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Characteristics of Rice and Paddy Soil under No-Till Direct-Sown Rice-Wheat Cropping System

  • Cho, Young-Son;Choe, Zhin-Ryong;Lee, Byeong-Zhin
    • Korean Journal of Organic Agriculture
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    • v.7 no.2
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    • pp.153-161
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    • 1999

  • No-till direct-sown rice-wheat relaying cropping system has major advantages such as labor and cost saving by eliminating tillage and preparation of seed bed and transplanting. In this system, rice sowing was done simultaneously wheat harvesting. A paddy field experiment was conducted to evaluate effects of no-till years on soil microbial changes and soil physico-chemical characteristics with rice growth and development. Chemical fertilizers and agricultrual chemicals was not applied in no-till system. As the year in no-till direct-sown system the air permeability was increased and after water submerging soluble nitrogen was released Aerobic microbial-n was highest in May and then decreased after water irrigation. The population of aerobic soil microorganisms were steeply decreased after water submerging Soil microorganisms was decreased with the increased the soil depth. A month was needed for the seedling establishment in a no-tillage rice-wheat cropping system. Increased cropping years improved leaf greenness and leaf area index(LAI). But stomatal conductance(Gc) was higher in conventional cultivation system than no-till system. Stomatal conductance at panicle initiation stage was increased higher in conventional condition of leaves but the difference between conventional and no-till system was increased at heading stage. In no-till 4 years condition rice grain yield was spikelet numbers per panicle.

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A Study on the Variation of Hazardous Pollutant Emissions in Korea from 2006 to 2015 (2006~2015년 동안 국내 유해화학물질 배출량 변화에 관한 연구)

  • Im, JiYoung;Kim, HyunJi;Kim, MinSun;Lee, JiHo;Lee, SangMok;Lee, ChungSoo
    • Journal of Environmental Health Sciences
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    • v.44 no.1
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    • pp.15-23
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    • 2018

  • Objectives: The purpose of this study was to investigate the changes in hazardous pollutant emissions in Korea over the period of 2006-2015. Methods: A survey of hazardous pollutant emissions was conducted through the homepage for 2006-2015. The emission of hazardous chemicals and the health effect was examined using the Annual Report of Air Quality in Korea (2016) and National Health Statistics (2015) as references. Results: Hazardous pollutant emissions increased by 1.1 times over the past decade, and the circulation amount of chemicals was 15% compared to the previous year. $PM_{10}$ concentrations showed a tendency to decrease, but emissions have not declined. In addition, asthma and atopic dermatitis correlated with similar emissions, but allergic disease showed no connection. Conclusion: These results on hazardous pollutant emissions indicate that they have increased. However, no association between emissions and health effects was shown, so more research is needed.

  • https://doi.org/10.5668/JEHS.2018.44.1.15 인용 PDF KSCI

Kinetics of Hydrogen Rich Ethanol as Reductant for HC-SCR over $Al_2O_3$ Supported Ag Catalyst (Ag/$Al_2O_3$ 촉매하의 HC-SCR에서 수소 풍부 에탄올의 반응 특성)

  • Lee, Ju-Heon;Park, Jeong-Whan;Kim, Seong-Soo;Yoo, Seung-Joon;Kim, Jin-Gul
    • Transactions of the Korean hydrogen and new energy society
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    • v.21 no.6
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    • pp.519-525
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    • 2010

  • Ethanol was used as reductant to remove $NO_x$ over Ag/$Al_2O_3$ catalyst via SCR from stationary emission source. Among the tested hydrocarbon reductants, ethanol showed highest de-$NO_x$ performance over the Ag/$Al_2O_3$ catalyst. De-$NO_x$ efficiency of about 83% was obtained in the condition of GHSV 20,000 $hr^{-1}$, $NO_x$ 200 ppm, CO 200 ppm, $O_2$ 13%, $H_2O$ 5% and mole ratio of ethanol/$NO_x$ = 2 between temperature of $300^{\circ}C$ and $400^{\circ}C$. While $SO_2$ presence in the $NO_x$ exhaust suppressed the catalytic activity, catalyst with acid (0.7% $H_2SO_4$) treatment of catalyst showed higher catalytic activity, where In-Situ DRIFT showed S presence over catalyst surface was increased after acid treatment of catalyst. From in-situ DRIFT and SCR results, it was concluded that sulfur presence over the surface of Ag/$Al_2O_3$ catalyst was the dominant factor to control the de-$NO_x$ reaction yield via HC-SCR from the exhausted gas including $SO_2$.

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Selective Catalytic Reduction of Nitric Oxide over Metal Exchanged ZSM-5 Catalysts (금속을 이온교환시킨 ZSM-5 촉매 상에서 Nitric Oxide의 환원반응)

  • Ahn, Sung-Hwan;Kim, Tae-Ok;Hahm, Hyun-Sik
    • Journal of the Korean Applied Science and Technology
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    • v.17 no.1
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    • pp.1-5
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    • 2000

  • The selective catalytic reduction(SCR) of nitric oxide by ethane in the presence of oxygen was investigated on Cu-ZSM-5, Co-ZSM-5 and Ga-ZSM-5 catalysts over a range of 400, 450 and $500^{\circ}C$. The catalysts were prepared by ion-exchange method. The composition of the reactant gases were 1000 ppm of NO, 1000 ppm of $C_{2}H_{6}$ and 2.5% of $O_{2}$, and the reaction was conducted in a fixed-bed reactor at 1 atm. For the 20wt% Co-ZSM-5(50) catalyst, the NO conversion reached up to 100%, while the $C_2H_6$ conversion and the CO selectivity were about 50% and 25%, respectively, at $450^{\circ}C$. For the 20wt% Cu-ZSM-5(50) catalyst, the NO conversion and the C2H6 conversion were about 80% and 100%, respectively, but there was no CO produced. The metal ion-exchanged ZSM-5 catalysts exhibited a tendency to increase the NO conversion with the Si/Al ratio of the ZSM-5, that is, NO conversion was inversely proportional to the acidity of the catalysts. But, the effect of the acidity on NO conversion was not so large. From the XRD results of the catalysts before and after SCR reaction it was found that there was no structural change.

  • https://doi.org/10.12925/jkocs.2000.17.1.1 인용 PDF