• Korean Journal of Agricultural Science
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• v.39 no.4
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• pp.545-553
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• 2012

In Asia, including Japan and Korea, rice paddies occupy the largest cultivated area in agricultural land. Rice paddies provide the habitats for many organisms including endemic species, sustaining high biodiversity. Insect natural enemies inhabiting rice paddies have an important function for rice production as agents of 'ecosystem services' because they play a major role in suppressing rice pests. The diversity and abundance of natural enemies can be a good index reflecting the 'healthiness' of agro-ecosystem services in rice paddies. The present study investigates whether insect natural enemies could be good biological indicators for general arthropod biodiversity and agricultural practice. First, the concept of ideal bio-indicators was summarized. The strategy to explore and select such bio-indicators was then proposed. Lastly, field survey was made to evaluate the abundance and biodiversity of natural enemies in Japanese rice paddies where chemical inputs, i.e., insecticide use, were different. The results showed that reduction of chemical inputs led to an increase in species richness or diversity of natural enemies including parasitoids and predators. Then, the data were analyzed to examine suitable indicator species to assess environmental soundness of agricultural practice and biodiversity in rice paddies. The density of several species of natural enemies did respond both to pesticide use and to general arthropod biodiversity. The analyses thus have indicated that natural enemies can be suitable as bio-indicators. Usefulness of indicator species in rice paddies is discussed in the context of ecologically sound agriculture.

• Journal of Fisheries and Marine Sciences Education
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• v.29 no.1
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• pp.51-63
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• 2017

Rice Fields have provided large areas of open water for centuries in regions with a variety of rice-growing cultures, and, in addition to producing rice also provide other animal and/or plant food sources and medicinal plants, thus acting as wetland systems and helping to sustain livelihoods and human well-being in these regions. Also rice fields in many parts of the world support important wetland biodiversity, such as reptiles, amphibians, fish, crustacean, insects and mollusca, and play a significant ole in water-bird flyways and the conservation of water-bird populations. The purpose of this study is to find a way conservation of rice fields in connection with paddies's laws, for example, amend the Conservation of Wetlands Law or legislate for the conservation of paddies.

• Asian Journal of Atmospheric Environment
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• v.7 no.2
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• pp.85-94
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• 2013

Methane concentrations have been monitored at the Anmyeon-do Observatory, Korea, since 1999. In recent years, the methane concentration has increased, but the sources of this increase have yet to be identified. This study was designed to identify the major source contributing to the increase by using World Data Centre for Greenhouse Gases (WDCGG) data and the Greenhouse Gases Emission Presumption (GEP) method. The data were collected at Anmyeon-do between 2003 and 2009 (except 2008), and the analyses showed that the increase in methane concentration originated mainly in rice paddies around the observation point. The annual average methane concentration at Anmyeon-do was 1894 ppb, of which 100-103 ppb (5.3-5.4%) was shown to originate mainly from rice paddies. The seasonal fluctuation in methane concentration from May to October estimated by the GEP method was compared with experimental data of previous research conducted on rice paddies. The close match obtained through this comparison shows that the GEP method is effective. The difference in methane concentration was also analyzed in terms of land use and land cover. It was shown that although rice paddies account for only 14.7% of the area surveyed, they accounted for between 69 and 90% of the total increase in methane concentration. These results confirm that rice paddies are the main source of the increase in methane concentration observed at Anmyeon-do.

• Korean Journal of Agricultural Science
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• v.2 no.1
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• pp.151-177
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• 1975

To obtain the informations on the checking factors of the effecient utilization of paddies in chungnam province and study on the effecient working system and high productive cropping system in paddies, the utilization state of paddies including environmental conditions were investigated at sample 1,500 farms. The results obtained are summarized as follows; 1. The difficulty of drainage in paddies was the most important factor checking the utility of paddies. Delayed transplanting of rice and lack of labour were also important checking factors on the efficient utilization of paddies. 2. The utilization of paddies was rather effecient at small size farms of which farmers were almost poor, and most of them cultivated barley for their own food. 3. Considering climatic conditions, pre-crops of rice must be harvested before June 10 tho and the marginal transplanting date of rice plant is June 25 th. 4. In case of planting barley as a post-crop after rice, the spread seeding by rotary before plowing was most efficient with lowest cost. 5. Considering rice cultivation, yield of barley and net income, the most efficient cropping system was "Josaengtongil + Olbori".

• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.6
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• pp.56-62
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• 2000

The NRCS curve number (CN) method has been widely adopted in practice to synthesize runoff hydrographs from small watersheds with complex land use. It may not be valid to apply this model for irrigated paddies, since hydrological characteristics of irrigated rice paddies are not sufficiently considered in CN method. This paper attempts to extend the capability of the well-known SCS TR-20 model to local conditions by formulating a submodel for the runoff-processes in paddies. The modified model was tested with field data from the Baran watershed. The results were in good agreement with field data. It was also applicable to simulate runoff changes resulting from land use changes within the watershed.

• Journal of Wetlands Research
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• v.4 no.1
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• pp.33-41
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• 2002

Investigated was the ground-walking Coleoptera at the moor and adjacent forest at 800 m and rice paddies at lower level of 50 m in altitude. There were 5 species belonging to 5 genera and 2 families, 4 species belonging to 4 genera and 3 families, and 17 species belonging to 11 genera and 2 families respectively. Diplous depressus (Gebler) was the dominant species at the moor and forest in distinctive numbers, while Pheropsophus javanus (Dejean) was the one at the paddies. Three investigated sites supported independently their ground-walking Coleoptera groups. The moor group seemed to fail in establishing the resident Coleoptera community. The fact may imply to be related a kind of the pioneer species in early dry succession that D. depressus was found in a considerable range between forest and moor. The Coleoptera groups of moor and forest was different from that of paddies in species structure.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.819-835
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• 2009

In order to investigate the field application of selected stabilization methods(cover soil method, surface and total interval treatment of embankment method) on rice paddies contaminated by heavy metals, column test was carried out with heavy metal-contaminated soils collected from rice paddies around abandoned mine site. Columns were made by acrylic and filled with untreated soil, treated soil mixed with amendments(lime stone and steel refining slag) and uncontaminated cover soil according to the design report. Distilled water was discharged into the columns with the velocity of 1 pore volume/day. During test, pH, EC, and heavy metal concentration were measured in the regular term. The column test result showed that the selected stabilization methods were effective remediation method to stabilize heavy metals in paddy soils, but it was also expected that application of surface treatment methods was required the careful observation on pH variation due to the lowest increment.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.3
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• pp.65-72
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• 2002

Rainfall and runoff data from a forested watershed and irrigated rice paddies at the Bal-an experimental watershed were monitored and analyzed to investigate the variations of runoff characteristics with different land use. The comparisons were conducted fourteen storm events ranging 21.8∼190.2 mm of rainfall. Field data showed that direct runoff from paddies and forested watershed are not significantly different in volume. The peak discharge from forest watershed was less than that from paddies far lighter storms, but became greater fur heavier storms. The peak runoff from the forest watershed was 39 percent greater than from the paddies. The results demonstrate that paddies play an important role to reduce peak discharge from heavy storms as compared to forest.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.525-530
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• 1999

A modified SCS TR-20 model that may be applied to a watershed having rice paddies as a land use type, was formulated and applied to a gauaged watershed. The model was applied to the Balan watershed of 26$\textrm{km}^2$ in size for estimation strorm hydrographs . And the simulation results from the model were also compared with thoses from the SCS model. The results showed that paddy fields play an important role to reduce peak runoff. When fractions of paddies are left to fallow conditions or when rice crop is replaced by other, the peak runoff was found to increase up to 10 to 20 percentg . The reduction rates in peak runoff appear to become greater for heavier storms or higher antecedent moisture conditions.

• Korean journal of applied entomology
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• v.42 no.4
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• pp.361-365
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• 2003

Several species of planthoppers such as brown planthopper, N. lugens (Stal) (BPH), smaller brown planthopper, Laodelphax striatellus (Fall n) (SBPH), and white-backed planthopper, Sogatella furcifera (Horv th) (WBPH) are distributed in Korean rice paddies but not easy to discriminate them in situ. Accurate discrimination of them is an indispensable process in the forecasting for their outbreak and control. Especially, innovative discrimination method for BPH was required because BPH was one of the most important insect pest of rice. Nymphs and adults of BPHs, SBPHS, and WBPHS, thus, were examined their morphological characteristics in the paddies and laboratory. The nymphs of BPH had different characters from those of SBPH and WBPH. The nymphs of BPH had white fluorescent spot between bottom of compound eye and antenna, while there was no that spot the other two species. The white spot was the brightest at the nymphs just after hatching and getting weaker as the nymph developed. At last the white spot was totally disappeared at the adult stage. This white spot was innovative criterium to discriminate nymphs of BPH, SBPH, and WBPH in rice paddies.