• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.3
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• pp.43-53
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• 2023

This batch experiment evaluated the impacts of major plant nutrient releases by applying the modified Hyperbola model on the leachates and N₂O emissions from incorporated rice hull biochar with organic fertilizer materials. The treatments consisted of the control as incorporated with organic fertilizer materials, the incorporated rice hull biochar with organic fertilizer materials, and the incorporated plasma-activated rice hull biochar with organic fertilizer materials under redox conditions. The results indicated that the maximum release amount of NH₄-N was 3486.3 mg L^-1 in the control, and their reduction rates of NH₄-N, NO₃-N, PO₄-P, and K were 8.0%, 17.5% 44.3.0% and 8.7%, respectively, relative to the control. In the control, the highest soluble amount of PO₄-P was 681.0 mg L^-1. The estimations for accumulated NH₄-N, NO₃-N, PO₄-P, and K-releases in all the treatments were significantly (p<0.01) fitted with a modified Hyperbola model. For greenhouse gas emissions, the lowest cumulative N₂O was 340.4 mg kg^-1 in the soil incorporated with plasma-activated rice hull biochar, and the reduction rates were 27.8% and 86.4% in the rice hull biochar and plasma-activated rice hull biochar treatments, respectively, compared to the control. Therefore, it concluded that the incorporated rice hull biochar can be especially useful for controlling PO₄-P release and N₂O emissions for bio-fertilizer applications.

• Korean Journal of Organic Agriculture
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• v.25 no.3
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• pp.587-602
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• 2017

Correlations of soil and leaf nutrients and growth of young 'Enterprise' apple (Malus ${\times}$ domestica Borkh.) trees were analyzed with tree damage, such as Japanese beetle (JB; Popillia japonica Newman)-damaged leaves, vole damage to trunk, tree mortality, and weed density in a certified organic orchard in warm and humid environment of Southern USA. Interaction treatments of four mulch and three fertilizers were applied around trees as follows: mow-and-blow (MB), shredded paper (SP), wood chips (WC), and green compost (GC) as a mulch, with no fertilizer (NF), poultry litter (PL), and commercial organic fertilizer (CF) as a fertilizer applied in April. Vole damage to trunk and weed density were little correlated with mineral nutrients and tree growth. JB-damaged leaves were highly stimulated to 26.5% in GC-treated plots while tree mortality were increased by MB treatments. Biomass production per tree was approximately 3,700 g on the WC- and GC-treated plots, which was two times higher than those values observed on the other two mulch plots. JB-damaged leaves tended to get worse when nutrients in soil and leaf increased through the correlation analysis, with a strong positive relationship ($r^2=0.585$) observed between JB-damaged leaves and trunk cross sectional area, a vegetative indicator. Tree mortality was more negatively associated with nutrient contents and growth of trees than those of soil nutrients. Wood chips was considered for a local organic mulch materials to increase organic matter contents and to produce healthy young trees in Southern USA, with control insect, such as beetle, and vole density in an orchard habitat.

• Korean Journal of Organic Agriculture
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• v.11 no.1
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• pp.55-66
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• 2003

This study was carried out to investigate the effects of different plant growth media on the growth of tomato(Lycopersicum esculentum Mill.) seedlings during growth stages. The media were commercial plant growth medium 100％, earthworm cast (that was produced by vermicomposting of food waste and cattle manure) 100％, earthworm cast 50％ ＋ vermiculite 50％, earthworm cast 50％ ＋ perlite 50％, earthworm cast 40％ ＋ vermiculite 30％ + perlite 30％. Plant length(mm), number of leaves, leaf area($\textrm{cm}^2$), stem diameter(mm), plant dry mater were greatest till the 2nd week growth stages in the commercial plant growth medium plots, but those were higher in the earthworm cast than those in the other plant growth media at the later stages of this study(P<0.05). And relative growth rate of biological yield, relative growth rate of shoot and relative growth rate of root were highest in the earthworm cast till the 4th week growth stage. Therefore it can be implied that there is the possibility of potential utilization of earthworm cast, which was produced by vermicomposting of food waste and cattle manure, as vegetable growth medium.

• Korean Journal of Organic Agriculture
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• v.22 no.2
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• pp.269-280
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• 2014

This study was performed to test the insecticidal and antimicrobial activity of plant extracts from clove, Sophora flavescens Aiton and neem. As the result of antimicrobial activity test, clove extract showed the strongest activity against Botrytis cinerea. In insecticidal activity test, the extract of Sophora flavescens Aiton was the highest against Nilaparvata lugens. The pyroligneous liquor (10%) and emulsified spreader (10%) were added to the extracts of clove and Sophora, respectively, to apply the environment-friendly rice field. In the field treated clove extract, disease damage occurred 49.1% and insect damage occurred 29.5% compared to control plot (100%). In the field treated Sophora extract, disease damage was 56.7% and insect damage was 21.0% compared to control plot (100%). In conclusion, plant extracts from Sophora and clove could control about 50% of disease and about 70% of insect damage that they could be used as environment-friendly resources to control disease and insect in rice farming.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.376-382
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• 2014

The soluble loess-sulfur mixture allowed standing to remove insoluble component materials for five weeks after manufacturing. We decreased the pH level of soluble loess-sulfur mixture at pH 1.0 modified with decreasing 25% sodium hydroxide than original content. The pH ranges of soluble loess-sulfur mixture solutions were adjusted to pH 5.0-pH 11.0 (pH 1 unit) with brown rice vinegar (pH 2.8). The pH of original loess-sulfur mixture was about pH 13 and damaged the foliar parts and young leaves of tomato after twice application. These stock solutions can be diluted 500:1 with tap water to make a 0.05% working solution and were sprayed two times with 7 days interval to the leaf and stem of tomato, which were spontaneously infected with E. cichoracearum. Control efficacy of powdery mildew ranged from 85% to 90% at 7 days after first application. After second application, each loess-sulfur mixture solutions adjusted pH level significantly suppressed the powdery mildew disease in tomato. Consequently, loess-sulfur complex adjusted pH level with brown rice vinegar was suggested to be low in acute toxicity at all different pH values and suggested to use an agent for control of tomato powdery mildew in organic farming.

• The Korean Journal of Mycology
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• v.52 no.1
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• pp.61-71
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• 2024

Next-generation sequencing of shiitake, oyster, and king oyster spent mushroom substrates collected from Chun-cheon, Yeo-ju, Hong-cheon, Gwang-ju, Ui-ryeong, and A-san was performed. Metabarcoding analysis using amplicon sequence variants was performed to confirm the microbial content ratio in the medium after harvesting the collected mushrooms; the ratio of the contents of various microorganisms in the medium after mushroom harvest varied depending on the materials added to produce the mushroom medium. The WPGMA analysis of the similarity between microbial communities, which was based on the β-diversity, confirmed that the microbial communities in the substrates of the different mushroom varieties were similar.

• The Korean Journal of Pesticide Science
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• v.17 no.4
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• pp.473-477
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• 2013

This study was performed to evaluate the acute contact and oral toxicity of plant extracts (neem, sophora and derris) against Honeybee (Apis mellifera L.). As a result of acute contact toxicity test, $LD_{50}$ of neem and derris extracts were more than 100 ${\mu}g/bee$ while $LD_{50}$ of sophora extracts were 1.7 ${\mu}g/bee$. In case of acute oral toxicity test, $LD_{50}$ of neem and derris extracts were more than 100 ${\mu}g/bee$ while $LD_{50}$ of sophora extracts were 1.7 and 0.3 ${\mu}g/bee$. In conclusion, it is evaluated that neem and derris extracts are practically nontoxic while sophora extracts are highly toxic.

• Korean Journal of Organic Agriculture
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• v.24 no.4
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• pp.945-955
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• 2016

To date, chemical managements of plant bacterial diseases are complicated by limitations on use of antibiotics in agriculture, antibiotic resistance development, and limited efficacy of alternative control agents. In this study, thus, we performed screening of eco-friendly farming material (notice no. 2-4-064) containing tannic acid as new antibacterial-activity against 7 plant bacterial pathogens: Pectobacterium carotovorum subsp. carotovorum (Pcc), Ralstonia solanacearum (Rs), Acidovorax avenae subsp. citrulli (Aac), Xanthomonas cirti pv. citri (Xcc), Erwinia pyrifoliae (Ep), Clavibacter michiganensis subsp. michiganensis (Cmm), and Streptomyces scabies (Sc), Initial screening of antibacterial effects of eco-friendly farming material was performed using the paper disk diffusion method and co-cultivation in broth culture. Tannic acid based eco-friendly farming material showed inhibitory effect against Pcc, Rs, Aac, Xcc, Cmm, and Ss, whereas it did not show inhibition zone against Ep. However, when it tested by co-cultivation in broth culture, it showed strong inhibition effect against all pathogens that declined growth curve compared to bacterial pathogen only. Interestingly, when we observed morphological changes on those pathogens by SEM, cell morphologies of 7 pathogens were slightly changed that seem to be malfunction in their cell envelope.

• Korean Journal of Environmental Agriculture
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• v.33 no.2
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• pp.138-143
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• 2014

BACKGROUND: Azadirachta Indica extract(AIE) and Sophorae radix extract(SRE) are widely used as environment-friendly organic materials of plant origin in South Korea. METHODS AND RESULTS: In this study, the in vitro micronucleus(vitMN) tests of two samples of AIE and SRE were conducted to evaluate their genotoxicity using the Chinese hamster lung(CHL) cell. This study was composed of two parts; cytochalasin B(cyto B) test and non-cyto B test. Mitomycin C and colchicine were used as positive controls. As a result, the incidence of micronucleus(MN) in all AIE and SRE treated groups increased in dose-dependent manner, but were less than 2.2% in 1,000 binucleated cells. In addition, there were no significant increases of MN incidence in all AIE and SRE treated groups, compared with the negative control group. CONCLUSION: Therefore, we suggest that AIE samples and SRE samples used in this study may have no genotoxicity in the in vitro micronucleus test using the CHL cells. In our previous study, we reported that AIE and SRE did not cause genotoxicity in Ames test. According to the genotoxicity battery system, we concluded that AIE and SRE used in this study have no genotoxic effects to humans.

• Korean Journal of Organic Agriculture
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• v.25 no.3
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• pp.619-630
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• 2017

In recent years, not only the cultivation area of Jujube in Korea but also the number of pest species has increased. The farmers farming environmentally friendly are in great difficulty because there are no effective control devices. This study was conducted to investigate the control effect of the insect screen net on three pest species (Apolygus spinolae, Dasineura sp. and Carposina sasakii) in Jujube orchard when the pests were blocked by insect screen net. For the first and second surveys, the damage rates by A. spinolae were 9.06, 13.95% in 50 mesh, 4.75, 10.17% in 25 mesh, 5.68, 11.84% in 18mesh mesh of insect screen net and 21.6, 36.34% in untreated insect screen net, respectively. The damage rates by Dasineura sp. were 0.54, 0.13% in 50 mesh, 0.93, 2.84% in 25 mesh, 1.05, 13.45% in 18 mesh mesh of insect screen net and 11.1, 26.65% in untreated insect screen net. Carposina sasakii were completely blocked in all the treatments. Damages on Jujube were not observed by insect screen net. Therefore, insect screen net is effective on insect pest control for Jujube.