• The Korean Journal of Pesticide Science
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• v.2 no.1
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• pp.59-64
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• 1998

In order to elucidate the leaching behaviour of the herbicide bentazon in soil, soil columns(5cm ID ${\times}$ 34 cm L) were packed with three different soils up to 30 cm height, followed by the treatment of [$^{14}C$]bentazon, and rice plants(Oryza sativa L.) were grown for 9 weeks on these columns, with the columns without growing rice plants as the control for comparison. The amounts of $^{14}C$ activities percolated were about 92% of the originally applied $^{14}C$ irrespective of the physicochemical properties of the soils in the absence of rice plants, whereas $21{\sim}50%$ of the originally applied $^{14}C$ was percolated in the presence of rice plants, suggesting that the amounts of $^{14}C$ leached decreased remarkably in rice-cultivating soils. Bentazon leached faster in soil with higher pH and with lower organic matter content in the presence of growing rice plants. The amounts of $^{14}CO_{2}$ evolved from the soil columns were less than 0.2% of the originally applied $^{14}C$. Smaller amounts of $^{14}C$ were translocated into shoots via roots in soils with higher organic matter content. $^{14}C$ activities distributed into the aqueous phase of the leachate collected from the soil columns increased with leaching period and by rice cultivation, whereas the physico-chemical properties of soils did not exhibit any effect. The amounts of soil-bound residues increased remarkably by cultivating rice plants.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.6
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• pp.736-743
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• 2015

Organic matter plays important roles in soil ecosystem in terms of carbon and nitrogen cycles. Due to recent concerns on climate change, carbon sequestration in agricultural land has become one of the most interesting and debating issues. It is necessary to understand behavior of soil carbon for evaluating decomposition or sequestration of organic matter and analyzing potential carbon decomposition pattern about the kinds of organic matter sources to cope with well. In order to evaluate decomposition of soil carbon according to organic material during cultivating rice in paddy field, we treated organic material such as hairy vetch, rice straw, oil cake fertilizer, and manure compost at $50{\times}50{\times}20cm$ blocks made of wood board, and analyzed carbon contents of fulvic acid and humic acid fraction, and total carbon periodically in 2013 and 2014. Soil sampling was conducted on monthly basis. Four Kinds of organic matter were mixed with soil in treatment plots on 2 weeks before transplanting of rice. The treatment of animal compost showed the highest changes of total carbon, which showed $7.9gkg^{-1}$ in May 2013 to $11.6gkg^{-1}$ in October 2014. Fulvic acid fraction which is considered to easily decompose ranged from 1 to $2gkg^{-1}$. Humic acid fraction was changed between 1 to $3gkg^{-1}$ in all treatments until organic material had been applied in 2014. From May to August in the second year, the contents of humic acid fraction increased to about $4gkg^{-1}$. The average of humic fraction carbon at treatments of animal compost was recorded highest among treatments during two years, $2.1gkg^{-1}$. The treatment of animal compost has showed the lowest ratio of fulvic acid fraction, humic acid fraction compared with other treatments. The average ratio of fulvic fraction carbon in soil ranged from 16 to 20%, and humic fraction carbon ranged from 19 to 22%. In conclusion, animal compost including wood as bulking agent is superior in sequestrating carbon at agricultural land to other kinds of raw plant residue.

• The Korean Journal of Pesticide Science
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• v.11 no.1
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• pp.27-31
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• 2007

Trifloxystrobin standard was analyzed by high performance liquid chromatography (HPLC). The recovery of the trifloxystrobin and it's metabolite CGA321113 were $84.6{\sim}95.3%$ and $86.4{\sim}87.3%$ and their detection limits for both of them were 0.04 mg $kg^{-1}$. In case of foliar application in the chinese cabbage (Brassica campestris L. ssp pekinnensis (Lour.) Rupr.), the amount of the residue of trifloxystrobin was above the maximum residue level (temporary MRL, 0.5 mg $kg^{-1}$) when it was treated either two times three to five days before harvest or three times three to seven days before harvest. Whereas in case of drenching the mount of the residue was below the temporary MRL, the residues in the cabbage in both the cases where the recommended amount (150 mL of the solution diluted 1500 times) and double of the amount were treated were 0.16 and 0.31 mg $kg^{-1}$, respectively. In conclusion, it should be safe to apply the trifloxystrobin (22% WP) in the soil of cabbage field abiding by the tentative recommendation level, but for the foliar application it appeared inappropriate.

• Korean journal of applied entomology
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• v.41 no.4
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• pp.293-298
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• 2002

Cadusafos and fosthiazate were applied at the rate of 1.8 g a.i./6$\m^2$ as pre-plant or pre-plant＋post-plant treatments on winter-grown oriental melon in a greenhouse soil infested with Meloidogyne arenaria. Nematicides reduced root-knot nematode population from 35 to 90% compared with control； fosthiazate was better than cadusafos (P ＝ 0.003) and fosthiazate pre-plant＋post-plant application reduced nematode population densities as much as 90%. Nematicides increased yield in an average of 23% (11-38%) in May, 39% (2-65%) in June, and 31% (12-46%) for the total (P ＝ 0.085). The residue in the fruit of oriental melon by post-plant treatment of fosthiazate exceeded maximum residue limit of 0.2ppm, while the Cadusafos residue was below the limit. It is concluded that fosthiazate cannot be used as a post-plant treatment in winer-grown oriental melon with overall consideration, i. e., danger of residue, value of melon, costs of nematicide, consumer demand on safer agricultural products, and effects of fallow.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.4
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• pp.340-360
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• 1982

Because of the continuing rapid increase in pesticide usage in Taiwan, much attention has been focus on pesticide contamination of food and effect of pesticides on human and environmental health. The Plant Protection Center (PPC) conducts safety evaluation of pesticides usee! in Taiwan. The pesticides are classified into different groups based on their acute toxicities. Pesticides which are classified into extremely toxic group are not allow to used on short term crops or the continuously harvest crops. The acute toxicity of pesticides to the beneficial insects are also studied, special attention has been paid to the two predators of rice brown planthopper. 60% of cultivated land in Taiwan are paddy field; therefore, acute fish toxicity was taken into consideration when a pesticide was applied for registration to be used in the paddy. Fish toxicities were evaluated by the dangerous rating value which is the amount of pesticide residue in the field water over the TLM value. Mutagenicity of pesticides was continuously evaluated by using Arne's microbial testing method. Island wide survey of residual levels of pesticides of known pollutants such as chlorinated hydrocarbon . insecticides, mercurial compounds in soil, water and biological samples were carried out constantly. The potential of a new1y Imported esticides to pollute the environment were studied by using model ecosystem. Ecological magnification (EM) of a chemical was calculated from model ecosystem. A chemical was considered as a pollutant when its EM value over 5000. In order to ensure the levels of pesticides residue of the crop within the safety limit. The 'tolerance' of pesticides on different crop groupings were established base on 1) acceptable daily intake value of individual pesticides, 2) average daily consumption of each crop groupings by Chinese person, 3) Actual residues of pesticides. on different crops obtained from supervised trials. Total about 79 pesticides for which the tolerances have been established on different crop groupings. Because the intensive agricultural system was adopted in Taiwan. The phytotoxicity of pesticides to the non-target crops was therefore become one of the important factor in the safety evaluation of pesticide usage. These will include 1) direct injury, 2) injury caused by pesticide polluted irrigation water, 3) injury caused by the pesticide polluted soil, 4) reduction of growth caused by the effect of pesticide on the soil microorganisms. This paper will reviewed all the aspects mentioned in the previous .paragraphs. Most the works have done in Taiwan by the PPC.y the PPC.

• Korean Journal of Environmental Agriculture
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• v.1 no.1
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• pp.1-13
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• 1982

Composite soil samples from 236 sites representing paddy field, up-land, orchard and plastic film house were examined for organochlorine residues by GLC-ECD. Detection frequencies and residual levels of most persistent organochlorine residues in the soil samples were found to depend on the cropping practices. Highest organochlorine residues were found in orchard soils and followed, in decreasing order, plastic film house, up-land and paddy field soils. ${\alpha}-Endosulfan$, dieldrin, p,p'-DDD and p,p'-DDT were responsible for the observed high organochlorine residues in the orchard soils. ${\alpha}-BHC$ and ${\gamma}-BHC$ were detected in all 236 soil samples. The mean residue levels of both BHC isomers were, however, remained fairly low. Residues of PCNB and ${\alpha}-endosulfan$ in native soils are reported, for the first time, in present work. PCNB was present in up-land plastic film house soils while ${\alpha}-endosulfan$ was found in all agricultural soils studied. High levels of p,p'-DDT and dieldrin were discussed in relation to crops cultivated, amount and duration of the pesticides usage. Need for continued observations on the persistent residue of pesticides in soils, already banned for general use, is emphasized.

• Korean Journal of Environmental Agriculture
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• v.16 no.4
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• pp.285-290
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• 1997

This study was conducted to develop labor-saving pesticide-fertilizer mixed formulation through a single application of mixed formulation of an insecticide imidacloprid coated on a slow release urea. The release of both total nitrogen and imidacloprid into water was delayed with increasing adhesive.Imidacloprid was released out 95% within 24 hours, whereas total nitrogen released in mixed formulation until 40 days was released less extent by increasing adhesive. There was no difference between pesticide-fertilizer mixed formulation and coated urea thereafter. The content of $NH_4-N$ in the soil treated with pesticide and urea seperating was higher until 10 days but gradually decreased compare to that of pesticide-fertilizer mixed formulation or coated urea. The population density of nitrate reducing bacteria and denitrifying bacteria in soil after treatment were lower in the pesticide-fertilizer mixed formulation and coated urea than those of pesticide and urea separate treatment. The residue of imidacloprid in soil was slightly higher in the treatment of pesticide alone than the pesticide-fertilizer mixed formulation and pesticide and urea seperating treatment. The population and control efficacy of small brown planthopper, Laodelphax striatellus, were not significance different among treatments.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.3
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• pp.207-217
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• 1995

Extracting efficiencies of seven extracting solutions currently employed in extracting heavy metals from soils were compared and the functional relationships among them were calculated by regression analysis for Cd, Zn, Cu, and Pb. Extracting solutions employed were 0.1M HCl, 0.1M $HNO_3$, 0.05M EDTA, 0.001M DTPA(pH 7.3), 1M $NH_4OAc$ (pH 7.0), 0.1M $NH_4Ox$, and 4M $HNO_3$ respectively. Soil samples were collected from rice paddy fields near old zinc mining sites and from rice paddy fields near agro-industry complexes. Soils sampled from old zinc mining sites were also extracted using a sequential extraction method. Extraction by 4M $HNO_3$ and sequential extraction were performed on the samples collected both in 1979 and in 1991 to investigate the change in content and in chemical form of heavy metals. Functional relationships among the extracting solutions were highly correlated for Cd and Zn, whereas those for Cu and Pb were not. The predominant chemical form of Cd. Zn, Cu, and Pb in soils from old zinc mining sites was found to be of sulfide/residue form. The exchangeable form of Cd, the organically bound form of Cu, and the carbonate form of Pb were relatively high, while the sulfide/residue form of Zn was very high(> 79%). Although transformation among the extracted forms was not clear during those 12 years, a decrease in total content of Cd, Zn, Cu, and Pb was clearly observed.

• The Korean Journal of Pesticide Science
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• v.12 no.4
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• pp.315-322
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• 2008

In this study, a simple, effective, and sensitive method has been developed for the quantitative residue analysis of cyhalofop-butyl and its metabolite cyhalofop acid in water and soil when kept under laboratory conditions. The content of cyholofop-butyl and cyhalofop acid in water and soil was analyzed by first purifying the compounds through liquid-liquid extraction and partitioning followed by Silica gel (adsorption) chromatography. Upon the completion of the purification step the residual levels were monitored through high-performance liquid chromatography (HPLC) using a UV absorbance detector. The recoveries of cyhalofop-butyl from three replicates spiked at two different concentrations ranged from 82.5 to 100.0% and from 66.7 to 97.9% in water and soil, respectively. The limit of detection and minimum detection level of cyhalofop-butyl in water and soil was 0.02 ppm and 10 ng, respectively. The recoveries of cyhalofop acid ranged from 80.7 to 104.8% in water and from 76.9 to 98.1 % in soil. The limit of detection of cyhalofop acid was 0.005 ppm in water and 0.01 ppm in soil, while the minimum detection level was 2 ng both in water and soil. The half-live of cyhalofop-butyl was 4.14 and 6.6 days in water and soil, respectively. The method was successfully applied to evaluate cyhalofop-butyl residues in water and soil applied aj. 30% emulsion, oil in water (EW) product.

• Toxicological Research
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• v.24 no.3
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• pp.207-212
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• 2008

Pesticide residues play several key roles as environmental and food pollutants and it is crucial to develop a method for the rapid determination of pesticide residues in environments. In this study, a simple, effective, and sensitive method has been developed for the quantitative analysis of methoxyfenozide in water and soil when kept under laboratory conditions. The content of methoxyfenozide in water and soil was analyzed by first purifying the compound through liquid-liquid extraction and partitioning followed by florisil gel filtration. Upon the completion of the purification step the residual levels were monitored through high performance liquid chromatography(HPLC) using a UV absorbance detector. The average recoveries of methoxyfenozide from three replicates spiked at two different concentrations and were ranged from 83.5% to 110.3% and from 98.1% to 102.8% in water and soil, respectively. The limits of detection(LODs) and limits of quantitation(LOQs) were 0.004 vs. 0.012 ppm and 0.008 vs. 0.024 ppm, respectively. The method was successfully applied to evaluate the behavioral fate of a 21% wettable powder(WP) methoxyfenozide throughout the course of 14 days. A first-order model was found to accurately fit the dissipation of methoxyfenozide in water with and a $DT_{50}$ value of 3.03 days was calculated from the fit. This result indicates that methoxyfenozide dissipates rapidly and does not accumulate in water.