• The Korean Journal of Ecology
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• v.21 no.3
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• pp.203-215
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• 1998

The weed vegetion of the rice fields in south Korea was researched in terms of syntaxonomy and synecology. Total 186 releves were analyzed by the Zurich-Montpellier school's method. 10 syntaxa were recognized: Stellario-Alopecuretum amurensis ass. nov. hoc loco, Alopecuro-Ranunculetum scelerati Miyawaki et Okuda 1972, Hemistepto-Capsellietum bursa-pastoriae ass. nov. hoc loco, Oryza sativa-Echinochloa crusgalli community, Sagittario-Monochorietum plantaginea Miyawaki 1960, Cyperus iria community, Hyperico-Juncetum decipiens ass. nov. hoc. loco, Spirodela-Lemna paucicostata community, Lemno-Salvinetum natans Miyawaki et J. Tuxen 1960. The Oryzo-Echinochloion oryzoides Bolos et Masclans 1955 and the Alopecurion amurensis Miyawaki et Okuda 1972 are representative of the summer annual plant community and the winter annual plant community. It was emphasized that syntaxonomical and synecological study on the ruderal and segetal weed vegetation in Korea should be accomplished in consideration of bioclimatic condition of summer monsoon climate of Korean Peninsula.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.3 no.4
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• pp.199-203
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• 2022

The spring home range and habitat use of the spot-billed duck in Korea were studied using GPS-mobile phone-based telemetry (WT-300). The study areas were Anseong-si, Seosan-si, Nonsan-si, and Sejong-si. Analysis was performed using minimum convex polygon (MCP) and kernel density estimation (KDE) spot-billed ducks had an average home range of 70.28 km² (standard deviation [SD]=84.50, n=6), and a core habitat (50%) 2.66 km² (SD=2.60, n=6), according to MCP and KDE, respectively. Wetlands (41.5%) and rice fields (35.7%) were highly used as habitats. The rice field use rate was high during the day, and the wetland utilization rate was high at night. Rice fields and wetlands were the primary habitats in spring.

• Journal of The Korean Society of Grassland and Forage Science
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• v.40 no.3
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• pp.149-155
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• 2020

Cattle feeding in South Korea has been heavily dependent on domestically produced rice straw and imported grain. Around 42% of domestically produced rice straw is utilized for forage, and the remainder is recycled to restore soil fertility. Approximately 35% of round baleages were made with rice straw. However, higher quality hay is desired over rice straw. Due to increasing stockpiles of rice, there has been an economic burden on the government to store the surplus; therefore production of annual forage crops in rice fields has been further promoted in recent years. Hay import from the USA currently constitutes more than 80% of total imported hays. The main imported hays are alfalfa (Medicago sativa), timothy (Phleum pretense), and tall fescue (Festica arundinacea). The estimated forage required for cattle feeding was approximately 5.4 million MT in 2016. Domestically produced forage sates only 43% of that value, while low quality rice straw and imported hay covered the rest of demand by 33% and 20%, respectively. As utilization of domestically produced forage is more desirable for forage-based cattle production, long-term strategies have been necessary to promote domestic production of high quality baleage. One such strategy has been utilizing the fertile soil and abundance of fallow rice fields of western region of S. Korea to produce forage crops. Italian ryegrass (Lolium multiflorum) is the most successfully produced winter annual in the region and is approximately 56% of the total winter annual forage production. Forage sorghums (Sorghum bicolor), sorghum × sudangrass hybrids, and hybrid corn (Zea mays) produce a substantial amount of warm-season forage during summer. Produced forage has been largely stored through baleage due to heavy dew and frequent rains and has been evaluated according to S. Korea's newly implemented baleage commodity evaluation system. The system weighs 50% of its total grading points on moisture content because of its importance in deliverable DM content and desirable baleage fermentation; this has proved to be an effective method. Although further improvement is required for the future of forage production in South Korea, the current government-led forage production in rice fields has been able to alleviate some of the country's shortage for quality hay.

• Korean Journal of Ecology and Environment
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• v.52 no.4
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• pp.366-377
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• 2019

Paddy wetlands are a critical habitat for a variety of wild animals, and their rapid development and environmental changes pose a threat to the conservation of agrobiodiversity. The objectives of this study were to evaluate the habitat characteristics of anuran inhabiting paddy wetlands and identify major environmental variables affecting their distributions. The study was conducted in the Daeho reclaimed area in Dangjin, from March to October 2018. In this study, we found three anuran species (Pelophylax nigromaculatus, Hyla japonica and Pelophylax chosenicus). The environmental factors affecting the three species were identified as air temperature, humidity, water-depth, and micro-habitats. H. japonica were affected by water temperature, and P. chosenicus were affected by rice height and types of farming practices. All the three species richness was correlated with air temperature, humidity, and water-depth positively, and the three species used rice transplanted paddy fields the most. It was also found that paddy is the most preferred of the micro-habitats during the breeding season, so the survey area is considered to be used as the major breeding sites for the three species. P. chosenicus were more observed on environmental-friendly paddy fields than conventional paddy fields, which appears to be differences in their surroundings environment caused by predators and weeding. It will be needed to identify their relationship with predators, their preferred food resources and the richness and diversity of wild vegetation around paddy wetlands.

• Journal of Ecology and Environment
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• v.35 no.2
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• pp.149-155
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• 2012

Rice paddy fields have been recognized as an alternative habitat for avian wetland foragers, and fish-rice farms have become a new tool in improving the abundance of aquatic animals. However, the use of the habitats by avian foragers, particularly by oriental storks ($Ciconia$ $boyciana$), was not well understood. In the present study, we investigated how a fish-rice farm influenced the abundance of aquatic animals and documented the foraging behavior of the two captive bred oriental storks in a closed semi-natural paddy field. Our results showed that the fish refuge pond (water depth 40 cm) had a higher abundance of fish whereas the areas planted with rice (water depth 20 cm) had more tadpoles and some aquatic insects. The two captive bred oriental storks captured mostly fish and aquatic insects in the rice-planted area and mostly fish in the fish refuge pond. The two oriental storks had higher foraging success and spent more time for foraging in the rice-planted area than in the fish refuge pond. This result suggests that the oriental storks might prefer foraging in the area with fish, aquatic insects, and amphibians under a greater success rate presumably due to shallow water depth in the paddy fields with a fish-rice farm.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.917-919
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• 2003

This paper demonstrates that RADARSAT ScanSAR data can be an important data source of radar remote sensing for monitoring crop systems and estimation of rice yield for large areas in tropic and sub-tropical regions. Experiments were carried out to show the effectiveness of RADARSAT ScanSAR data for rice yield estimation in whole province of Guangdong, South China. A methodology was developed to deal with a series of issues in extracting rice information from the ScanSAR data, such as topographic influences, levels of agro-management, irregular distribution of paddy fields and different rice cropping systems. A model was provided for rice yield estimation based on the relationship between the backscatter coefficient of multi-temporal SAR data and the biomass of rice.

• Korean Journal of Organic Agriculture
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• v.19 no.spc
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• pp.135-138
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• 2011

In traditional organic rice culture practices, control of weeds is a big problem. This study was conducted to increase the rice production. Results showed that Plant height, SPAD, root length and weight were higher in pot raised seedling than broadcasting method except number of panicles. High plant density caused reduction in plant height, number of culm and chlorophyll content of the rice. No lodging was observed in both methods. Thickness of third internode and culm length was more in pot raised seedlings at both sites. When organic material was used rice yield increased by 3.81%. Higher rice production (10%) was recorded in the fields planted with pot raised seedlings. From the above study it could be conclude that the pot raised seedlings perform better than the seedlings raised by broadcasting methods.

• Korean Journal of Environment and Ecology
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• v.27 no.3
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• pp.305-315
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• 2013

This study is aimed to provide the preliminary data for conservation and management of wintering site for Anser fabalis population in Cheongna Area, Incheon Free Economic Zone, Korea through analyzing the relationship between the biotop structure of its wintering site and behavior characteristics. The main types (size and ratio) of the biotope in Cheongna Area, Incheon Free Economic Zone are reed wetlands ($6,093,762m^2$, 47.8%), rice fields without rice straw ($2,927,916m^2$, 23.0%), and rice fields with rice straw ($1,915,655m^2$, 15.0%). According to the survey carried on 13th Feb., 2013, total 33 species and 6, 535 individual birds were observed and among of them, the dominant bird was Anser fabalis showing 5,128 indiviuals, 78% of total population. As the result of analyzing the migratory route of Anser fabalis, the bird moved from roosting site to foraging site before and after sunrise and from feeding site to roosting site before and after sunset. According to the analysis of interrelation between habitat characteristics and biotope types of the bird, population density was the highest in reed wetlands among habitat types and individual appearance was the highest in water-filled rice field melting ice. The bird ate the roots and bulb of hydrophytes in reed wetlands and showed various behaviors like eating dropped grains, resting and sleeping in water-filled rice fields and eating dropped grains and resting in rice fields with and without rice straw. It is shown that the number of Anser fabalis appearing in rice fields is depended on the presence of dropped grains than types of rice field.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.6
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• pp.473-478
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• 2003

This study was conducted to clarify the effects of duck free-ranging time on the growth and behavior patterns of duck, pH and dissolved oxygen of irrigation water, and growth and yield of the rice plants in paddy fields. Two paddy fields with each 5 aye were used for 12 hours duck free-ranging plot (12HFR) and 24 hours duck free-ranging plot(24HFR). Body weight gain of the duck was not different between 12HFR and 24HFR. Eating and feather grooming behavior in the 12HFR were significantly longer than those of 24HFR, but other behavior patterns were not so. Working behavior and activities of duck in paddy fields tended to be longer in the 12HFR than in 24HFR. However, any difference was not found on staying time of duck in paddy fields. Although it was not statistically significant, pH and dissolved oxygen of irrigation water tended to be higher in the 12HFR than in 24HFR. The plant height of rice in the 12HFR was significantly shorter than that of 24HFR during the latter half period. The number of tillers per hill was significantly increased in the 24HFR than in 12HFR. The shoot dry weight of rice in the 12HFR was significantly less than in the 24HFR during the heading stage of rice plant, but the root dry weight was not different. The number of spikelets per panicle was significantly less in the 12HFR than in 24HFR, however the percentage of ripened grains was significantly higher in the 12HFR. The yield of rice was not significantly different between the treatments. In conclusion, the free-ranging time of duck for 12 hours in paddy fields promoted eating and working behavior of the ducks. Free-ranging time did give effects on rice traits such as the number of tillers per hill, plant height, shoot dry weight of the rice plant, and spikelet number and percentage of ripened grain. However, the duck growth, pH and dissolved oxygen of irrigation water, and paddy rice yield were not affected by duck free-ranging time. These results might suggest that almost same effect as in 24 hours of free-ranging can be obtained with only 12 hours of free-ranging in daytime.

• The Plant Pathology Journal
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• v.38 no.1
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• pp.46-51
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• 2022

Rice blast is the most destructive disease threatening stable rice production in rice-growing areas. Cultivation of disease-resistant rice cultivars is the most effective way to control rice blast disease. However, the rice blast resistance is easy to breakdown within years by blast fungus that continually changes to adapt to new cultivars. Therefore, it is important to continuously monitor the incidence of rice blast disease and race differentiation of rice blast fungus in fields. In 2020, a severe rice blast disease occurred nationwide in Korea. We evaluated the incidence of rice blast disease in Yeoju and compared the weather conditions at the periods of rice blast disease in 2019 and 2020. We investigated the races and avirulence genes of rice blast isolates in Yeoju to identify race diversity and genetic characteristics of the isolates. This study will provide empirical support for rice blast control and the breeding of blast-resistant rice cultivars.