• Korean Journal of Soil Science and Fertilizer
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• v.46 no.5
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• pp.379-385
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• 2013

Although sorghum residue production was estimated to be $8{\sim}10Mg\;ha^{-1}$, most sorghum straw was used to be burnt or removed after harvest. This experiment was conducted to evaluate the effect of the incorporation of manured sorghum residues on soil physical properties from 2010 to 2012 in the converted paddy field. Five treatment with 3 replication consisted of control, inorganic fertilizer (NPK), manured residues, sorghum stover and sawdust manure. The incorporation level of organic source was $10Mg\;ha^{-1}$ without inorganic fertilizer NPK. The investigated physical parameters were bulk density (BD), porosity, water stability aggregate (WSA), water infiltration rater (WIR), penetration resistance (PR) and soil water retention characteristics (WRC) with soil depth. The incorporation of manured sorghum residues improved WIR significantly over inorganic fertilizer (NPK), sorghum residues and sawdust manure. The BD by incorporating with manured residues on sorghum was reduced significantly with crop residue over plot of NPK and sawdust. Significant increase in WSA was observed with stubble incorporation alone or manured sorghum residues. Soil WRC were significantly enhanced with manured sorghum residue incorporated without NPK. The average PR at 0~15 cm was 0.54 MPa for manured sorghum residues. For sawdust manure plot it was 0.42 MPa, for Sawdust manure plot 0.39 MPa and for NPK plot 0.54 MPa.

• Spatial Information Research
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• v.17 no.4
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• pp.431-443
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• 2009

Recently, turbidity problem is one of the hot issues in dam and reservoir management works. Main reason to bring about high density turbid water is sediment yield by rainfall intensity energy. Because existing researches didn't consider diverse types of crops, it was difficult to calculate more accurate soil erosion and sediment yield. This study was evaluated the reduction efficiency of soil erosion and sediment yield using ginseng layer extracted from IKONOS satellite image, and the area and the ratio of ginseng area represented $0.290km^2$ and 0.94%. The reduction efficiency of soil erosion considering ginseng area represented low value in 0.9% using GIS-based RUSLE model, because the area of ginseng was small compared to areas of other agricultural lands. To reflect future land use change, this study was calculated the reduction efficiency of soil erosion and sediment yield by considering many scenarios as kinds of crops of paddy, dry field, orchard, and other agricultural areas convert to the ginseng district. As result of analysis of them according to scenarios, scenario (1) in which dry field was converted to ginseng area and scenario (2) in which fully agricultural lands were converted to ginseng area showed high reduction efficiency as 31.3% and 34.8% respectively, compared to existing research which didn't consider ginseng area. Methodology suggested in this study will be very efficient tools to help reservoir management related to high density turbid water.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.254-261
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• 2014

BACKGROUND: This study was conducted to investigate effects of silicate fertilizer application on red pepper (Capsicum annuum L.) productivity with improving soil chemistry under plastic film house in paddy field. METHODS AND RESULTS: The silicate fertilizer was applied as 0, 100, 200, and 300 kg/10a as basal dressing before transplanting pepper plant seedlings. Cultivar of the pepper plant was Cheon-Ha-Dae-Se. Amounts of inorganic fertilizer applied as $N-P_2O_5-K_2O$=19.0-6.4-10.1kg/10a was estimated depending on soil test values. After applying 50% of nitrogen, 100% of phosphorus, and 60% of potassium fertilizers as basal dressing, the seedlings of pepper plant were transplanted. The rests of nitrogen and potassium fertilizers were applied as side-dressing after the first, second, and fourth harvests of red pepper. When comparing selected chemical properties of soils between before transplanting and after final(the fifth) harvest, soil pH, available $P_2O_5$, and exchangeable $Ca^{2+}$ increased with increasing the applications of silicate fertilizer, whereas electrical conductivity(EC) decreased. However, exchangeable $K^+$ was higher with the treatments of 100 and 200 kg/10a, and exchangeable $Mg^{2+}$ was higher with 300 kg/10a application. In addition, nitrogen and phosphorus concentrations of red pepper collected from the first harvesting stage decreased with increasing the applications of silicate fertilizer, but potassium, calcium, and magnesium concentrations in red pepper were highest with 300 kg/10a application. Yield of red pepper increased between 9.0 and 11.8% with the applications of silicate fertilizer. Marketable fruit rate of res pepper was highest(97.3%) with 200 kg/10a application. CONCLUSION: The application of silicate fertilizer as basal dressing in paddy-converted fields improved soil chemistry and increased red pepper productivity.

• Journal of Wetlands Research
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• v.24 no.4
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• pp.331-344
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• 2022

This study analyzed the characteristics of the soil and hydrological environment of abandoned paddy wetlands examined the changes in land cover type in the ecological affect area, analyzed the environmental factors of abandoned paddy wetlands, and examined the changes in land cover type in the ecological impact area. The ecological environment characteristics of the reference abandoned paddy wetlands were investigated through literature research, environmental spatial information service, and preliminary exploration of the abandoned paddy wetlands, and the basic data for the restoration of abandoned paddy wetlands ware provided by examining the changes in land cover type in the ecological impact area for 40 years. Through this study, it will be possible to manage the rapidly increasing number of abandoned farmland to be converted into wetlands so that it can perform functions equivalent to or greater than that of natural wetlands. In particular, as we checked the clues that abandoned paddy wetlands could spread to surrounding ecological influences through land cover changes, the study sites are highly likely to be reference wetlands, and if the topography, soil, water circulation system, and carbon reduction performance are analyzed carefully, it will be possible to standardize the development process. In addition, through the change in land cover, clues were confirmed that the abandoned paddy wetlands could spread to the surrounding ecological affect areas. The land cover type in the ecological impact area, forests was mainly distributed, but generally decreased rapidly in the last 10-20 years, and forests were changing from coniferous forests to broad-leaved forests, mixed forests, or grassland. It has not yet been fully called to the wetland, and it is found that it has maintained the form of barren or grassland, and as can be seen in the case of natural wetlands after more than 30 years after abandoned, it is expected that the transition will gradually proceed to wetlands that are structurally and functionally similar to natural wetlands.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.3
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• pp.367-372
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• 1997

Excessive water stress is one of major limiting factors affecting soybean yield, especially when soybean is grown in converted upland from paddy field. The present study was undertaken to know the genotypic variation in yield response of soybean to different environments in combination with soil texture and underground water table depth. Eight recommended soybean varieties in Korea and two supernodulating soybean mutants introduced from USA were planted in the lysimeter which was filled with two different soil types(sandy loam and clay loam). Of three underground water table depths(10, 30, and 50 cm) during whole growth stage, the lowest 10 cm was included to create excessive water stress. Yield was significantly different according to the underground water table depth and soybean genotypes, whereas soil type did not affect yield. There were significant interaction effects of soybean yield among soil type, soybean genotype, and underground water table depth. Yield of nts 1116 showed the highest across environments. Based on the regression analysis, the most stable variety was Sobaeknamulkong(bi=1.09). Jangsukong was fairly stable and high in yield, when compared to other soybean genotypes. However, nts 1116 was the most desirable ($D_i=228$) mainly due to the highest yield rather than the greater stability over environments. Multiple regression analysis revealed that shoot dry weight and nodule number were major factors affecting yield in the combined data over three water table depths and two soil types.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.1
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• pp.49-56
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• 1993

The net flux of global green house gases such as carbon dioxide($CO_2$), methane($CH_4$), and nitrous oxide($N_2O$) emitted from the rotation of paddy-upland soil during growing sesaon under different cropping system was determined. The results obtained were summarized as follows : 1. The net flux of $CO_2$ during the growing season was the highest from continuous cultivation of rice but the lowest from rotation cultivation of rice-soybean. Under the different cropping system the highst emission was from soil of continuous cultivation of rice, but the lowest from converted system. 2. The net emission of methane was the highest from the sold of continuous cultivation of rice, but the flux was remarkably decreased by differing the cropping system. 3. $N_2O$ was emitted greatly from the every two year rotation of potato-chinese cabbage and the next rank was from continuous cultivation of rice, but was decreased notably from rotation cultivation of rice-soybean and potato-chinese cabbage under rotation of paddy-upland cropping system. 4. The ratio of oxygen and carbon dioxide in the soil air was much different with glowing season, the ratio was varied with 4~10 percents for oxygen and 1~22 percents for carbon dioxide. The ratio of carbon dioxide was dozens or hundreds times to that of air, and the variation was very high also. 5. The emission of global green house gases such as carbon dioxide, methane and nitrous oxide was affected by the moisture, temperature and nutrients of soils and the growth period of crops.

• Journal of Korea Water Resources Association
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• v.30 no.5
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• pp.423-430
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• 1997

It is one of the most important factors to determine the effective rainfall for estimation of flood hydrograph in design schedule. SCS curve number (CN) method has been frequently used to estimate the effective rainfall of synthesized design flood hydrograph for hydraulic structures. But, it should be cautious to apply SCS-CN originally developed in U.S.A to watersheds in Korea, because characteristics of watersheds in Korea and cropping patterns especially like a paddy land cultivation are quite different from those in USA. New CN method has been introduced. Maximum storage capacity which was herein defined as Umax can be calibrated from the streamflow data and converted to new CN-I of direst condition of soil moisture in the given watershed. Effective rainfall for design flood hydrograph can be estimated by the curve number developed in the watersheds in Korea.

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.1
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• pp.1-9
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• 2017

Recently, it is increasing the grape farm which is converted from paddy field to orchard. These soil which are poor drainage extremely also can be damaged a lot by excessive water or flooding during heavy rain season on summer. Therefore the aim of this study was carried out to measure the changes of soil water potential and to compare the growth responses of 'Jinok' (Vitis spp.) and 'Campbell Early' (V. labruscana) grapes under three drainage systems (control, conventional drainage, and under drainage). After heavy rain, soil water potential holding times above -15 kpa applied water excessive were 352, 348 and 180 hours in control, conventional, and under drainage systems, respectively. The clay content of the under drainage system was lower than the other systems about 8-12%. The crop water stress index was lowest in the under drainage and highest in the control. Also, photosynthetic rate has showed the opposite result with crop water stress index. It was significant differences between the treatments but, the value has not shown significantly different between the varieties. In addition, leaf area and the trunk growth rate was more effective in under drainage than in the control and conventional drainage.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.5
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• pp.374-380
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• 2014

To estimate greenhouse gas (GHG) emission, the inventory of rice cultivation at the farming without agricultural chemicals was established from farmers in Gunsan, Jeonbuk province in 2011~2012. The objectives of this study were to calculate carbon footprint and analyse the major factor of GHGs. To do this, we carried out a sensitivity analysis using the analyzed main factors of GHGs and estimated the mitigation potential of GHGs. Also we suggested agricultural methods to reduce GHGs that can be appled by farmers at this region. At the farming system without agricultural chemicals, carbon footprint of rice production unit of 1 kg was 2.15 kg $CO_2.-eq.kg^{-1}$. Although the amount of carbon dioxide ($CO_2$) emission was the largest among GHGs, methane ($CH_4$) emission had the highest contribution to carbon footprint on rice production system when it was converted to carbon dioxide equivalent ($CO_2-eq.$) multiplied by the global warming potential (GWP). Main source of $CO_2$ emission in the rice farming system without agricultural chemicals was combustion of fossil fuels used by agricultural machinery. Most of the $CH_4$ was emitted during rice cultivation practice and its major emission factor was flooded paddy field in anaerobic condition. Also, most of the $N_2O$ was emitted from rice cultivation process. Major sources of the $N_2O$ emission was application of fertilizer such as compound fertilizer. As a result of sensitivity analysis in energy consumption, diesel had the highest sensitivity among the energy inputs. With the reduction of diesel consumption by 10%, it was estimated that $CO_2$ potential reduction was about 2.0%. With reducing application rate of compound fertilizer by 10%, the potential reduction was calculated that $CO_2$ and $N_2O$ could be reduced by 0.5% and 0.9%, respectively. At the condition of 10% reduction of silicate and compost, $CO_2$ and $CH_4$ could be reduced by 1.5% and 1.6%, respectively. With 8 days more drainage than the ordinary practice, $CH_4$ emission could be reduced by about 4.5%. Drainage and diesel consumption were the main sources having the largest effect on the GHG reduction at the farming system without agricultural chemicals. Based on the above results, we suggest that no-tillage and midsummer drainage could be a method to decrease GHG emissions from rice production system.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.6
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• pp.502-509
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• 2013

To estimate greenhouse gas (GHG) emission, we established inventory of conventional rice cultivation from farmers in Gunsan and Iksan, Jeonbuk province in 2011~2012. This study was to calculate carbon footprint and to analyse the major factor of GHGs. We carried out a sensitivity analysis using the analyzed main factors of GHGs and estimated the mitigation potential of GHGs. Also we tried to suggest agricultural methods to reduce GHGs that farmers of this case study can apply. Carbon footprint of rice production unit of 1 kg was 2.21 kg $CO_2.-eq.kg^{-1}$. Although amount of $CO_2$ emissions is largest among GHGs, methane had the highest contribution of carbon footprint on rice production system after methane was converted to carbon dioxide equivalent ($CO_2$-eq.) multiplied by the global warming potential (GWP). Source of $CO_2$ in the cultivation of rice farming is incomplete combustion of fossil fuels used by agricultural machinery. Most of the $CH_4$ emitted during rice cultivation and major factor of $CH_4$ emission is flooded paddy field in anaerobic condition. Most of the $N_2O$ emitted from rice cultivation process and major sources of $N_2O$ emission is application of fertilizer such as compound fertilizer, urea, orgainc fertilizer, etc. As a result of sensitivity analysis due to the variation in energy consumption, diesel had the highest sensitivity among the energies inputs. If diesel consumption is reduced by 10%, it could be estimated that $CO_2$ potential reduction is about 2.5%. When application rate of compound fertilizer reduces by 10%, the potential reduction is calculated to be approximately 1% for $CO_2$ and approximately 1.8% for $N_2O$. When drainage duration is decreased until 10 days, methane emissions is reduced by approximately 4.5%. That is to say drainage days, tillage, and reducing diesel consumption were the main sources having the largest effect of GHG reduction due to changing amount of inputs. Accordingly, proposed methods to decrease GHG emissions were no-tillage, midsummer drainage, etc.