• Korean Journal of Environmental Agriculture
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• v.42 no.4
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• pp.408-417
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• 2023

This study aimed to investigate the effects of an aquaponics system utilizing catfish recirculating water on the growth and water quality in lettuce and chicory cultivation. After 60 d of catfish cultivation in the BFT-AP, the survival rate was 96.0% and average weight gain was 178.5 g. The WGR grew by 241.4% and the SGR was 3.0%. A comparison between lettuce and chicory cultivation using BFT-AP and hydroponics revealed significant increases in shoot height, leaf count per week, and biomass of the cultivated lettuce and chicory. The SPAD values also increased significantly by 15.4-43.3%. Water quality analysis of the BFT-AP systems and crop cultivation beds showed significant differences, except for K and Na. The average NO₃^- concentration in the sediment pond was significantly higher at 45.3±1.0. Comparison of water temperature, pH, EC, DO, and ORP in the BFT-AP system and crop cultivation beds revealed similar monthly water temperatures from July to September. The pH in the catfish culture pond was 0.3-1.2 lower than that in the crop cultivation beds, and the EC was approximately 0.01- 0.03 dS/m lower in the catfish culture pond than the crop cultivation beds. The monthly average ORP in the catfish culture bed steadily increased to 479.9 mV in October. Bacillus velezensis (AFB2-2) and Chlorella fusca (CF) were applied to the biological activation bed; the population density of CF showed a continuous increase, whereas that of AFB2-2 decreased after 15 d and gradually increased thereafter. Thus, the application of the recirculating aquaponics cultivation technology with catfish (BFT) enhances catfish cultivation and promotes the growth of lettuce and chicory. Therefore, it is considered suitable for the environment-friendly cultivation of lettuce and chicory.

• Journal of Microbiology and Biotechnology
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• v.28 no.5
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• pp.718-731
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• 2018

The beneficial effects of lactic acid bacteria (LAB) have been intensively investigated in recent decades with special focus on modulation of the host intestinal microbiota. Numerous discoveries of effective probiotics are driven by a significantly increasing demand for dietary supplements. Consequently, technological advances in the large-scale production and lyophilization are needed by probiotic-related industries for producing probiotic LAB for commercial use. Our study had a dual objective, to determine the optimum growth medium composition and to investigate appropriate cryoprotective additives (CPAs) for Lactobacillus salivarius, and compare its responses with other Lactobacillus species. The one-factor-at-a-time method and central composite design were applied to determine the optimal medium composition for L. salivarius cultivation. The following composition of the medium was established (per liter): 21.64 g maltose, 85 g yeast extract, 1.21 ml Tween 80, 6 g sodium acetate, $0.2g\;MgSO_4{\cdot}7H_2O$, $0.02g\;MnSO_4{\cdot}H_2O$, $1g\;K_2HPO_4$, $1.5g\;KH_2PO_4$, $0.01g\;FeSO_4{\cdot}7H_2O$, and 1 g sodium citrate. A cryoprotective additive combination comprising 10% (w/v) skim milk and 10% (w/v) sucrose supplemented with 2.5% (w/v) sodium glutamate was selected for L. salivarius, and its effectiveness was confirmed using culture-independent methods in the freeze-dried cells of the Lactobacillus strains. In conclusion, the optimized medium enhanced the species-specific cultivation of L. salivarius. On the other hand, the cryoprotective effects of the selected CPA mixture may also be dependent on the bacterial strain. This study highlights the necessity for precise and advanced processing techniques for large-scale production of probiotics in the food and feed industries.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.6
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• pp.751-760
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• 2015

Management of renewable organic resources is important in attaining the sustainability of agricultural production. However, nutrient management with organic resources is more complex than fertilization with chemical fertilizer because the composition of the organic input or the environmental condition will influence organic matter decomposition and nutrient release. One of the most effective methods for estimating nutrient release from organic amendment is the use of N mineralization models. The present study aimed at parameterizing N mineralization models for a number of organic amendments being used as a nutrient source for crop production. Laboratory incubation experiment was conducted in aerobic condition. N mineralization was investigated for nineteen organic amendments in sandy soil and clay soil at $20^{\circ}C$, $25^{\circ}C$, and $30^{\circ}C$. N mineralization was facilitated at higher temperature condition. Negative correlation was observed between mineralized N and C:N ratio of organic amendments. N mineralization process was slower in clay soil than in sandy soil and this was mainly due to the delayed nitrification. The single and the double exponential models were used to estimate N mineralization of the organic amendments. N mineralization potential $N_p$ and mineralization rate k were estimated in different temperature and soil conditions. Estimated $N_p$ ranged from 28.8 to 228.1 and k from 0.0066 to 0.6932. The double exponential model showed better prediction of N mineralization compared with the single exponential model, particularly for organic amendments with high C:N ratio. It is expected that the model parameters estimated based on the incubation experiment could be used to design nutrient management planning in environment-friendly agriculture.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.143-148
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• 2012

Sustainable agriculture requires reliable information on the spatial distribution of the soil chemical properties for effective management of paddy fields. In order to provide adequate soil nutritional information for environmental-friendly agriculture, we investigated the soil chemical properties for 260 paddy soils sampled in Gyeongnam Province from 1999 to 2011 by four years of interval. Soil chemical properties of pH, organic matter, available phosphate and silicate, exchangeable potassium, calcium, and magnesium contents were analyzed. The pH value, organic matter, available phosphate and silicate, and exchangeable calcium and magnesium in paddy soils were significantly elevated in 2011 compared to 1999. The excessive levels of organic matter and available phosphate in paddy soils were detected in 2011. The soil available phosphate was highest in mountain foot-slope (p<0.05) and the soil organic matter was highest in diluvial terrace (p<0.05). It revealed that the soil available phosphate was the responsible factor for the differentiation of soil chemical properties by the topography in paddy soils.

• Korean Journal of Environmental Agriculture
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• v.32 no.1
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• pp.17-23
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• 2013

BACKGROUND: Today, environmentally friendly farming has become an important feature of agricultural policy. It promotes or sustains farming systems which protect and enhance the environment. This study was conducted to compare benthic invertebrate communities in an organic and a conventional paddy field in South Korea. METHODS AND RESULTS: Benthic invertebrates were collected at 11 regions of a rice paddy from June to August, 2009, 2010 and 2011. These comparisons undertaken using a community assessment approaches such as the number of individuals and species and community composition. Generally, the larger number of individuals and species of benthic invertebrates was observed in an organic paddy than in a conventional paddy field. Organic paddy fields could supported the wider range of species and abundance in aquatic invertebrates comparing to conventional paddy fields. Carrying capacity to support larger numbers of invertebrates also tends to be higher in organic paddy than in conventional paddy field. Specially, organic farming regions surrounded by forests were high quality habitat for benthic invertebrates than other surrounded regions such as grassland. CONCLUSION(S): We concluded that organic farming was more advantaged to benthic invertebrates than conventional farming. In order to improve biodiversity in rice paddy field, farming regimes without agricultural chemicals are recommended. The effect of organic management on biodiversity and abundance of benthic invertebrates could be maximized across highland farmland.

• Korean Journal of Environmental Agriculture
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• v.32 no.2
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• pp.142-147
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• 2013

BACKGROUND: This study was conducted to monitor residual pesticides in domestic agricultural products and to assess their risk to human health. METHODS AND RESULTS: 123 samples containing both general and environment-friendly certified agricultural products were purchased from traditional domestic markets and supermarkets in six provinces of Korea. Multiresidue analyses of one hundred twenty-two pesticides except for herbicides were performed with gas chromatography-electron capture detector, gas chromatography-nitrogen/phosphorus detector, and high-performance liquid chromatography. Sixteen pesticides were detected in 45 agricultural product samples, which were 38 general, 6 low pesticide and 1 of GAP agricultural product samples and the detection rate was 33.6%. Pesticides detected in agricultural product samples were cypermethrin, lufenuron, fenvalerate, bifenthrin, chlorfenapyr and iprodione. Residual concentration of 18 samples were exceeded the recommended maximum residue limit set by Ministry of Food and Drug Safety and two kinds of unregistered pesticides in korea were also detected in two samples. CONCLUSION(S): In order to do risk assessment by agricultural products consumption, estimated daily intake of residual pesticides were determined and compared to acceptable daily intake, referring to %ADI values. The range of %ADI values was from 0.038% to 2.748%. Taken together, it demonstrates the pesticides found in agricultural products samples were below the safety margin, indicating no effect on human health.

• Korean Journal of Environmental Agriculture
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• v.41 no.1
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• pp.55-64
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• 2022

BACKGROUND: This study was conducted to evaluate the residual characteristics and safety assessment of αcypermethrin and deltamethrin in minor crops, chives and spring onion cultivated in greenhouse. METHODS AND RESULTS: The insecticides α-cypermethrin 2% EC and deltamethrin 1% EC used in the experiment were diluted 1,000 times and then sprayed on chives and spring onion twice with 1-week intervals at 0, 7, 14, and 21 days before harvest. The residual insecticides were extracted from the minor crops using QuEchERS method and analyzed by GC-MS/MS. The average initial residues of α-cypermethrin and deltamethrin in chives after 21 days decreased from 2.74 to 0.82 mg/kg and 1.12 to 0.16 mg/kg, respectively. Similarly, in spring onion the residues after the same periods decreased from 0.26 to <0.01 mg/kg for α-cypermethrin and from 0.07 to <0.01 mg/kg for deltamethrin. CONCLUSION(S): The PHIs (pre-harvest intervals) for α-cypermethrin and deltamethrin in chives are recommended as 14 days before harvest with twice applications of the pesticides, whereas for α-cypermethrin in spring onion PHI of 7 days before harvest is recommended with 3 times of applications and PHI of 21 days for deltamethrin. The theoretical maximum daily intakes of cypermethrin and deltamethrin were 68.8% and 64.2%, respectively, indicating that residues of both compounds did not pose considerable health risks to consumers.

• Korean Journal of Organic Agriculture
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• v.31 no.4
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• pp.381-394
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• 2023

This study was conducted to monitor the antibiotics resistance of human-harmful bacteria isolated in the agricultural environment for hot peppers (Capsicum annuum) and tomato (Lycopersicon esculentum). As a result, we isolated 120 bacterial species (34 on fruits, 48 in soil, 21 in water, and 17 in manure), identified them with the 16S rRNA sequence, analyzed minimum inhibitory concentration (MIC) for 26 antibiotics using Sensititre ARIS Hi-Q system and then evaluated whether each bacterial genus acquired resistance for the tested antibiotics or not, according to the CLSI criteria. From difference in MIC between eco-friendly (EFM) and practical (PFM) cultivation farms, Klebsiella spp. isolated from EFM was resistant to ampicillin (AMP) and nalidixic acid (NAL), and that isolated from PFM was resistant to streptomycin (STR) and tetracycline (TET). Enterobacter spp. isolated from EFM was resistant to AMP and azithromycin (AZI), and that isolated from PFM was resistant to AMP, AZI, and STR. Meanwhile, Pseudomonas spp. isolated from EFM and PFM were all resistant to AMP, AZI, cefotaxime (FOT), cefoxitin (FOX), ceftriaxone (AXO), CHL, NAL, and STR. Staphylococcus spp. isolated from EFM and PFM were resistant to gentamycin (GEN), STR, and kanamycin (KAN), and in particular, that from EFM showed resistance for erythromycin (ERY). In conclusion, our study suggested that EFM lead STR antibiotics resistance for human-harmful bacteria to decrease, because only the bacteria isolated from hot pepper and tomato crop with PFM have showed resistance against STR antibiotics, regardless of bacterial genus.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.5
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• pp.290-303
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• 2003

Modern agriculture has been heavily dependent on chemical fertilizers to meet the food demands of ever increasing population. Progressive depletion of major plant nutrients in soil due to intensive cultivation practices has also necessitated the use of higher dose of chemical fertilizers particularly in soils where the organic matter content is very low. Indiscriminate use of chemical fertilizers and pressure on agriculturists to enhance per area crop yields has led to fast depletion of fossil fuel resources with concomitant increase in the prices of chemical fertilizers and also led to environmental pollution. Hence, the current trend throughout the world is to explore the possibility of using alternate nutrient sources or increasing the efficiency of chemical fertilizers by supplementing them with organic fertilizers and bioinoculants comprising largely microbes like, bacteria, fungi, algae etc to enhance nitrogen and phosphates in the soil thus creating a sustainable agricultural environment. Among the different microbial inoculants or biofertilizers, Azospirillum could be a potential candidate due to its non specific host root colonization. It had the capability to fix $N_2$ in wide pH regimes and even in presence of combined nitrogen. Azospirillum inoculation can increase the crop yield to 10-25% and substitute 25% of recommended doses of nitrogenous fertilizers. Apart from nitrogen fixation, Azospirillum is also involved in the root improvement, the activity which was attributed to an increase in the rate of water and mineral uptake by roots. The ability of Azospirillum to produce phytohormones was reported to enhance the root respiration rate, metabolism and root proliferation. They have also been reported to produce polyhydroxybutyrate, that can be used as a biodegradable thermosplastic. A lot of studies have addressed improvements in enhancing its efficiency to fix nitrogen fixation and hormone production.

• Korean Journal of Environmental Biology
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• v.26 no.3
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• pp.129-137
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• 2008

Alien apple snails (Pomacea canaliculata, Pomacea insularus) used in environmentally-friendly agriculture are different from indigenous snails found in Korea. Due to high herbicidal effects and cost-effectiveness, the number of farmers using the snails has been growing every year since 2000. Moreover, in 2008, because of the outbreaks of avian influenza throughout the country from March to May, 2008, central and local governments recommended the use of alien apple snails in agriculture as an alternative to the ducks-oriented environmentally-friendly agriculture. Therefore, it is expected that the use of alien apple snails in agriculture should be expanded in a near future. Since alien apple snails lay eggs with 95.8% of eclosion rate, they are considered to be potential pests unlike indigenous snails. In addition, Japan, Taiwan and most of the southeast Asian countries had already experienced severe ecological and agricultural damage by the alien apple snails. Subsequently, International Union for Conservation of Nature and Natural Resources (IUCN) designated P. canaliculata as one of "the 100 of the world's worst invasive alien species". It seems highly likely that the alien apple snails in Korea pose a potential threat to conservation of ecosystem and biodiversity since the snails were either found or invaded into the natural environments in some regions of Gangwon-Do and southern parts of Korean Peninsula. However, just recently, agricultural authorities and farmers using alien apple snails in agriculture opposed a proposition of designating the alien apple snails as an ecosystem-disturbing animal described by the Wildlife Protection Act. This is because there has been no concrete evidence of the ecological risk imposed by the alien snails up to now in Korea. Subsequently, in this paper, we analysed the ecological and agricultural risks imposed by the alien snails from the studies done in domestic and abroad. In addition, we proposed an urgent need and reasoning for ecological risk management of the alien snails at the national level as well as using the snails in agriculture.