• The Korean Journal of Pesticide Science
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• v.21 no.1
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• pp.75-83
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• 2017

The single residue analytical method was developed for determining fungicide pencycuron residues in various agricultural commodities with high-performance liquid chromatography (HPLC). Pencycuron residue was extracted with acetone from representative crops such as Korean cabbage, apple, brown rice and green pepper. After ethyl acetate/n-hexane partition and subsequent clean-up with silica gel chromatography, pencycuron residue was quantified by reversed phase HPLC with UV detection at 240 nm. The suspected residue of pencycuron was confirmed using selected-ion monitoring (SIM) LC/mass spectrometry (MS). Instrumental limit of quantitation (ILOQ) and method LOQ (MLOQ) were set at 2 ng and 0.02 mg/kg, respectively. Overall recoveries of pencycuron from different crop samples fortified at three levels (MLOQ, 10MLOQ, 100MLOQ) were 72~108%. This proposed method could be useful as official analytical method for quantification of pencycuron residues in agricultural commodities.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.5
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• pp.696-701
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• 2016

This study was conducted to evaluate the effects of heat treatment and germination on tricin and tricin 4'-O-(threo-${\beta}$-guaiacylglyceryl) ether (TTGE) formation from rice hull (Oryza sativa L.). Heat treatments were conducted at $80{\sim}140^{\circ}C$ for 1~5 h. Germination periods were 1~6 days at $37^{\circ}C$. Germinated rough rice extracts were classified as non-filtrated, filtrated, and residue after filtration. For heat treatment, the highest contents of tricin and TTGE were 253.12 and $208.39{\mu}g/g$ at $130^{\circ}C$ after 1 h, respectively. For germination, the highest contents of tricin and TTGE in rice hull were 118.20 and $95.37{\mu}g/g$ after 2 days, respectively. In the germinated rough rice extract treatment, the highest contents of tricin and TTGE were 361.76 and $308.08{\mu}g/g$, respectively, in residue after filtration of germinated rice extract for 6 days. Therefore, the optimum conditions for tricin and TTGE formation were heat treatment at $130^{\circ}C$ for 1 h, germination for 2 days, and addition of residue after filtration of germinated rough rice extract for 6 days.

• Korean Journal of Environmental Agriculture
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• v.34 no.3
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• pp.223-229
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• 2015

BACKGROUND: It is important to understand residual patterns of pesticides applied on crops for ensuring their safety in agricultural products. However, there are few studies on the residual patterns of pesticides in minor crops, which are small in cultivation area. In this study, residual amounts of bifenthrin and chlorfenapyr sprayed on perilla leaf as a minor crop were investigated to know their residual patterns. METHODS AND RESULTS: Bifenthrin and chlorfenapyr were sprayed 2 or 3 times on perilla leaves at a week interval prior to harvest, and the perilla leaves were collected at 0, 1, 3, 5 and 7 days after the final application of pesticides. Recoveries for residual analysis of pesticides spiked on perilla leaves with concentrations of 0.1 and 0.5 mg/kg were 81.9-104.8%. The residual amounts of pesticides interpreted using first order kinetics model show that dissipation constants of bifenthrin and chlorfenapyr in perilla leaves were 0.0724-0.0535 and $0.0948-0.0821day^{-1}$, respectively. In addition, the dissipation half-lives in perilla leaves were 9.6-12.9 days for bifenthrin and 7.3-8.4 days for chlorfenapyr. When pre-harvest residue limits (PHRL) of bifenthrin and chlorfenapyr at 10 days before harvest calculated on the basis of the dissipation constants and maximum residue limits of the pesticides were calculated as 17.1 for bifenthrin and 15.9 mg/kg for chlorfenapyr. CONCLUSION: Therefore, the PHRL calculated using the time-dependant residual patterns of pesticides in perilla leaves and their regression analysis may be used as experimental evidences in order to ensure the safety of pesticides in perilla leaves before harvest.

• Korean Journal of Agricultural Science
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• v.48 no.1
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• pp.33-43
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• 2021

Along with the widespread use of pesticides in the world, concerns over human health impacts are rapidly growing. There is a large body of evidence on the relationship between the exposure to pesticides and the elevated rate of chronic diseases such as different types of cancers, diabetes, neurodegenerative disorders like Parkinson, Alzheimer, and amyotrophic lateral sclerosis (ALS), birth defects, and reproductive disorders. This research assessed the health risk of pesticide residues by the dietary intake of vegetables collected from the agro-based markets of Dhaka, Bangladesh. As some of the banned pesticides were also found in vegetable samples, they may pose a higher risk because of cheaper availability and hence the government of Bangladesh should take strong measures to control these banned pesticides. Five organo phosphorus (chlorpyrifos, parathion, ethion, acephate, fenthion) and two carbamate (carbaryl and carbofuran) pesticide residues were identified in twenty four samples of two common vegetables (tomato and brinjal). The pesticide residues ranged from below a detectable limit (< 0.01) to 0.36 mg·kg^-1. Acephate, chlorpyrifos, ethion, and carbaryl were detected in only one sample, while co-occurrence occurred twice for parathion. Continuous monitoring and strict regulation should be enforced regarding the control of pesticide residues in fresh vegetables and other food commodities in Bangladesh.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.5
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• pp.531-540
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• 2016

The adoption of legume cover crops in no-tillage system can contribute to improve soil fertility by providing several benefits, including reduction in soil erosion, suppression of weed growth and N supply to subsequent crops. We conducted a field study to investigate the effect of cover crops and nitrogen fertilization rates on yield and nitrogen use efficiency of waxy corn (Zea mays L.) in no-tillage upland field. Two legume cover crops, hairy vetch (Vicia villosa Roth) and crimson clover (Trifolium incarnuturn L.) were mechanically terminated with roller in early June. For each cover crop treatment, nitrogen (N) fertilizer was applied at three different rates (145, 72.5 and $0kg\;N\;ha^{-1}$). The growth and yield characteristics of corn were significantly affected by the N fertilization rates in crimson clover plots, which suggest N mineralization from the cover crop residue was not sufficient. In contrast, N fertilization rates had no significant effect on growth and yield of corn in hairy vetch plots, indicating that the amount of N released from the cover crop is large enough to meet most of the N requirement of corn. However, the application of N fertilizer in hairy vetch cover plots resulted in slight increase of crop yield, though not statically significant, and high levels of N concentration in corn plant tissue possibly due to luxury consumption of N. Organic residues on the soil surface in hairy vetch cover plots had substantial amounts of N after harvest, ranging from 100 to $116kg\;N\;ha^{-1}$, which is presumably retained during winter season and released by microbial mineralization in subsequent year. The highest nitrogen yield efficiency was achieved in the plot with hairy vetch cover and no N fertilizer application, followed by the plot with hairy vetch cover and $72.5kg\;N\;ha^{-1}$ fertilization rate. In conclusion, hairy vetch showed better performance in corn productivity as compared with crimson clover. In addition, it was concluded that the application of N fertilizer between 0 and $72.5kg\;N\;ha^{-1}$ in combination with hairy vetch cover crop might be most efficient for corn yield under no-tillage system with climatic and soil characteristics similar to those of the experimental site.

• The Korean Journal of Pesticide Science
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• v.12 no.2
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• pp.148-154
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• 2008

This study was carried out to investigate the residue patterns of two insecticides, lambda-cyhalothrin and deltamethrin, commonly used for lettuce, under greenhouse conditions. The pesticides were sprayed with dilution of recommended and doubled doses onto lettuce. Their detection limits were $0.001\;mg{\cdot}kg^{-1}$ and mean recoveries at the fortification levels of 0.2 and $1.0\;mg{\cdot}kg^{-1}$ were from 101.17 to 104.25 and from 99.70 to 103.77%, respectively. The pesticides were gradually decreased in lettuce with time. Biological half-lives of lambda-cyhalothrin and deltamethrin were 1.7 and 1.4 days at the recommended dose and 1.8 and 1.4 days at the doubled dose, respectively. Initial residue amounts of lambda-cyhalothrin and deltamethrin at the recommended and doubled doses exceeded their MRLs. However, the residue levels of the pesticides in the crop sampled at harvest were less than their MRLs. The ratios of the estimated daily intake (EDI) to acceptable daily intake (ADI) by intake the crop harvested 10 days after spraying were less than 1% of their ADIs.

• Korean Journal of Environmental Agriculture
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• v.31 no.3
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• pp.248-254
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• 2012

BACKGROUND: In order to elucidate residual characteristics of difenoconazole and thiamethoxam by treatment to sweet persimmons for one year and to generate the data for the maximum residue limit (MRL) establishment for those pesticides in or on sweet persimmon. METHODS AND RESULTS: Systemic fungicide difenoconazole WP (10% a.i.) and systemic insecticide thiamethoxam WG (10% a.i.) were sprayed onto 12~25-years-old sweet persimmons according to its preharvest interval (PHI), respectively, and then fresh sweet persimmons were harvested at 0, 1, 3, 7, 14, 21 days after treatment from pesticide-sprayed plots at each 3 sites. The analytical methods were evaluated to limit of quantification, linearity, specificity, reproducibility and recoveries. The crop samples were extracted with acetone and performed dichloromethane partition process. The extracted samples of difenoconazole were analyzed by GC-ECD and the thiamethoxam extracted samples were analyzed by HPLC with good sensitivity and selectivity of the method. The average recoveries of difenoconazole ranged from 87.5 to 99.5% with the percentage of coefficient variation in the range 4.1~7.6% at three different spiking levels(0.02, 0.2 and 2.0 mg/kg). And the average recoveries of thiamethoxam and clothianidin ranged from 88.8 to 98.9% and 83.2 to 96.6% with the percentage of coefficient variation in the range 3.6~5.0% and 3.8~9.4% at three different spiking levels(0.02, 0.2 and 2.0 mg/kg), respectively. The residue amounts ranges of difenoconazole were 0.2~0.56 mg/kg and the residue amount was decreased below the MRL level, 1.0 mg/kg, after 1 day harvest. The residue amounts ranges of thiamethoxam were 0.08~0.28 mg/kg and the residue amount was decreased below the MRL level, 0.5 mg/kg, after 1 day harvest. And the residue amount of clothianidin was below then 0.03 mg/kg for only one test site of 14 and 28 day samples. CONCLUSION: As a result, the residual amounts of difenoconazole and thiamethoxam were not exceeded the MRL of established criteria for sweet persimmon. The biological half-lives of difenoconazole and thiamethoxam were 13.6, 19.4, 16.3 and 10.0, 15.3, 14.0 days at each three test sites, respectively.

• Journal of Climate Change Research
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• v.7 no.4
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• pp.443-450
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• 2016

The major greenhouse gases (GHGs) in agricultural sector are methane ($CH_4$), nitrous oxide ($N_2O$), carbon dioxide ($CO_2$). GHGs emissions are estimated by pertinent source category in a guideline book from Intergovernmental Panel on Climate Change (IPCC) such as methane from rice paddy, nitrous oxide from agricultural soil and crop residue burning. The methods for estimation GHGs emissions in agricultural sector are based on 1996 and 2006 IPCC guideline, 2000 and 2003 Good Practice Guidance. In general, GHG emissions were calculated by multiplying the activity data by emission factor. The total GHGs emission is $10,863Gg\;CO_2-eq$. from crop cultivation in agricultural sector in 2013. The emission is divided by the ratio of greenhouse gases that methane and nitrous oxide are 64% and 34%, respectively. Each gas emission according to the source categories is $7,000Gg\;CO_2-eq$. from rice paddy field, $3,897Gg\;CO_2-eq$. from agricultural soil, and $21Gg\;CO_2-eq$. from field burning, respectively. The GHGs emission in agricultural sector had been gradually decreased from 1990 to 2013 because of the reduction of cultivation. In order to compare with indirect emissions from agricultural soil, each emission was calculated using IPCC default factors (D) and country specific emission factors (CS). Nitrous oxide emission by CS applied in indirect emission, as nitrogen leaching and run off, was lower about 50% than that by D.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.3
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• pp.285-294
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• 1994

Dried top and root extracts of seven different weed species, fresh top and root extracts, and various concentrations of extract (0, 5, 10 and 15%, W/V) and residue rate (0.0, 0.25. 0.5, 0.75 and 1.0%) of velvetleaf (Abutilon theophrasti Medic.) were used to study their allelopathic effects on alfalfa in the laboratory and greenhouse. Top and root aqueous extracts of common lambsquarter (Chenopodium album L.), giant foxtail (Setaria faberii Herrm), redroot pig-weed (Amaranthus retroflexus L), velvetleaf, large crabgrass (Digitaria sanguinalis L), canada thistle (Cirsium arvense L.) and prostrate knotweed (Polygonium aviculare L.) significantly inhibited germination, seedling length, weight, and vigor in alfalfa. Top growth extracts of weeds exhibited greater allelopathic effects than root extracts. Alfalfa test species, WL-320, responded significantly different to the various weed species extracts in terms of allelopathic effect. The regression slopes of various top extracts showed significant variation with respect to germination percentage. Velvetleaf (b=3.69) extracts were the most inhibitory, while large crabgrass (b=2.39) extracts had the least allelopathic effect on alfalfa. When compared the activity of fresh velvetleaf extract to that of dry velvetleaf extract, dry extract was more inhibitory to alfalfa germination and seedling growth. Germination, seedling length and weight of alfalfa were inversely proportional to the concentration of dried velvetleaf extracts. Seedling emergence and survival percentage was inhibited by velvetleaf residue mixture treatment. Also, more of the toxic effects were observed from the dried top extracts, as compared to extracts from fresh top and root. These results demonstrate the allelopathic activity of different weed species extracts and suggest that weeds may affect crop growth and development due to the inhibitory effects of allelochemicals present in weed tissue.

• The Korean Journal of Pesticide Science
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• v.13 no.2
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• pp.98-104
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• 2009

This study was carried out to investigate the residue patterns of two neonicotinoid insecticides, dinotefuran and thiacloprid, commonly used for cucumber, were subjected to indicate a residual characteristic under greenhouse conditions. The pesticides were sprayed onto the crop at recommended and double doses 7 days before harvest and then sampling was done 0, 2, 3, 5, and 7 days after spraying. The amounts of their residues in the crop were analyzed with an HPLC. Their detection limits were 0.01 mg/kg for dinotefuran and 0.005 mg/kg for thiacloprid. Mean recoveries of dinotefuran and thiacloprid were from 85.78 to 89.52 and from 85.71 to 95.31%, respectively. Half-lives of dinotefuran and thiacloprid were 2.8 and 1.8 days at the recommended dose and 2.8 and 1.5 days at the doubled dose, respectively. The ratios of the EDI to ADI by intake the crop harvested 7 days after spraying were less than 0.1% of their ADIs.