• Korean Journal of Environmental Agriculture
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• v.29 no.2
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• pp.109-114
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• 2010

Rape residue as green manure is an emerging alternative of chemical fertilizer to improve soil quality and crop productivity. Objective of this research was to evaluate the effectiveness of rape residue as green manure on reduction of chemical fertilizer and suppression of weed occurrence in rice-rape double cropping system. Greenhouse experiment was conducted with four treatments: the combination of rape residue and three different N application rates (0, 30 and 70% of recommended application rate (7.8 kg N $10a^{-1}$)) and 100% chemical fertilizer as a control. No difference in rice clum length was observed for all treatments, while panicle length was highest in a treatment of rape residue+70% chemical fertilizer (Rape+70%CF). In addition, rice grain weight at a Rape+70%CF treatment increased by 19% compared to the control. This treatment also reduced weed density and biomass by 58 and 53%, respectively, compared to the control. Our results suggest that use of rape residues as green manure is an environment friendly and effective way to reduce chemical fertilizer and to enhance crop productivity in rice-rape double cropping system in Korea.

• Korean Journal of Environmental Agriculture
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• v.36 no.1
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• pp.22-28
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• 2017

BACKGROUND: There is very limited knowledge of the effects of biochar derived from exhausted coffee residue on metal adsorption processes. Furthermore, only limited information is available on the adsorption mechanism of copper. The aim of this study was to evaluate the absorption behaviors of copper by biochar derived from exhausted coffee residue. METHODS AND RESULTS: Biochars produced by pyrolysis of exhausted coffee residue at $300^{\circ}C$(CB300) and $600^{\circ}C$(CB600) were characterized and investigated as adsorbents for the removal of copper from aqueous solution. The results indicated that the adsorption equilibrium was achieved around 2 h and the pseudo-second-order kinetic model fit the data better than the pseudo-first-order kinetic model. The maximum Cu adsorption capacities of CB600 by Freundlich and Langmuir isotherms were higher than those of CB300. The adsorption data were well described by a Langmuir isotherm compare to Freundlich isotherm. CONCLUSION: Our results suggest that exhausted coffee residue can be used as feedstock materials to produce high quality biochar, which could be used as adsorbents to removal copper.

• Korean Journal of Environmental Agriculture
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• v.14 no.1
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• pp.28-44
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• 1995

Residue level of myclobutanil[2-p-chlorophenyl-2-(1H-1,2,4-trizol-l-yl-methyl) hexane nitril] and number of soil microorganism were investigated at different environmental conditions such as the sterile and the non-sterile soils, moisture content, pH, temperature, application rate, and soil types under laboratory and field to study the effect of those factors on degradation characteristics of this fungicide and change of microflora in soil. Decomposition rate of myclobutanil was 3.9 times faster in the non-sterile soil than in the sterile soil, 1.6 times in the field than in the laboratory, 1.4 times in the concentration of 10ppm than in that of 20ppm, and 1.2 times in the clay loam soil than in the silty loam soil. Degradation rate of myclobutanil was the fastest at pH 9.0 among the tested pHs and the latest at pH 5.5. Degradation rate of myclobutanil was in order of $27^{\circ}C$ > $37^{\circ}C$ > $17^{\circ}C$. Otherwise, the effect of soil water content on myclobutanil degradation was found not clear. Number of microorganism in the non-sterile soil was remarkedly more than that in the sterile soil. Numbers of microbes were not significantly different between treatment plot and non-treatment plot of myclobutanil at the different conditions of soil moisture content, pH, temperature and soil type. Numbers of fungi and total microbes were more in the treatment than in the non-treatment of myclobutanil at field test but the same trends were not found at laboratory test. Within non-treatment of myclobutanil, numbers of microbes were not significantly different under the various condition of pH, application rate, and soil type in laboratory and upland field. The number of bacteria were more in 60% moisture content of water holding capacity than in 40% and the number of fungi were more in $17^{\circ}C$ of soil temperature than in $37^{\circ}C$. Within the application plot of myclobutanil, numbers of microbes were not significantly different at various pH in laboratory and upland field. The number of bacteria and total microbes were more in 80% moisture content of water holding capacity than in 40% and 60% and actinomycetes were more at $27^{\circ}C$ in the clay loam soil than at $17^{\circ}C$ in the silty loam soil.

• The Korean Journal of Pesticide Science
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• v.17 no.4
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• pp.283-292
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• 2013

A series of monitoring studies were carried out to evaluate the residue level of pesticides in different native soils from 1999 to 2006. The nation-wide collection of soil samples from paddy, greenhouse, upland and orchard, were analyzed by GLC (ECD or NPD) and GC/MS. The results obtained are summarized as follows; out of 14 pesticides detected from paddy soils in 1999, the highest residue level was 0.25 mg $kg^{-1}$, and the frequency was 21.7% as butachlor, 20.0% as isoprothiolane, and 16.7% as iprobenfos. In 2003, 7 pesticides were detected and their frequencies were 0~36.0%; the frequency was 36.0% as isoprothiolane and 33.3% as oxadiazon. In the year 2000, 57 pesticides in the greenhouse soil samples were detected with the highest frequency of 65.3%. Of the pesticides detected, endosulfan and procymidone showed the frequency of 65.3 and 50.0%, respectively. In 2004, 19 pesticides were detected from greenhouse soils, and their frequencies and residue levels were decreased. Endosulfan and procymidone showed high detection frequencies and concentrations of 21.3 and 9.3% and 0.76 and 0.31 mg $kg^{-1}$, respectively. In 2001, a total of 25 pesticides were detected through monitoring in 170 upland soils and the highest residue level was 2.24 mg $kg^{-1}$. The detection frequencies showed the range of 0~53.5%. Especially, endosulfan showed the highest frequency of 53.5%. Residue levels and frequencies of pesticide in the year 2005 were almost the same compared with that of the year 2001. As a result of monitoring in 150 orchard soils in 2002, 26 pesticides were detected and the highest residue level was 1.43 mg $kg^{-1}$. Of them, the frequency of endosulfan showed the highest as 45.3%. In 2006, 20 pesticides were detected in orchard soils. The frequency of total endosulfan was the highest as 5.3% but was lower than that of the year 2002.

• Journal of Applied Biological Chemistry
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• v.60 no.4
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• pp.343-349
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• 2017

This study was conducted to investigate the residual level and the amount of transfer to lettuce grown in field condition treated with the 5-methyl-1,2,4-triazolo[3,4-b][1,3]benzothiazole (Azoxystrobin). The field trials on lettuce were carried out at two different green houses located in Gwangju (Field 1) and Yongin (Field 2). Soil and lettuce samples were collected at different days after soil treatment of azoxystrobin with two different concentrations, respectively. Average recoveries for azoxystrobin ranged from 86.9 to 113.6% from soil and lettuce with the variation coefficient of 0.1-4.6%. The initial concentrations of azoxystrobin in Gwangju soil were 9.20, 11.00 mg/kg and decreased to 1.36, 2.70 mg/kg at 43 DAT (days after treatment) in field 1, while 1.06, 2.23 mg/kg decreased to 0.20 and 0.67 mg/kg at 36 DAT in field 2, respectively. The half-lives of azoxystrobin were about 19.4 and 23.3 days for the low and high concentration of azoxystrobin treated soils in field 1 and 11.5 and 17.8 days in field 2 soils, respectively. Residue levels of azoxystrobin in lettuce were not detected in filed 1 and field 2 soils, respectively.

• The Korean Journal of Pesticide Science
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• v.19 no.1
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• pp.14-21
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• 2015

To determine residual characteristics of azoxystrobin in ginseng under different cultivation conditions such as use of straw mat on cultivation soil and filling gap between ginseng stem and soil surface and also to elucidate its approximate behavior after spraying, 20% azoxystrobin suspension concentrate solution was sprayed 4 times onto 5-year-old ginseng with 10 days interval at a application rate of about 200 L/10 a and then residues in samples were analyzed. The residue level was lower in case of use of straw mat and filling the gap with soil than in case of no use of straw mat and no filling the gap, representing that use of straw mat and filling the gap with soil were contributed to decrease of pesticide residues in ginseng. A large portion of the test pesticide distributed onto ginseng leaf with a higher specific surface area. The amounts of azoxystrobin residues decreased in ginseng leaf, while increased on soil surface, as close to harvest. About 0.1% of azoxystrobin sprayed was distributed in ginseng root and 12.7-20.4% (mean 16.6%) of azoxystrobin could be decreased for dietary intake by removing of rhizome from ginseng root before intake.

• Applied Biological Chemistry
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• v.31 no.1
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• pp.79-85
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• 1988

The effects of herbicides on biochemical processes in soil environment were studied by examining the effects of the chemical structure of each herbicides on soil enzyme activities and pesticides residue revealed when soil treated with urea was incubated at $28{\pm}1^{\circ}C$ for 56 days. The inhibition effects of herbicides on soil enzyme activites in soil decreased in the order of urea group>dinoseb>propanil>diphenyl eter group>acid amide group for urease, and dinoseb>urea group>diphenyl ether group>acid amide group for L-glutaminase and protease, dinoseb>diphenyl ether group>urea group>acid amide group for phosphatase. Herbicides inhibited the activities of soil enzyme in the early stage of treatment but increased the activities of urease, L-glutaminase and protease in the late stage. When herbicides were treated in soil together with urea the degradation of insecticides was accelerated.

• The Plant Pathology Journal
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• v.32 no.4
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• pp.329-339
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• 2016

The short-term effects of low-level contamination by heavy metals (As, Cd, Cu, and Pb) on the soil health were examined by analyzing soil nematode community in soils planted with tomatoes. For this, the soils were irrigated with five metal concentrations ([1, 1/4, $1/4^2$, $1/4^3$, and 0] ${\times}$ maximum concentrations [MC] detected in irrigation waters near abandoned mine sites) for 18 weeks. Heavy metal concentrations were significantly increased in soils irrigated with MC of heavy metals, among which As and Cu exceeded the maximum heavy metal residue contents of soil approved in Korea. In no heavy metal treatment controls, nematode abundances for all trophic groups (except omnivorous-predatory nematodes [OP]) and colonizer-persister (cp) values (except cp-4-5) were significantly increased, and all maturity indices (except maturity index [MI] of plant-parasitic nematodes) and structure index (SI) were significantly decreased, suggesting the soil environments might have been disturbed during 18 weeks of tomato growth. There were no concentration-dependent significant decreases in richness, abundance, or MI for most heavy metals; however, their significant decreases occurred in abundance and richness of OP and cp-4, MI2-5 (excluding cp-1) and SI, indicating disturbed soil ecosystems, at the higher concentrations (MC and MC/4) of Pb that had the most significant negative correlation coefficients for heavy metal concentrations and nematode community among the heavy metals. Therefore, the short-term effects of low-level heavy metal contamination on soil health can be analyzed by nematode community structures before the appearance of plant damages caused by the abiotic agents, heavy metals.

• Journal of Biosystems Engineering
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• v.41 no.4
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• pp.304-312
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• 2016

Purpose: Soil strength has been measured using a cone penetrometer, which is making it difficult to obtain the spatial data required for precision agriculture. Our objectives were to evaluate real-time horizontal soil strength (RHSS) to measure soil strength in real time while moving across the field. Using the RHSS data, the tillage depth was determined, and the power consumption of a tractor and rotavators were compared. Methods: The horizontal soil-strength index (HSSI) obtained by the RHSS was compared with the cone index (CI), which was measured using a cone penetrometer. Comparison analysis in accordance with the measurement depth that increased at 5-cm interval was conducted using kriged maps at six sensing depths. For tillage control and evaluation of the power consumption, the system was installed with a potentiometer for tillage depth, a torque sensor from the rear axle, and a power take-off (PTO) shaft. Results: The HSSI was lower than the CI, but they were the same at 54.81% of the total grids for the 5-cm depth and at 3.85% for the 10-cm depth. In accordance with the recommended tillage map, tillage operations between 0 and 15 cm left 2.3% and 7% residue cover on the soil, and that between 20 and 10 cm covered a wider utilization of 3% and 18.4%, respectively. When the tillage depth was 15 cm, the comparison result of the power requirements between the PTO and rear axle in terms of control performance revealed that the maximum power requirements of the axle and PTO were 44.63 and 23.24 kW, respectively. Conclusions: An HSSI measurement system was evaluated by comparison with the conventional soil strength measurement system (CI) and applied to a tractor to compare the tillage power consumption. Further study is needed on its application to various farm works using a tractor for precision agriculture.

• Korean Journal of Environmental Agriculture
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• v.20 no.5
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• pp.305-309
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• 2001

Thirty-day-old rice seedlings, IR-20 variety were transplanted into the experimental plots and were sprayed with endosulfan (35% EC) after 52 days at the rate of 0.64 kg a.i/ha. Residues of endosulfan in the plant, soil, and water were found to decrease steadily upto 15 days. A second application of the pesticide was made on the 31st day and the plant was harvested on 56th day after the first application. The residue level on hay and grains was 0.7 ${\mu}g/g$. This level is seven times higher than FAO/WHO-prescribed tolerance level of 0.1 ${\mu}g/g$. Metabolites of endosulfan were traced out in plants, soil, and water during the pre- and post-harvest period.