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Korean Journal of Environmental Agriculture

p-ISSN 1225-3537
e-ISSN 2233-4173

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  • View304

    Desalinization Effect of Off-season Crop Cultivation in Long-term Oriental Melon Cultivated Plastic Film House Soils

    Il-Su Byeon, Jong-Bae Chung / Korean Journal of Environmental Agriculture / 2015 / v.34, no.4, 253-259

    http://dx.doi.org/10.5338/KJEA.2015.34.4.39
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    BACKGROUND:

    During the off-season, the cultivation of Chinese cabbage and water dropwort is often used to desalinize plastic film house soils. The objective of this study was to verify the effect of double-cropping systems on the salt removal in oriental melon cultivated plastic film house soils.

    METHODS AND RESULTS:

    Electrical conductivity (EC) and soluble salt contents were measured in soils collected from plastic film houses of oriental melon cultivation before and after the off-season crop cultivation. Also the same measurements were performed in the next oriental melon season to estimate the desalinization effect of double-cropping systems. During the cultivation of Chinese cabbage under open-field condition, ECe of surface soil was reduced from 6.0 to 0.8 dS/m. Double-cropping of water dropwort in flooded soil was also efficient in removing the salts accumulated during oriental melon cultivation. In the house soils where salts were removed during the off-season crop cultivation, soil ECe was maintained below 3 dS/m during the next oriental melon cultivation season.

    CONCLUSION:

    The off-season cropping under open-field or flooded condition was effective in desalinization of plastic film house soils. Since the salt removal effect is not expected to last for several years, the double-cropping system should be introduced every season to maintain soil EC below the critical level.

  • View242

    The applicability of burcucumber (Sicyos angulatus L.) as a substitute for nitrogen fertilizer

    Min-Suk Kim, Hyungi Min, Sun-Hee Hong, Jeong-Gyu Kim / Korean Journal of Environmental Agriculture / 2016 / v.35, no.1, 1-5

    http://dx.doi.org/10.5338/KJEA.2016.35.1.06
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    BACKGROUND:

    Burcucumber(Sicyos angulatus L.) is an invasive plant species and disturbs ecosystems in Korea. The main method for prevention of burcucumber is cutting or pulling out. However, the studies accounting for the use of the by-product of burcucumber after cutting remain incomplete. Thus, the aim of this study was to investigate the applicability of burcucumber as a substitute for nitrogen fertilizer.

    METHODS AND RESULTS:

    Burcucmber plants only including stem, leaves, and petiole were collected from the Sky Park in Seoul and divided in to three categories based on the length of stem of burcucumber; 10-30 cm, 30-100 cm, and 100-200 cm. And they were input into soil with 20 kg-N/10 a. After 4 weeks aging, chemical properties of treated soils and the productivity of lettuce(Lactuca sativa L.) were examined. Both the inorganic nitrogen contents in soils and the growth of lettuce were increased with the decreases in length of burcucumber standing for young plant. And the inorganic nitrogen content and the productivity of lettuce were positively correlated(r= 0.9409).

    CONCLUSION:

    The C/N ratio of burcucumber was low, indicating fast decomposition and nitrogen supplying rate, resulting in the increase in lettuce growth. Burcucumber could be a good substitute for nitrogen organic fertilizer.

  • View189

    A Research of Soil Environmental Health in Urban Garden, Gwangju

    Gil-Sik Jang, Yun-Hee Kim, Young-Seop Choi, Seung-Ho Kim, Jong-Min Kim, Seok-Jin Bae, Young-Gwan Cho, Tae-Hyoung Koo / Korean Journal of Environmental Agriculture / 2016 / v.35, no.2, 87-96

    http://dx.doi.org/10.5338/KJEA.2016.35.2.14
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    BACKGROUND:

    The objective of this study is to evaluate the soil quality to cultivate crops in urban garden.

    METHODS AND RESULTS:

    During the period of six month from March to August 2015, measured eight heavy metals, seven Organic items and Fluorine on seventeen urban sites and thirty-one suburban sites in Gwangju city.

    METHODS AND RESULTS:

    The average concentration and range of heavy metal in soil are 0.15 mg/kg(ND-0.6) for Cd, 14.9 mg/kg(1.5-33.3) for Cu, 4.4 mg/kg(0.4-71.8) for As, 0.05 mg/kg(ND-1.366) for Hg, 24.7 mg/kg(13.1-62.7) for Pb, 102.5 mg/kg(49.1-276.4) for Zn and 9.2 mg/kg(ND-90.1) for Ni but Cr6+ is not detected. The average value and range of soil fertility items are 253.5mg/kg(76.6-1766.0) for fluorine, 6.4(4.8-7.7) for pH, 20.3 g/kg(5.0-44.0) for orangic matters, 562.7 mg/kg (28.0-1672.0) for available phosphate, 0.6 cmol+/kg (0.1-2.3) for K, 9.7 cmol+/kg (2.7-22.0) for Ca, 3.0 cmol+/kg (0.9-7.4) for Mg, 1.0 ds/m(0.2-2.9) for conductivity. The concentration of Hg in Suburban area is 0.005 mg/kg lower than 0.134 mg/kg in urban area. Also, the concentration of As, Cd, Ni and Zn is lower than urban area as 32%, 37%, 51%, 71% respectively.

    CONCLUSION:

    According to SPI index of soil contamination, 39 sites are first degree and 8 sites are second degree and 1 site(41th) is fourth degree. Pb and Cd are not detected and As is detected tiny amounts in plants grown polluted soil, so heavy metals have not moved to plants.

  • View182

    Adsorption Characteristics of Aqueous Ammonium Using Rice hull-Derived Biochar

    Yong-Su Choi, Joung-Du Shin, Sun-Il Lee, Sung-Chul Kim / Korean Journal of Environmental Agriculture / 2015 / v.34, no.3, 155-160

    http://dx.doi.org/10.5338/KJEA.2015.34.3.25
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    BACKGROUND

    Objective of this study was to investigate adsorption characteristics of NH4-N to biochar produced from rice hull in respective to mitigation of greenhouse gases.

    METHODS AND RESULTS

    NH4-N concentration was analyzed by UV spectrophotometer. For adsorption experiment of NH4-N to biochar, input amount of biochar was varied from 0.4 to 10 g/L with 30 mg/L NH4-N solution. Its adsorption characteristic was investigated with application of Langmuir isotherm. Adsorption amount and removal rates of NH4-N were decreased at 53.9% and increased at 20.2% with 10 g/L compared to 0.4 g/L, respectively. The sorption of NH4-N to biochar produced from rice hull was fitted well by a Langmuir model. The largest adsorption amount of NH4-N (qm) and binding strength constant (b) were calculated as 0.4980 mg/g, and 0.0249 L/mg, respectively. It was observed that dimensionless constant (RL) was 0.58.

    CONCLUSION

    It was indicated that biochar produced from rice hull is favorably absorbed NH4-N, because this value lie within 0<RL<1.

  • View134

    Development and Validation of an Analytical Method for β-Agonists in Livestock and Fishery Products Using LC-MS/MS

    Tae Ho Lee, Yu Ra Kim, Su Jeong Park, Ji Young Kim, Jang Duck Choi, Gui Im Moon / Korean Journal of Environmental Agriculture / 2022 / v.41, no.2, 135-151

    https://doi.org/10.5338/KJEA.2022.41.2.17
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    BACKGROUND:

    The β-agonists known as phenyl ethanolamine derivatives have a conjugated aromatic ring with amino group. They are used as tocolytic agents and bronchodilator to human and animal generally, and some of them are used as growth promoters to livestock.

    METHODS AND RESULTS:

    β-agonists in samples were extracted by 0.4 N perchloric acid and ethyl acetate. The target compounds were analyzed by liquid chromatography-electrospray tandem mass spectrometry (LC-ESI-MS/MS). Validation of method was performed according to CODEX guidelines (CAC/GL-71). The matrix matched calibration gave correlation coefficients>0.98, and the obtained recoveries were in the range of 62.0-109.8%, with relative standard deviation ≤ 20.1%. In addition, a survey was performed to inspect any residual β-agonist from 100 samples of livestock and fishery products and ractopamine was detected in one of the 100 samples.

    CONCLUSION(S):

    In this study, we established the analytical method for β-agonists through using the expanded target compounds and samples. And we anticipate that the established method would be used for analysis to determine veterinary drug residues in livestock and fishery products.

  • View124

    Effect of Rice Straw on Methane Production Potential of Cow Manure

    So Yun Park, Jeong A Jang, Xin Zhao, Jin-Kyung Hong, Eun Hea Jho / Korean Journal of Environmental Agriculture / 2022 / v.41, no.2, 71-81

    https://doi.org/10.5338/KJEA.2022.41.2.10
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    BACKGROUND:

    Animal manures are one of the biggest sources of greenhouse gases and improper manage-ment of animal wastes contributes to the increasing greenhouse gases in the atmosphere. Con-verting greenhouse gases generated from animal manures to energy is one way of contributing to the net-zero carbon emissions.

    METHODS AND RESULTS:

    The potential for methane production from cow manure (CM) was studied by measuring the methane yield using the biochemical methane potential (BMP) test. In particular, the effect of co-digestion using rice straw (RM) on the methane production was studied. The methane yields from the co-digestion of CM and RS were statistically similar to that from the mono-digestion of CM or RS. But there was a synergy effect at the CM:RS ratio of 1:2 and 1:1. This can be attributed to the increased C/N ratio. The changed microbial community structure with the addition of substrates (CM, RS) probably led to the increase in the methane produc-tion.

    CONCLUSION(S):

    The methane production potential of the particular CM used in this study was not improved by the addition of RS as a co-substrate. The addition of substrates to the anaerobic sludge promoted the increase in the microbial species having synergetic relationship with methano-gens, and this can partially explain the increase in the methane production with the addition of substrates. Overall, there are needs for further studies to improve the methane yield from CM.

  • View108

    Effect of Non-indigenous Bacterial Introductions on Rhizosphere Microbial Community

    Kathyleen Nogrado, Gwang-Su Ha, Hee-Jong Yang, Ji-Hoon Lee / Korean Journal of Environmental Agriculture / 2021 / v.40, no.3, 194-202

    https://doi.org/10.5338/KJEA.2021.40.3.23
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    BACKGROUND:

    Towards achievement of sustainable agriculture, using microbial inoculants may present promising alternatives without adverse environmental effects; however, there are challenging issues that should be addressed in terms of effectiveness and ecology. Viability and stability of the bacterial inoculants would be one of the major issues in effectiveness of microbial pesticide uses, and the changes within the indigenous microbial communities by the inoculants would be an important factor influencing soil ecology. Here we investigated the stability of the introduced bacterial strains in the soils planted with barley and its effect on the diversity shifts of the rhizosphere soil bacteria.

    METHODS AND RESULTS:

    Two different types of bacterial strains of Bacillus thuringiensis and Shewanella oneidensis MR-1 were inoculated to the soils planted with barley. To monitor the stability of the inoculated bacterial strains, genes specific to the strains (XRE and mtrA) were quantified by qPCR. In addition, bacterial community analyses were performed using v3-v4 regions of 16S rRNA gene sequences from the barley rhizosphere soils, which were analyzed using Illumina MiSeq system and Mothur. Alpha-and beta-diversity analyses indicated that the inoculated rhizosphere soils were grouped apart from the uninoculated soil, and plant growth also may have affected the soil bacterial diversity.

    CONCLUSION:

    Regardless of the survival of the introduced non-native microbes, non-indigenous bacteria may influence the soil microbial community and diversity.

  • View87

    Effect of Phosphate Application on Cadmium Extractability and its Uptake by Rice Cultivated in Contaminated Paddy Soil

    Hyun Ho Lee, Keun Ki Kim, Yong Bok Lee, Youn Sig Kwak, Suk Chul Kim, Sang-beom Lee, Chang Ki Shim, Chang Oh Hong / Korean Journal of Environmental Agriculture / 2016 / v.35, no.4, 235-240

    https://doi.org/10.5338/KJEA.2016.35.4.35
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    BACKGROUND:

    To determine effect of phosphate (P) application on Cadmium (Cd) extractability and its uptake by rice plant in Cd contaminated paddy soil, dipotassium (K2HPO4) which was the most effective of P materials to decrease Cd extractability in previous study was selected as P fertilizer.

    METHODS AND RESULTS:

    Dipotassium phosphate was applied at the rates of 0, 78, 234, and 390 kg P2O5/ha, and then rice was cultivated in submerged paddy soil from Jun. to Oct. in 2015. Cadmium concentrations in grain, straw, and root of rice plant decreased significantly with increasing application rate of K2HPO4. The trend of 1 M NH4OAc extractable Cd concentration in soil was similar to that of Cd uptake by rice plant. One M NH4OAc extractable Cd concentration was negatively related to soil pH and negative charge. Alleviation of Cd phytoavailability of rice in paddy soil might be attributed to increase in pH and negative charge of soil. Using a quadratic response model, amount of grain yield were related to K2HPO4 application rates as Grain yield = 5.38 + 2.39 ×10-3 K2HPO4 – 6.65 × 10-6 K2HPO4 2 (model R2 = 0.968). Using this equations, the greatest grain yield (5.6 Mg/ha) was at the rate of 180 kg P2O5/ha. At this application rate of P, the Cd concentration in grain was 0.53 mg/kg, implying ca. 23% lower than the control.

    CONCLUSION:

    From the view point of heavy metal safety and crop productivity, it might be good P management to apply P fertilizer with 4 times higher rate than recommendation (45 kg/ha).

  • View84

    Pollutant Runoff Reduction Efficiency of Surface Cover, Vegetative Filter Strip and Vegetated Ridge for Korean Upland Fields: A Review

    Se-In Park, Hyun-Jin Park, Hye In Yang, Han-Yong Kim, Kwang-Sik Yoon, Woo-Jung Choi / Korean Journal of Environmental Agriculture / 2018 / v.37, no.3, 151-159

    https://doi.org/10.5338/KJEA.2018.37.3.21
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    BACKGROUND:

    In this review paper, the effects of surface cover (SCV), vegetative filter strip (VFS), and vegetated ridge (VRD) on the pollutant runoff from steep-sloping uplands were analyzed to compare the pollutant reduction efficiency in runoff (PRErunoff) of the practices and to investigate how slope and rainfall parameters affect the PRErunoff.

    METHODS AND RESULTS:

    The PRErunoff of SCV, VFS, and VRD for pollutants including suspended solids and biological oxygen demand was compared by analysis of variance. The effect of slope and rainfall parameters on the PRErunoff was explored by either mean comparison or regression analysis. It was found that the PRErunoff differs with the practices due to different pollutant reduction mechanisms of the practices. Though the PRErunoff was likely to be affected by site condition such as slope and rainfall (amount and intensity), more comprehensive understanding was not possible due to the limited data set.

    CONCLUSION:

    The PRErunoff of SCV, VFS, and VRD differed due to the distinctive mechanisms of pollutant removal of the practices. It is necessary to accumulate experimental data across a variety of gradient of slope and rainfall for comprehensive understanding of the effects of the practices on pollutant runoff from steep-sloping uplands.

  • View72

    Effect of Agricultural Practice and Soil Chemical Properties on Community-level Physiological Profiles (CLPP) of Soil Bacteria in Rice Fields During the Non-growing Season

    Jinu Eo, Myung-Hyun Kim, Young Ju Song / Korean Journal of Environmental Agriculture / 2019 / v.38, no.4, 219-224

    https://doi.org/10.5338/KJEA.2019.38.4.30
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    BACKGROUND:

    Soil bacteria play important roles in organic matter decomposition and nutrient cycling during the non-growing season. The purpose of this study was to investigate the effects of soil management and chemical properties on the utilization of carbon sources by soil bacteria in paddy fields.

    METHODS AND RESULTS:

    The Biolog EcoPlate was used for analyzing community-level carbon substrate utilization profiles of soil bacteria. Soils were collected from the following three types of areas: plain, interface and mountain areas, which were tested to investigate the topology effect. The results of canonical correspondence analysis and Kendall rank correlation analysis showed that soil C/N ratio and NH4+ influenced utilization of carbon sources by bacteria. The utilization of carbohydrates and complex carbon sources were positively correlated with NH4+ concentration. Cultivated paddy fields were compared with adjacent abandoned fields to investigate the impact of cultivation cessation. The level of utilization of putrescine was lower in abandoned fields than in cultivated fields. Monoculture fields were compared with double cropping fields cultivated with barley to investigate the impact of winter crop cultivation. Cropping system altered bacterial use of carbon sources, as reflected by the enhanced utilization of 2-hydroxy benzoic acid under monoculture conditions.

    CONCLUSION:

    These results show that soil use intensity and topological characteristics have a minimal impact on soil bacterial functioning in relation to carbon substrate utilization. Moreover, soil chemical properties were found to be important factors determining the physiological profile of the soil bacterial community in paddy fields.

  • View71

    Estimation of Ammonia Emission with Compost Application in Plastic House for Leafy Perilla Cultivation

    Sung-Chang Hong, Jin-Ho Kim, Min-Wook Kim / Korean Journal of Environmental Agriculture / 2021 / v.40, no.3, 149-160

    https://doi.org/10.5338/KJEA.2021.40.3.18
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    BACKGROUND:

    Concerns have been raised about the impact of recent high concentrations of fine dust on human health. Ammonia(NH3) reacts with sulfur oxides and nitrogen compounds in the atmosphere to form ultrafine ammonium sulfate and ammonium nitrate (PM2.5). There is a growing need for accurate estimates of the amount of ammonia emitted during agricultural production. Therefore, in this study, ammonia emissions generated from the cultivation of leafy perilla in plastic houses were determined.

    METHODS AND RESULTS:

    Cow manure compost, swine manure compost, and poultry manure compost each at 34.6 ton ha-1, the amount commonly used by farmers in the field, was sprayed on the soil surface. Just after spraying cow manure compost, swine manure compost, and poultry manure compost, the ammonia was periodically measured and analyzed to be 22.5 kg ha-1, 22.8 kg ha-1, and 85.2 kg ha-1, respectively. The emission factors were estimated at 70.0 kg-NH3 ton-N, 62.8 kg-NH3 ton-N, and 234.1 kg-NH3 ton-N, respectively. Most ammonia was released in the two weeks after application of the compost and then the amount released gradually decreased.

    CONCLUSION:

    Therefore, it is necessary to improve the emission factor through a study on the estimation of ammonia emission by type of livestock manure and major farming types such as rice fields and uplands, and to update data on the production, distribution, and sales of livestock manure.

  • View66

    The Study of Soil Chemical Properties and Soil Bacterial Communities on the Cultivation Systems of Cnidium officinale Makino

    Kiyoon Kim, Kyeung Min Han, Hyun-Jun Kim, Kwon Seok Jeon, Chung Woo Kim, Chung Ryul Jung / Korean Journal of Environmental Agriculture / 2020 / v.39, no.1, 1-9

    https://doi.org/10.5338/KJEA.2020.39.1.1
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    BACKGROUND:

    The aim of this study was to investigate the soil chemical properties and soil bacterial community of the cropping system for Cnidium officinale Makino.

    METHODS AND RESULTS:

    The bacterial community was analyzed for the relative abundance and principal coordinated analysis (PCoA analysis) by using by Illumina Miseq sequencing. The correlation analysis between soil chemical properties and soil bacterial community were analyzed by Spearman’s rank correlation and DISTLM analysis. Soil bacterial community (phylum and class) showed two distinct clusters consisting of cluster 1 (first cropping) and cluster 2 (continuous cropping) from 2 different cultivation methods of Cnidium officinale Makino. PCoA and DISTLM analyses showed that soil pH and Ca significantly affected soil bacterial community in cultivation area of Cnidium officinale Makino. In addition, Spearman’s rank correlation showed significant correlation between relative abundance (Acidobacteria and Actinobacteria) and soil factors (soil pH and Ca).

    CONCLUSION:

    The results of this study were considered to be important for determining the correlation between soil properties and soil bacterial community of the cropping method for Cnidium officinale Makino. Furthermore, the results will be helpful to investigate the cause of continuous cropping injury of the Cnidium officinale Makino by examining the changes of soil properties and soil bacterial communities.

  • View63

    Ammonia Gas Emission Factor at different Application Rate of Urea in Chinese Cabbage Cultivation

    Su-Lim Lee, Jae-Hoon Lee, Jun-Suk Rho, Yu-Jin Park, Ah-Young Choi, Sin-Sil Kim, Seul-Rin Lee, Jong-Hwan Park, Dong-Cheol Seo / Korean Journal of Environmental Agriculture / 2022 / v.41, no.1, 41-49

    https://doi.org/10.5338/KJEA.2022.41.1.06
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    BACKGROUND:

    The main source of ammonia in soils, South Korea is agricultural emissions (e.g., fertilizer application and livestock manure), with the recent emission inventories reporting them to be approximately 80% of the total emissions. Ammonia as a pollutant is originated largely from agricultural activity and is an important contributor to air quality issues in South Korea. The importance of ammonia in agricultural land is also emerging. In this study, the characteristics of ammonia emission from Chinese cabbage cultivation fields with application rates of urea sere were evaluated.

    METHODS AND RESULTS:

    The ammonia emission characteristics were investigated at the different urea application rates (0, 160, 320, and 640 kg ha-1) and the ammonia emission factor in the Chinese cabbage cultivation field was calculated. As application rate of urea application increased, ammonia emissions increased proportionally. In 2020 and 2021, cumulative ammonia emissions with urea 320 kg ha-1 treatment were 39.3 and 35.2 kg ha-1, respectively for 2020 and 2021. When urea fertilizer was applied, the ammonia emission factors were 0.1217 and 0.1358 NH4+-N kg N kg-1 in 2020 and 2021, respectively.

    CONCLUSION(S):

    Ammonia emissions increased as application rate of urea increased, and the average ammonia emission factor of the Chinese cabbage cultivation field for two years was 0.129 NH4+-N kg N kg-1.

  • View62

    A Study on the Mitigation of Nitrous Oxide emission with the Horticultural Fertilizer of Containing Urease Inhibitor in Hot Pepper and Chinese Cabbage Field

    Ok Jung Ju, Gap June Lim, Sang Duk Lee, Tae Jin Won, Jung Soo Park, Chang Sung Kang, Soon Sung Hong, Nam Goo Kang / Korean Journal of Environmental Agriculture / 2018 / v.37, no.4, 235-242

    https://doi.org/10.5338/KJEA.2018.37.4.36
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    BACKGROUND:

    About 81% of nitrous oxide (N2O) emissions from agricultural land to the atmosphere is due to nitrogen (N) fertilizer application. Mitigation of N2O emissions can be more effective in controlling biochemical processes such as nitrification and denitrification in the soil rather than decreasing fertilizer application. The use of urease inhibitors is an effective way to improve N fertilizer efficiency and reduce N2O emissions. Several compounds act as urease inhibitors, but N-(n-butyl) thiophosphoric triamide (NBPT) has been used worldwide.

    METHODS AND RESULTS:

    Hot pepper and chinese cabbage were cultivated in five treatments: standard fertilizer of nitrogen-phosphorus-potassium(N-P-K, N-P2O5-K2O: 22.5-11.2-14.9 kg/ha for hot pepper and N-P2O5-K2O: 32.0-7.8-19.8 kg/ha for chinese cabbage), no fertilizer, and NBPT-treated fertilizer of 0.5, 1.0, and 2.0 times of nitrogen basal application rate of the standard fertilizer, respectively in Gyeonggi-do Hwaseong-si for 2 years(2015-2016). According to application of NBPT-treated fertilizer in hot pepper and chinese cabbage, N2O emission decreased by 19-20% compared to that of the standard fertilizer plot.

    CONCLUSION:

    NBPT-treated fertilizer proved that N2O emissions decreased statistically significant in the same growth conditions as the standard fertilization in the hot pepper and chinese cabbage cultivated fields. It means that NBPT-treated fertilizer can be applied for N fertilizer efficiency and N2O emissions reduction.

  • View54

    Study for Residue Analysis of Fluxametamid in Agricultural Commodities

    Ji Young Kim, Yoon Ju Choi, Jong Soo Kim, Do Hoon Kim, Jung Ah Do, Yong Hyun Jung, Kang Bong Lee, Hyochin Kim / Korean Journal of Environmental Agriculture / 2019 / v.38, no.1, 1-9

    https://doi.org/10.5338/KJEA.2019.38.1.5
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    BACKGROUND:

    Accurate and simple analytical method determining Fluxametamid residue was necessary in various food matrices. Additionally, fulfilment of the international guideline of Codex (Codex Alimentarius Commission CAC/GL 40) was required for the analytical method. In this study, we developed Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) method to determine the Fluxametamid residue in foods.

    METHODS AND RESULTS:

    Fluxametamid was extracted with acetonitrile, partitioned and concentrated with dichloromethane. To remove the interferences, silica SPE cartridge was used before LC-MS/MS (Liquid Chromatography-Tandem Mass Spectrometry) analysis with C18 column. Five agricultural commodities (mandarin, potato, soybean, hulled rice, and red pepper) were used as a group representative to verify the method. The liner matrix-matched calibration curves were confirmed with coefficient of determination (r2) greater than 0.99 at calibration range of 0.001-0.25 mg/kg. The limits of detection and quantification were 0.001 and 0.005 mg/kg, respectively. Mean average accuracies were shown to be 82.24-115.27%. The precision was also shown to be less than 10% for all five samples.

    CONCLUSION:

    The method investigated in this study was suitable to the Codex guideline for the residue analysis. Thus, this method can be useful for determining the residue in various food matrices as routine analysis.

  • View53

    Ammonia Adsorption Characteristic of Reusable PAN/zeolite Fibers Made by Electrospinning

    Yeon Hee Ro, Woo Jin Chung, Soon Woong Chang / Korean Journal of Environmental Agriculture / 2020 / v.39, no.4, 281-288

    https://doi.org/10.5338/KJEA.2020.39.4.33
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    BACKGROUND:

    Generally, ammonia occurs from agricultural waste disposal. Ammonia is known as a harmful substance to the human body and has a bad influence such as eutrophication on the ecosystem. It is possible to remove the ammonia by ammonia adsorption method using natural zeolite, without external influence. However, due to the natural zeolite shape, it is hard to reuse.

    METHODS AND RESULTS:

    Electrospinning method can produce fiber with constant diameter. Moreover, electrospinning method has no limitation for selecting the material to make the fiber, and thus, it is valuable to reform the surface of adsorbent. In this study, reusable membrane was made by electrospinning method. The highest removal efficiency was shown from the membrane with 20% of zeolite included, and it has been verified that it is possible to reuse the membrane through chemical treatment. The highest ammonia removal efficiency was about 92.4%.

    CONCLUSION:

    In this study, ammonia adsorption characteristics of zeolite fibers were studied. Electrospinning method can produce zeolite fiber with even distribution. Ammonia can be removed efficiently from ion exchange ability of the natural zeolite. The result of adsorption isotherm indicated that both Freundlich model and Langmuir model provided the best fit for equilibrium data. And study on desorption has demonstrated that the ion exchange from zeolite was reversible when 0.01 M NaCl and KCl solution were used.

  • View52

    Assessment of Electrical Conductivity of Saturated Soil Paste from 1:5 Soil‐Water Extracts for Reclaimed Tideland Soils in South‐Western Coastal Area of Korea

    Hyun‐Jin Park, Hye In Yang, Se‐In Park, Bo‐Seong Seo, Dong‐Hwan Lee, Han‐Yong Kim, Woo‐Jung Choi / Korean Journal of Environmental Agriculture / 2019 / v.38, no.2, 69-75

    https://doi.org/10.5338/KJEA.2019.38.2.15
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    BACKGROUND:

    Measurement of electrical conductivity of saturated soil paste (ECe) for assessment of soil salinity is time‐consuming, and thus conversion of EC of 1:5 soilwater extract (EC1:5) to ECe using a dilution factor may be of help to monitor salinity of huge number of soil samples. This study was conducted to evaluate the dilution factor for reclaimed tideland (RTL) soils of South Korea.

    METHODS AND RESULTS:

    Soil samples (n=40) were collected from four RTLs, and analyzed for EC1:5, ECe, and cation compositions of 1:5 soil‐water extract. The dilution factor (8.70) was estimated by regression analysis between EC1:5 and ECe, and the obtained dilution factor was validated by applying to an independent data set (n=96) of EC1:5 and ECe. The ECe measured and predicted was strongly correlated (r2=0.74, P<0.001), but ECe was overestimated by 16% particularly for the soils with high clay content and low sodium adsorption ratio (SAR).

    CONCLUSION:

    This study suggests that using the dilution factor to convert EC1:5 to ECe is feasible method to monitor changes in the soil salinity of the study RTL. However, overestimation of ECe should be cautioned for the soils with high clay content and low SAR.

  • View48

    Influence of Drought Stress Treatment on Saponarin Content during the Growing Period of Barley Sprouts

    Young-Eun Yoon, Song Yoeb Kim, Hyeonji Choe, Ju Young Cho, Woo Duck Seo, Young-Nam Kim, Yong Bok Lee / Korean Journal of Environmental Agriculture / 2021 / v.40, no.4, 290-294

    https://doi.org/10.5338/KJEA.2021.40.4.33
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    BACKGROUND:

    Barley sprouts contain a large number of secondary metabolites such as polyphenols, saponarin, and policosanols. The synthesis of such secondary metabolites occurs as a defense mechanism against external environmental stresses. In particular, it has been widely known that drought stress (DS) increases the content of flavonoids in plants. The objective of this study was to investigate the effects of drought stress treatment on the saponarin content in barley sprouts during the growing period.

    METHODS AND RESULTS:

    In this study, changes in saponarin content with different DS exposure periods and times were evaluated under the hydroponic system. For establishing different DS treatment periods, water supply was stopped for 1, 2, and 3 days, once leaf length was at 10 cm. To control different DS treatment times, water supply was stopped for 2 days, once leaf lengths were 5, 10, and 15 cm. As a result, the water potential of barley sprouts decreased from -0.8 MPa (before DS treatment) to -1.2, -2.4, and -3.2 MPa (after DS treatment), and reversely recovered to -0.8 MPa after re-irrigation. When 10 cm leaves were subjected to DS for 1 and 2 days, the saponarin content increased by 12 and 10%, respectively, while it increased by 19% when DS was applied to the 5 cm leaves.

    CONCLUSION(S):

    The results of this study suggest that drought stress at the early stage of growth (5 cm) is most helpful to increase the saponarin content of barley sprouts.

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    Effect of KOH Concentrations and Pyrolysis Temperatures for Enhancing NH4-N Adsorption Capacity of Rice Hull Activated Biochar

    HuiSeon Kim, Seok-In Yun, NanHee An, JoungDu Shin / Korean Journal of Environmental Agriculture / 2020 / v.39, no.3, 171-177

    https://doi.org/10.5338/KJEA.2020.39.3.20
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    BACKGROUND:

    Recently, biomass conversion from agricultural wastes to carbon-rich materials such as biochar has been recognized as a promising option to maintain or increase soil productivity, reduce nutrient losses, and mitigate greenhouse gas emissions from the agro-ecosystem. This experiment was conducted to select an optimum conditions for enhancing the NH4-N adsorption capacity of rice hull activated biochar.

    METHODS AND RESULTS:

    For deciding the proper molarity of KOH for enhancing its porosity, biochars treated with different molarity of KOH (0, 1, 2, 4, 6, 8) were carbonized at 600℃ in the reactor. The maximum adsorption capacity was 1.464 mg g-1, and an optimum molarity was selected to be 6 M KOH. For the effect of adsorption capacity to different carbonized temperatures, 6 M KOH-treated biochar was carbonized at 600℃ and 800℃ under the pyrolysis system. The result has shown that the maximum adsorption capacity was 1.76 mg g-1 in the rice hull activated biochar treated with 6 M KOH at 600℃ of pyrolysis temperature, while its non-treated biochar was 1.17 mg g-1. The adsorption rate in the rice hull activated biochar treated with 6 M KOH at 600℃ was increased at 62.18% compared to that of the control. Adsorption of NH4-N in the rice hull activated biochar was well suited for the Langmuir model because it was observed that dimensionless constant (RL) was 0.97 and 0.66 at 600℃ and 800℃ of pyrolysis temperatures, respectively. The maximum adsorption amount (qm) and the bond strength constants (b) were 0.092 mg g-1 and 0.001 mg L-1, respectively, for the rice hull activated biochar treated with 6 M KOH at 600℃ of pyrolysis.

    CONCLUSION:

    Optimum condition of rice hull activated biochar was 6M KOH at 600℃ of pyrolysis temperature.