• Environmental and Resource Economics Review
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• v.10 no.1
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• pp.95-126
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• 2001

Functional values for wastewater treatment and atmospheric regulation in coastal wetland and rice paddy ecosystems are quantified, and an illustration is given on how to integrate biophysical parameters into a valuation framework. This is one of most controversial issues in economic analysis for wetland preservation versus wetland conversion to agricultural use. This paper includes theoretical considerations for estimating functional values of environmental ecosystems, and the integration of biophysical data and replacement cost method employed. Specific physical and geographical characteristics and data on ecosystem functions and services in coastal wetlands and rice paddies are addressed for evaluating their values in economic terms. In particular this paper indicates double counting problems and overestimation in the previous studies, and demonstrates how to avoid them and to maintain the consistency of valuation process involving a least-cost method, thus enables an accurate integration of the coastal wetland ecology and wetland economics. As a result which is far away from the previous studies, the total economic present value of wastewater assimilation by coastal wetland is estimated at 7,484,640 won/ha, and the net present value of positive effect for atmospheric regulation, negative effects for air pollution and water pollution by rice paddy is estimated at -37,934 won/ha, assuming that resources are infinitely long-lived and the annual value and the rate of discount (10%) is constant every year. In conclusion, for further reliability and validity of functional values for natural resources it is very noteworthy that a general equilibrium framework that could directly incorporate the interdependence between ecosystem functions and services would be preferred to the partial equilibrium framework.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.757-759
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• 2003

Understanding the area of the rice paddy fields is important, and suitable for it the remote sensing. SAR is effective to the monitor in Southeast Asia with the rainy season. The detection of the filled rice paddy fields by RADARSAT was tried in the north part of Bangkok Thailand, and in the Mekong river valley Cambodia, which ware the main rice production country in Southeast Asia. We get observation data by RADARSAT and fields all through a year around Bangkok. However, because the flood had occurred on the study area in 2002 observed, the detection only of the rice fields ware difficult.

• Asian Journal of Atmospheric Environment
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• v.11 no.3
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• pp.202-216
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• 2017

Nitrogen (N) is an essential macronutrient. Thus, evaluating its flows and stocks in rice paddy ecosystems provides important insights into the sustainability and environmental loads of rice production. Among the N sources of paddy fields, atmospheric deposition and irrigation inputs remain poorly understood. In particular, insufficient information is available for atmosphere-rice paddy exchange of gaseous and particulate reactive N (Nr, all N species other than molecular N) which represents the net input or output through dry deposition and emission. In this study, we assessed the N inputs via atmospheric deposition and irrigation to a Japanese rice paddy area by weekly monitoring for 2 years with special emphasis on gas and particle exchange. The rice paddy during the cropping season acted as a net emitter of ammonia ($NH_3$) to the atmosphere regardless of the N fertilizer applications, which reduced the effects of dry deposition to the N input. Dry N deposition was quantitatively similar to wet N deposition, when subtracting the rice paddy $NH_3$ emissions from N exchange. The annual N inputs to the rice paddy were 3.2 to $3.6\;kg\;N\;ha^{-1}\;yr^{-1}$ for exchange, 8.1 to $9.8\;kg\;N\;ha^{-1}\;yr^{-1}$ for wet deposition, and 11.1 to $14.5\;kg\;N\;ha^{-1}\;yr^{-1}$ for irrigation. The total N input, 22.8 to $27.5\;kg\;N\;ha^{-1}\;yr^{-1}$, corresponded to 38% to 55% of the N fertilizer application rate and 53% to 67% of the brown rice N uptake. Monitoring of atmospheric deposition and irrigation as N sources for rice paddies will therefore be necessary for adequate N management.

• Ecology and Resilient Infrastructure
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• v.2 no.3
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• pp.247-254
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• 2015

Changes in land-use type can affect soil and water properties in stream ecosystems. This study examined the effects of different land-use types on biogeochemical properties and microbial activities of a stream. We collected water and sediment samples in a stream at three different sites surrounded by varying land-use types; a forest, a radish field and a rice paddy. Nitrogen contents, such as nitrate, nitrite and total nitrogen in the stream water body, showed significant differences among the sampling sites. The highest nitrogen values were recorded at the site surrounded by cropland, as fertilizer runoff impacted the stream. Soil organic matter content in the sediment showed significant differences among sites, with the highest content exhibited at the forest mouth site. These differences might be due to the organic matter in surrounding terrestrial ecosystems. Microbial activities determined by extracellular enzyme activities showed similar values throughout all sites in the water body; however, the activities in the sediments exhibited the highest values near the forest site and mirrored the soil organic matter content values. From these results, we conclude that different land-use types are important factors affecting water and sediment properties in stream ecosystems.

• Journal of Microbiology and Biotechnology
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• v.32 no.10
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• pp.1292-1298
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• 2022

Soil autotrophic bacterial communities play a significant role in the soil carbon (C) cycle in paddy fields, but little is known about how rhizosphere soil microorganisms respond to different long-term (35 years) fertilization practices under double rice cropping ecosystems in southern China. Here, we investigated the variation characteristics of rhizosphere soil RubisCO gene cbbL in the double rice ecosystems of in southern China where such fertilization practices are used. For this experiment we set up the following fertilizer regime: without any fertilizer input as a control (CK), inorganic fertilizer (MF), straw returning (RF), and organic and inorganic fertilizer (OM). We found that abundances of cbbL, 16S rRNA genes and RubisCO activity in rhizosphere soil with OM, RF and MF treatments were significantly higher than that of CK treatment. The abundances of cbbL and 16S rRNA genes in rhizosphere soil with OM treatment were 5.46 and 3.64 times higher than that of CK treatment, respectively. Rhizosphere soil RubisCO activity with OM and RF treatments increased by 50.56 and 45.22%, compared to CK treatment. Shannon and Chao1 indices for rhizosphere soil cbbL libraries with RF and OM treatments increased by 44.28, 28.56, 29.60, and 23.13% compared to CK treatment. Rhizosphere soil cbbL sequences with MF, RF and OM treatments mainly belonged to Variovorax paradoxus, uncultured proteobacterium, Ralstonia pickettii, Thermononospora curvata, and Azoarcus sp.KH33C. Meanwhile, cbbL-carrying bacterial composition was obviously influenced by soil bulk density, rhizosphere soil dissolved organic C, soil organic C, and microbial biomass C contents. Fertilizer practices were the principal factor influencing rhizosphere soil cbbL-carrying bacterial communities. These results showed that rhizosphere soil autotrophic bacterial communities were significantly changed under conditions of different long-term fertilization practices Therefore, increasing rhizosphere soil autotrophic bacteria community with crop residue and organic manure practices was found to be beneficial for management of double rice ecosystems in southern China.

• Korean Journal of Agricultural and Forest Meteorology
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• v.18 no.4
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• pp.337-347
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• 2016

Carbon dioxide ($CO_2$) and methane ($CH_4$) were measured in a rice-barley double cropping and rice mono cropping paddy fields, which are located in the southwestern coast of Korea, over a one-year period. Net ecosystems $CO_2$ exchange (NEE) and ecosystem respiration (Re) were estimated by the eddy covariance (EC) method, and an automatic open/close chamber (AOCC) method was used to measure $CH_4$ fluxes. Environmental factors (solar radiation, air temperature, precipitation etc.) were also measured along with fluxes. After the quality control and gap-filling, the observed fluxes were analyzed. As a result, NEE was -603.0 and $-471.5g\;C\;m^{-2}\;yr^{-1}$ in rice-barley double cropping and rice mono cropping paddy field, respectively. $CH_4$ emissions increased during the course of flooded days and were similar in two cropping paddy field. Accoding to rough results considering only fluxes of $CO_2$ and $CH_4$, it was estimated that the carbon absorbation in rice-barley double cropping paddy field was higher than that in rice mono cropping paddy field by $128.9g\;C\;m^{-2}\;yr^{-1}$.

• Korean Journal of Environmental Biology
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• v.38 no.2
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• pp.222-230
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• 2020

Temperature-dependent development models for Hydrochara affinis were built to estimate the ecological parameters as fundamental research for monitoring the impact of climate change on rice paddy ecosystems in South Korea. The models predicted the number of lifecycles of H. affinis using the daily mean temperature data collected from four regions (Cheorwon, Dangjin, Buan, Haenam) in different latitudes. The developmental rate of each life stage linearly increased as the temperature rose from 18℃ to 30℃. The goodness-of-fit did not significantly differ between the models of each life stage. Unlike the optimal temperature, the estimated thermal limits of development were considerably different among the models. The number of generations of H. affinis was predicted to be 3.6 in a high-latitude region (Cheorwon), while the models predicted this species to have 4.3 generations in other regions. The results of this study can be useful to provide essential information for estimating climate change effects on lifecycle variations of H. affinis and studies on biodiversity conservation in rice fields.

• Journal of Korean Society of Rural Planning
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• v.27 no.2
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• pp.49-58
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• 2021

Rural and agricultural landscapes are important forms of land use in maintaining biodiversity. In addition humans are provided with various public functions from ecosystems and agricultural ecosystems. But the creation of a facility horticultural complex can be a space that can undermine the public interest function of the agricultural ecosystem. Therefore, this study aims to quantify the function of ecosystem services that land use changes affect biodiversity in Korea's rice paddy fields. The area subject to the study was selected as the largest agricultural complex in Korea due to rice paddy fields and land use changes, and field agriculture was also carried out simultaneously. The survey was conducted only in the fields of vegetation, insects, amphibians, and birds, four areas of biodiversity that are believed to have a high impact on changes in land use in agricultural landscapes. The valuation of ecosystem services in four areas of biodiversity derived from this study was evaluated as non-market value. As a result of quantitative evaluation, about 25 species of vegetation were reduced due to changes in land use. The diversity of about 40 species of aquatic insects that inhabit rice paddies among insects has disappeared due to the creation of a horticultural complex. Birds and amphibian reptiles were also found to have decreased diversity and populations. This research is expected to be used in various ways to develop policies to enhance ecosystem service functions.

• Korean Journal of Environmental Agriculture
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• v.39 no.4
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• pp.334-342
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• 2020

BACKGROUND: To quantify carbon exchange at agricultural ecosystems in South Korea, net ecosystem exchange (NEE) at three croplands including a rice paddy, a bean field and an apple orchard was measured on the basis of the eddy covariance technique. METHODS AND RESULTS: NEE of CO2 during the growing season (June to September) averaged over the recent two years (2018-2019) was the highest at rice (-4.49 g C m-2 day-1), followed by the bean (-3.12 g C m-2 day-1) and apple (-0.93 g C m-2 day-1). The diurnal variation of NEE was the highest at the rice, while the seasonal variation of it was the highest at the bean than others. In terms of yearly variation, the rice paddy and the bean field absorbed more CO2 in 2019 compared to 2018, while the apple orchard absorbed less. CONCLUSION: Our results confirmed that these croplands consistently acted as net sinks for CO2 during the growing season because an amount of CO2 uptake from photosynthesis was larger than one of its emissions from respiration. The quantification of net CO2 exchange at agricultural ecosystems may help to better understand the local carbon cycle over various time scales.

• Proceedings of the Korean Society of Crop Science Conference
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• 1998.10a
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• pp.210-232
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• 1998

Tong-il, the high-yielding rice variety bred on early 1970, effected a turning point in modern rice production in Korea. As rice production reached the highest record yield in 1978 with HYV, Korea achieved self-sufficiency in domestic supply of rice (or the first time in (her own) history, HYV required high input of fertilizers and pesticides for proving its yielding ability and needed new techniques such as early nursery-planting to prevent chilling damage. But, farm economy did not follow the successful achievement of rice production because of increased farming cost and inflation.'Tong-il variety has been replaced by new high-yielding Japonica varieties from 1980 when record-low-temperature during summer months had persisted. Also, the cooked rice of Tong-il variety did not agree with the appetite of Korean people. Though the hectarage of Tong-il rice did reduce, farmers applied the same high-input cultural techniques for new Japonica cultivars as did for Tong-il variety. Heavy application of nitrogen fertilizer contaminated surface and ground water with nitrate ions while phosphorous fertilizer was blamed for algae pollution. Frequent spray of pesticide and herbicide reduced significantly the biotic population in paddy ecosystems including insects and soil microorganisms. The new technologies of the 21st century must be directed to produce safe food, to save natural resources, and to preserve a clean environment for human welfare. We need low-input sustainable farming techniques to provide high-yielding crops and to preserve a healthy ecosystem.