• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.4
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• pp.1-8
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• 2014

Appropriate amount of water supply to paddy fields in proper time is important to achieve efficient agricultural water management. The purpose of this study is to evaluate the irrigation water supply adequacy for paddy fields using water level data in irrigation canals. For the evaluation, the real-time water level data were collected from main canals in the Dongjin irrigation district for 2 years. Using the water level data, delivered irrigation water amounts at the distribution points of each canal were calculated. The water balance model for paddy field was designed considering intermittent irrigation and the irrigation water requirement was estimated. Irrigation water supply adequacy was analyzed from main canals to the irrigation blocks based on the comparison between estimated requirement and delivered irrigation water amounts. From the adequacy analysis, irrigation water supply showed poor management condition in 2012 with low efficiency except the Daepyong canal section, and the adequacy in 2013 was good or fair except the Yongsung canal section. When irrigation water for paddy fields was insufficient, water supply adequacy was affected by irrigation area, but when irrigation water was enough to supply, adequacy was affected by distance from main canal to distribution points. These results of the spatial and temporal dimensions of the irrigation adequacy could be utilized for efficient irrigation water management to improve the temporal uniformity and equity in the water distribution for paddy fields.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.2
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• pp.134-142
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• 2017

Crop production in rice paddy fields is of great importance because of declining rice consumption and the low self-sufficiency ratio for field crops in Korea. A controlled drainage system (CDS) is recognized as an effective means to adjust water table (WT) levels as needed and control soil water content to improve the soil environment for optimum crop growth. The present study evaluated the effects of a CDS on soil characteristics, including soil water distribution and soybean development in paddy fields. The CDS was installed with two drain spacing (3 m and 6 m) at the experimental paddy field at the National Institute of Crop Science, Miryang, Korea. It was managed with two WT levels (0.3 m and 0.6 m) during the growing season. Soil water content, electrical conductivity and plant available nitrogen content in the soil were significantly greater in the 0.3 m WT management plots than in the 0.6 m plot and the control. At the vegetative stage, chlorophyll content was significantly lower with higher WT control because of excess soil moisture, but it recovered after the flowering stage. Soybean yield increased with WT management and the 0.6 m WT treatment produced the greatest grain yield, $3.38ton\;ha^{-1}$, which was 50% greater than that of the control. The CDS directly influenced outflow through the drains, which significantly delayed nutrient loss. The results of this study indicated that WT management by CDS can influence soil characteristics and it is an important practice for high yielding soybean production in paddy fields, which should be considered the crop growth stages for stable crop production.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.1
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• pp.52-66
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• 2009

The increase of rice productivity, the decrease of rice demand, aging farmers, and the market-opening of rice along with the domestic and international conditions changes have been led to the increase of the abandoned rice paddy fields. Such abandoned rice paddy fields have been left in many areas and most of them have become wetlands. The purpose of this study is methodology of selection to the wetland for development in the abandoned rice paddy fields along with surroundings. The selection of habitat suitability index assessment study to conservation and restoration was done through hydrology, wild animals habitation, wetland vegetation, outside disturbance, and natural purification capacity assessment. In addition, the same method was applied to assessment items and standards for both the restoration site selection and the type of restoration. Both assessment items and standards were applied to the sites, drawn on the maps, and overlayer for the comprehensive map, and then the wetland suitability index was applied to the suitable site. The development technique was applied to 10 sites near the Banwol Stream watershed in Gunpo, Gyeonggi province. The selection of conservation, restoration, and the optimal sites can lead to not only the biodiveristy increase in agricultural or semi natural areas but also to the establishment of ecological networks in national level.

• Korean Journal of Environmental Agriculture
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• v.40 no.3
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• pp.169-178
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• 2021

BACKGROUND: The Ministry of Agriculture, Food and Rural Affairs is promoting agri-environment conservation program to induce farmers to participate in agricultural environment improvement and conservation activities. However, assessment tools based on scientific evidence are needed to determine the effectiveness of the program objectively and quantitatively. Therefore, this study was performed to develop plant indicators in order to efficiently evaluate the effects of the agri-environment conservation program promoted by the Ministry of Agriculture, Food and Rural Affairs. METHODS AND RESULTS: The survey was conducted in five regions (Hampyeong, Boryeong, Mungyeong, Hongseong, and Sangju) participating in the agri-eonvironment conservation program. In each region, twenty paddy fields were investigated (ten paddy fields included in the program and ten paddy fields not included in the program). A total of 231 taxa vascular plants were identified in the paddy fields that were included in the agri-environment conservation program, and a total of 177 taxa were identified in the paddy fields that were not included. The average species number occurred on each field was 55.8 taxa in the fields included in the program, and 35.0 taxa in the fields not included in the program. The difference in occurring plants between two groups was found to be more higher in perennial plants than in annual plants. We selected the six groups as indicator plants through five criteria such as perennial plants and broadly occurring species, etc. to verify the effectiveness of the agri-environment conservation program: Taraxacum spp., Ixeris spp., Viola spp., Platago spp., Calystegia spp., and rare and endagered species. There was a high positive correlation between the score calculated using these indicator plants and the total number of plants species. CONCLUSION: This study suggests that it is possible to evaluate the agro-ecological environment by using indicator plants. The selected indicator plants can be effectively used to verify the effectiveness of projects such as agri-environmental conservation programs in the future.

• Journal of the Korean Institute of Landscape Architecture
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• v.37 no.1
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• pp.18-27
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• 2009

The purpose of this study is to understand the scale of temperature change following large-scale urban developments in paddy fields to present possible measures to preserve suburban area paddy fields and to lower the scale of temperature increase after developing paddy fields in urban areas. The study was conducted in Bupyeong and Bucheon of Incheon Metropolitan City. The satellite image($1989{\sim}2000$) before and after the development of old paddy fields were used to analyze the land surface temperature changes according to the land use types. Building coverage, green coverage, non-permeable pavement coverage, and floor area ratio(FAR) were selected as the factors that influence urban temperature changes and the temperature estimation model was constructed by using correlation and regression analyses. The before and after satellite images of Bupyeong and Bucheon were classified into forests, greens and plantations, paddy fields, unused lands, and urban areas. The results indicate that most of the paddy fields that existed in the center of Bupyeong and Bucheon were converted into unused lands which were undergoing construction to become new urban areas. The difference between the surface temperatures of May 17th, 1989 and May 7th, 2000 was analyzed to reveal that most land converted from paddy fields to unused lands or urban areas saw an increase in surface temperature. Han River was used as a comparison to analyze the average surface temperature changes($1989{\sim}2000$) in former paddy fields. The scale of temperature changes were: $+1.6697^{\circ}C$ in urban parks; $+2.5503^{\circ}C$ in residential zones; $+2.9479^{\circ}C$ on public lands, $+3.0385^{\circ}C$ in commercial zones, and $+3.1803^{\circ}C$ in educational zones. The correlation between building coverage, green coverage, non-permeable pavement coverage, or floor area ratio(FAR) and surface temperature increases was also analyzed. The green coverage to temperature increases, but building coverage, non-permeable pavement coverage, and floor area ratio(FAR) had no statistically significant temperature increases. The factors that influence urban temperature changes were set up as independent variables and the surface temperature changes as dependent variables to construct a surface temperature change model for the land use types of former paddy fields. As a result of regression analysis, green coverage was selected as the most significant independent variable. According to regression analysis, if farmland is converted into an urban area, a temperature increase of $+3.889^{\circ}C$ is anticipated with 0% green coverage. The temperature saw a decrease of $-0.43^{\circ}C$ with every 10% increase of green coverage.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.4
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• pp.75-85
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• 2005

A study was performed to examine the effects of reclaimed-water irrigation on microorganism con-centration in ponded-water of paddy rice plots. Several treatments were used and each one was triplicated to evaluate the change of indicator microorganisms (total coliforms (TC), fecal coliforms FC), and E. coli) concentrations in 2003 and 2004 growing seasons. Their concentrations increased significantly right after irrigation, but decreased about $45\%$ in 24 hours. It implies that agricultural activities such as plowing and fertilizing should be practiced one or two days after irrigation considering health-risks. Treatments with UV-disinfected water irrigation demonstrated significantly lower concentrations than others including control plots where natural surface water was irrigated. The monitoring results from actual paddy rice fields and experimental paddy plots showed that concentrations of indicator microorganisms ranged from $10^2\;to\;10^5$ MPN/100mL. A comprehensive assessment of existing agricultural practices and a thorough monitoring in the field as well as treatment-plots are recommended to make more realistic national guidelines more applicable. UV-disinfected water irrigation reduced microorganism concentrations in paddy fields down to below the concentration of conventional paddy rice culture, and is thought to be an effective and feasible measure fur agricultural reuse of secondary effluent.

• The Korean Journal of Pesticide Science
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• v.12 no.1
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• pp.74-81
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• 2008

To elucidate the exposure of pesticide in agricultural environment and to investigate distribution of pesticide in paddy fields. This experiment was carried out to clarify pesticide distribution in paddy fields applied with different formulations and growing stages. Initial dissipation rate of applied butachlor EW and oxadiazon EC before rice planting were more than 90% within 3 days in paddy fields. The distribution of a.i. in the pesticide formulations tested depended upon the elapsed time at each growing stage of rice plant after application. Most of pesticides applied within 15 days after transplanting of rice seedlings, more than 95%, were located in the surface water and soil regardless of pesticides; butachlor, thiobencarb and molinate GR. The distribution of iprobenfos GR, tricyclazole WP and phenthoate EC, after application 2 hours in middle growing stage (46 days after rice planting) were shown as 16.1, 48.9 and 38.9% in surface water, 83.6, 15.4 and 10.7% in soil, and 0.3, 35.7 and 50.4% in rice plants of paddy fields, respectively. Also tricyclazole WP and phenthoate EC, after application 2 hours in the late rice growing stage (90 days after rice planting) were distributed to 7.8 and 9.8% in surface water, and 21.7 and 5.1% in soil, and 70.5 and 85.1% in rice plants of paddy fields, respectively.

• Korean Journal of Environmental Biology
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• v.40 no.2
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• pp.138-147
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• 2022

Paddy fields are important habitats for maintaining the biodiversity of agricultural ecosystems. Recently, as the need for safe food and biodiversity conservation has increased, the rice cultivation methods have undergone changes. This study was conducted to investigate the fish fauna in Environmentally Friendly Paddy fields (EFP) and Conventional Paddy fields (CP), and compare the characteristics of Misgurnus anguillicaudatus and Aphyocypris chinensis populations in EFP and CP. A total of 2,703 fish were collected and classified into six families and 13 species. Our results showed that there was a difference in the proportion of fish populations in the two paddy fields, and the number of individuals in EFP was higher than in CP. The weight values of M. anguillicaudatus were higher in EFP than in CP, and the total length, body length, and weight values of A. chinensis were higher in EFP than in CP. Conditional factor(K) values also showed similar trends in EFP and CP. Our results indicate that the farming practices in paddy fields have a significant effect on the characteristics of M. anguillicaudatus and A. chinensis populations, and the results of this study can be used as basic data for securing biodiversity in future agricultural ecosystems.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.4
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• pp.336-342
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• 1993

To obtain the basic information necessary for the development of soybean varieties well adaptable to upland-paddy field rotational croppings, the difference of growth characteristics between upland and paddy-field including yield potentials of current recommending soybean varieties were evaluated. The growth characteristics, both above and under-ground, which were measured at flowering stage were generally greater in paddy-field but the number of root nodules was much greater in upland, thus the artificial inoculation was practically recommended for soybean growing in paddy-fields. Mean seed yield was generally higher in paddy-fields than in upland. All soybean varieties showed higher seed yield in the early planting date, April 20, were somewhat susceptible to soybean mosaic virus(SMV), thus they could be escaped from the disasterous endemic necrotic soybean mosaic virus(SMV-N). Soybean varieties showed over 4.0 tons/ha seed yield in the paddy-field were Williams 79, Union, SS77053, and Namhaekong. At the same time, Jangyeobkong and Danyeobkong were the most stable soybean varieties among the tested soybean varieties with less than 10% of coefficient variation values in all planting dates in paddy fields. Compared with Hwangkeumkong which is most widely being cultivated on farmer's fields, soybean varieties showed high yields in paddy-field were higher in plant height, less in the number of branches, and more in the number of nodes on main stem. At the same time, they had medium seed size which would bring the good germination and stands. Disease resistance especially for necrotic soybean mosaic virus was also one of the most decisive factors in seed yields for the early planted soybeans.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.2
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• pp.132-139
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• 2010

To manage the effluent nutrients amounts from rice paddy fields using free range ducks or rice bran, we evaluated the effects of a purifying paddy field which is no fertilizer, no pesticides, and dense rice seedling having a concept of constructed wetland. The experimental paddy field was located at downstream in the watershed of ducks using rice culture area in Milyang. The purifying paddy of land design were treated with seeding method, and vegetation type. As land design, direct seeding on plane, and direct seeding on high-ridge field in 2007. Planting rice only, and planting rice with water hyacinth were treated as vegetation type in purifying paddy in 2008. The purifying paddy fields were effective to reduce amount of T-N and T-P contents in effluent to 33.2~45.3%, and 53.1~55.4%, respectively. The direct seeding on high-ridge treatment, having long residence time of effluent water was more effective than plane plot as T-N 0.29 $g^{-1}m^{-2}d^{-1}$, and T-P 0.031 $g^{-1}m^{-2}d^{-1}$. The planting rice with water hyacinth treatment was effective than planting rice only as T-N 0.23 $g^{-1}m^{-2}d^{-1}$, and T-P 0.049 $g^{-1}m^{-2}d^{-1}$. The optimum area of purifying paddy field to treats all effluent were found out 3.2~4.7% of rice culture area using free range ducks, and rice bran at upper stream.