;{\times}\;10^2 \;\textrm{m}^2/sec$/sec in minor axis in the direction on patch after 30 minutes from the dye release.

• Journal of Korean Society of Forest Science
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• v.96 no.1
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• pp.21-28
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• 2007

This study was conducted to investigate how the qualities of the stream water vary during the event in the regrowth and rehabilitation catchments in Yangju, Gyeonggido, from June to September 2005. During the observation periods, we sampled the stream water continuously by an auto-sampler (ISCO, 6712FR). The sampled waters were analyzed for suspended solid concentration, electrical conductivity and pH. The suspended solid concentration during the event increased concurrently with the stream flow. The peak of suspended solid concentration usually precedes the peak flow. The maximum value of suspended solid concentration was 420.89 mg/l in the event 1 at the regrowth catchment. Among the events simultaneously sampled at both catchments, the maximum values of suspended solid concentration were 212.8 mg/l and 58.24 mg/l in the event 3 at the regrowth and rehabilitation catchment respectively. The maximum value of EC in each event showed in the early stage of rising limb. EC decreased during the rising limb, and then showed minimum value at peak flow. EC gradually increased to pre-event value after minimum one. pH varied in similar pattern with EC. The maximum value of suspended solid concentration during each event was 2.8 to 4.3 times higher at the regrowth catchment than at the rehabilitation catchment. And the EC during each event was higher at the regrowth catchment than at the rehabilitation catchment. This results indicate that a disturbed forest soil during clear cutting at regrowth catchment still has been unstable.

• Journal of Korea Water Resources Association
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• v.57 no.5
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• pp.333-346
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• 2024

High-resolution medium-range streamflow prediction is crucial for sustainable water quality and aquatic ecosystem management. For reliable medium-range streamflow predictions, it is necessary to understand the characteristics of forcings and to effectively utilize weather forecast data with low spatio-temporal resolutions. In this study, we presented a comparative analysis of medium-range streamflow predictions using the distributed hydrological model, WRF-Hydro, and the numerical weather forecast Global Data Assimilation and Prediction System (GDAPS) in the Geumho River basin, Korea. Multiple forcings, ground observations (AWS&ASOS), numerical weather forecast (GDAPS), and Global Land Data Assimilation System (GLDAS), were ingested to investigate the performance of streamflow predictions with highresolution WRF-Hydro configuration. In terms of the mean areal accumulated rainfall, GDAPS was overestimated by 36% to 234%, and GLDAS reanalysis data were overestimated by 80% to 153% compared to AWS&ASOS. The performance of streamflow predictions using AWS&ASOS resulted in KGE and NSE values of 0.6 or higher at the Kangchang station. Meanwhile, GDAPS-based streamflow predictions showed high variability, with KGE values ranging from 0.871 to -0.131 depending on the rainfall events. Although the peak flow error of GDAPS was larger or similar to that of GLDAS, the peak flow timing error of GDAPS was smaller than that of GLDAS. The average timing errors of AWS&ASOS, GDAPS, and GLDAS were 3.7 hours, 8.4 hours, and 70.1 hours, respectively. Medium-range streamflow predictions using GDAPS and high-resolution WRF-Hydro may provide useful information for water resources management especially in terms of occurrence and timing of peak flow albeit high uncertainty in flood magnitude.