• Korean Journal of Environmental Agriculture
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• v.31 no.2
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• pp.137-145
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• 2012

BACKGROUND: Along with the surplus rice production, introduction of upland crop cultivations into newly reclaimed tidal areas has gained public attentions in terms of farming diversification and farmers income increase. However, its impacts on the surroundings have not been well studied yet, especially associated with nutrient balance from reclaimed upland cultivation. The objective of this study was to investigate water and nutrient balance during winter barley cultivation as affected different fertilization methods. METHODS AND RESULTS: TN and TP balance for three different plots treated by livestock compost, chemical fertilizer, and no application were monitored during winter green barley cultivation (2010-2011) at the NICS Kyehwa experimental field in Jeonbuk, Korea. Nutrient content in soil and pore water near soil surface appeared to increase, while sub-soil layer remained similar with no fertilization plot. Livestock compost application appeared to increase organic matter content in surface soil compared to chemical fertilization. Crop yield was the greatest with livestock compost application (10.6 t/ha) followed by chemical fertilization (6.9 t/ha) and no application (1.8 t/ha). The nitrogen uptake rate was also greater with livestock compost (52.4%) than chemical fertilizer (48.1%). Phosphorus uptake rate was much smaller (about 7.0%) compared to nitrogen. Nutrient loss by surface and subsurface runoff seemed to be minimal primarily due to small rainfall amount during the winter season. Most of the remaining nutrients, particularly phosphate seemed to be stored in soil layer. Phosphate accumulation appeared to be more phenomenal in the plot applied by livestock compost with higher phosphorus content. CONCLUSION: This study demonstrated that livestock compost application to tidal upland may increase barley crop production and also improve soil fertility by supplying organic content. However, excessive phosphorus supply with livestock compost seems likely to cause a phosphate accumulation problem, unless the nitrogen-based fertilization practice is adjusted.

• Korean Journal of Environmental Agriculture
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• v.29 no.4
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• pp.336-342
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• 2010

In a pot experiment, we studied the effect of nitrification inhibition on Fe reduction and P release in paddy soil and growth and nutrient uptake of rice plant. Recommended level of fertilizers, 6 kg N, 5 kg $P_2O_5$ and 4 kg $K_2O$ per 10a, were applied, and for N fertilizer urea, urea+N-serve, and $KNO_3$ were included. Four 30-day-old seedlings were transplanted in a waterlogged 9 L pot filled with Yuga series soil, and 3 pots were prepared in each N fertilizer treatment. Changes of soil redox potential and concentration of ${NH_4}^-$, ${NO_3}^-$, $Fe^{2+}$ and ${PO_4}^{3-}$ in soil solution at 10 cm depth were monitored, and also the growth and nutrient uptake of rice plants were measured. Concentration of ${NH_4}^+$ in soil solution was highest in urea+N-serve treatment, and followed by urea and $KNO_3$ treatments. Addition of N-serve could effectively inhibit nitrification in the soil. In the treatment of $KNO_3$, relatively higher ${NO_3}^-$ concentration was found at 10 cm depth soil. In urea+N-serve treatment redox potential was lower than -100 mV during the experiment, but in the treatment of $KNO_3$ the potential was maintained above 0 mV until ${NO_3}^-$ remaining in soil solution. Reduction of Fe(III) and solubilization of P were highly correlated with redox potential changes in the three N fertilizer treatments. Concentrations of Fe(II) and ${PO_4}^{3-}$ in soil solution at 10 cm depth were much higher in the urea+N-serve treatment. The most vigorous rice seedling growth was found in the urea treatment. Although the availability of N and P in soil was enhanced in the urea+N-serve treatment through the suppression of nitrification, excessive solubilization of Fe could limit the growth of rice plants.

• Korean Journal of Environmental Agriculture
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• v.36 no.4
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• pp.230-240
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• 2017

BACKGROUND: To evaluate residues of environmentally concerned pesticides in water system, this monitoring was conducted over three rivers. The residual characteristics and discharging condition of these residues on water system was investigated. METHODS AND RESULTS: Total twenty nine sampling sites were selected through main streams and branch streams of Keum, Mangyung and Dongjin rivers, and the water samples from them were regularly collected one month interval, especially biweekly from May to August in 2002. Of the pesticides monitored, six fungicides which include hexaconazole, isoprothiolane and iprobenfos were detected with frequencies of 0.3-50.9% and in their residue level of $0.1-4.7{\mu}g/L$. Sixteen insecticides which include nine organophosphoruses, three carbamates, endosulfan, cypermethrin, buprofezin and fipronil were detected with frequencies of 0.3-32.5% and in their residue level of $0.01-2.8{\mu}g/L$. Nine herbicides which include alachlor molinate, anilofos, butachlor, dimepiperate, metolachlor, oxadiazon, pretilachlor and thiobencarb were detected with frequencies of 0.8-22.9% and in their residue level of $0.01-9.07{\mu}g/L$. CONCLUSION: Detection frequencies and residue levels of insecticides and herbicides were the highest in waters sampled in May and June. Almost pesticides detected were for the paddy rice and their residue levels were very low to compare with standard values.

• Korean Journal of Environmental Agriculture
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• v.36 no.4
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• pp.279-287
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• 2017

BACKGROUND: Many farmers who cultivate the strawberries for export have used agricultural chemicals which MRL (Maximum Residue Limits) of main export target countries or simultaneous multi-residue analysis in Korea have not been established. Among them, the cyenopyrafen and cyflumetofen were selected and applied to this study to determine the PHI (pre-harvest interval) which is appropriate to the PLS (Positive List System) criterion (0.01 mg/kg) and to investigate the residual amounts in the samples. In addition, Fifty pesticides were monitored to check up whether it is suitable or not for main export target countries. METHODS AND RESULTS: Cyenopyrafen and cyflumetofen were spayed out to the strawberries. Samples for residual analyses were taken for maximum 60 days. After sampling, they were extracted by the QuEChERS method and analyzed using the LC-MS/MS. Cyenopyrafen and cyflumetofen were detected in a range of 0.0106~2.6517 mg/kg and of 0.0005~1.4480 mg/kg, respectively. From this results, they were found to be suitable for PLS concentration after 30 or 45 days after spray. In addition, they were detected in most samples that were selected at random. Their concentrations were higher than the PLS criterion in the maximum twenty samples. Twelve of pesticides unsuitable for main export target countries have been detected in the monitoring of simultaneous multi-residue analysis. The result indicates they are unsuitable for export since they excesses over PLS criterion. CONCLUSION: The monitoring result showed it is necessary to establish the pesticide standards of safe use suitable for the PLS criterion. In addition, it is considered continues management and inspection are needed to solve problems caused by unsuitable pesticides in export strawberries.

• Journal of Food Hygiene and Safety
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• v.30 no.2
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• pp.143-149
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• 2015

This study was conducted to simultaneous analysis methods for water soluble vitamins B group (vitamin $B_1$, vitamin $B_2$, nicotinic acid, nicotinamide, vitamin $B_6$) which is used as health functional foods etc. Analytical methods of water-soluble vitamins B group by HPLC were established through instrumental analytical conditions, and the examination of data such as domestic and foreign reliable methods, and papers of journal. HPLC method analyzing water soluble vitamins B group was established using Capcell Pak C18 UG 120 column in 270 nm through test of columns. The validation has been performed on the method to determine linearity, accuracy, limits of quantification (LOQ) and repeatability for water soluble vitamins B group. An excellent linearity ($r^2=0.999$) was observed for vitamin $B_1$, vitamin $B_2$, nicotinic acid, nicotinamide, vitamin $B_6$ in the concentration range ($0.1{\sim}2{\mu}g/mL$). Observed recovery of vitamin $B_1$ was found to be between 100 and 103%, vitamin $B^2$ was found to be between 104 and 112%, nicotinic acid was found to be between 82 and 85%, nicotinamide was found to be between 121 and 124% and vitamin $B_6$ was found to be between 95 and 104%. LOQ of vitamin $B_1$ was found to be $0.04{\mu}g/mL$, vitamin $B_2$ was found to be $0.05{\mu}g/mL$, nicotinic acid was found to be $0.15{\mu}g/mL$, nicotinamide was found to be $0.08{\mu}g/mL$ and vitamin $B_6$ was found to be $0.63{\mu}g/mL$. Repeatability precision for vitamin $B_1$ was found to be 0.4%, vitamin $B_2$ was found to be 0.4%, nicotinic acid was found to be 0.5%, nicotinamide was found to be 0.7% and vitamin $B_6$ was found to be 0.4% relative standard deviation (RSD). Also, verify the accuracy of the simultaneous analysis methods, we monitored the labeled contents of the health functional foods and children's preferred foods.

• Journal of Food Hygiene and Safety
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• v.25 no.1
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• pp.36-42
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• 2010

The method for the determination of ethylenediamine (EDA) and hexamethylenediamine (HMDA) in food simulants was developed, and migration amounts of these compounds was monitored for 124 polyamide (PA) utensils. The diurethane derivatives of EDA and HMDA, which produced by reaction with ethyl chloroformate, were analyzed by using gas chromatograph (GC)/flame ionization detector (FID) and GC/mass spectrometer (MS). The developed method was validated with $0.3\;{\mu}g/mL$ of limit of detection (LOD) for EDA and $0.1\;{\mu}g/mL$ of LOD for HMDA, > 0.999 of linearity($r^2$) and > 88% of recovery. The EDA was detected 1.31 and $02.06\;{\mu}g/mL$ for 2 samples in water. The HMDA was detected $0.29\;-\;0.93\;{\mu}g/mL$ for 3 samples in 20% ethanol and $0.26\;-\;0.44\;{\mu}g/mL$ for 10 samples in n-heptane. These migration levels were below the specific migration limits (SML) of $12\;{\mu}g/mL$ and $2.4\;{\mu}g/mL$ for EDA and HMDA established in EU.

• Journal of Food Hygiene and Safety
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• v.32 no.5
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• pp.348-354
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• 2017

Internationally different food safety regulation and standards could cause troubles in trade unless those are built on scientific knowledge. In this research, we monitored the microbial population and analyzed the results to determine the level of microbial contamination in foodstuffs using relatively new statistical analysis (microbiological sampling plan, International Commission on Microbiological Specification for Foods). The goal of this research falls on establishing entirely new standards for various food categories addressed in the Korean "Food Code". Targets for monitoring were indicator organisms (i.e. total aerobic count, coliform and Escherichia coli) and foodborne pathogens (i.e. Bacillus cereus, Staphylococcus aureus and Clostridium perfringens) in ready-to-eat (RTE) products. As the result of the monitoring, total aerobic count, coliform, E. coli, and B. cereus in RTE products were found at the mean values of 2.10 log CFU/g, -0.60 log CFU/g, -1.33 log CFU/g and -1.23 log CFU/g, respectively. S. aureus was detected with the level of -1.35 log CFU/g only in fresh-cut food, while C. perfringens was -1.37 log CFU/g only in ready-to-cook food. Other samples did not have any food borne pathogens. Total aerobic count, B. cereus, S. aureus and C. perfringens satisfied the Food Code (the MFDS). On the basis of the analysis, we proposed a draft of microbial criteria for RTE products.

• The Journal of the Korean Society for Microbiology
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• v.21 no.4
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• pp.487-501
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• 1986

Previous studies from our laboratory suggested that Korean LJP patients might habor A. actinomycetemcomitans of different serotype from Caucasian LJP patients in whom serotype b was predominant. In order to observe the prevalence and serotype distribution of A. actinomycetemcomitans in localized juvenile periodontitis patients and to evaluate leukotoxic activity of oral isolates, this study was performed. A. actinomycetemcomitans was isolated by using a selective medium(tryptic soy agar supplemented with 10% serum, $75{\mu}g$ of bacitracin and $5{\mu}g$ of vancomycin per ml). Using immunoabsorbed, ammonium sulfate-fractionated serotype-specific antisera, a total of 69 strains were serologically categorized by ELISA. Leukotoxicity was monitored biochemically by measuring lactate dehydrogenase indicator of cell viability in culture supernatant of PMNL plus viable A. actinomycetemcomitans mixture. The results were as follows: 1. A. actinomycetemcomitans was detected in 75% of 16 LJP patients, and 71% in the LJP lesions and 6% in the control sites. 2. Presence or absence of A. actinomycetemcomitans in the sampled disease sites has no in fluence on clinical measurements. 3. Three serotypes were approximately equally distributed in overall 9 patients. Three patients harbored 2 different serotypes of A. actinomycetemcomitans in the same disease site or different disease sites. 4. The proportion of leukotoxic oral isolates was 22% of a total of 46 strains and the prevalence was 69% in 13 sampled sites. The same disease site could harbor both leukotoxic and nonleukotoxic strains. 5. Distribution of leukotoxic strains in 3 serotypes were not different.

• Horticultural Science & Technology
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• v.32 no.3
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• pp.400-407
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• 2014

Urban farming supplies emotional stability and fresh vegetables to participating persons, however, no information regarding the biosafety of agricultural products from urban farming is available. Here, we collected 260 samples of Chinese cabbages and lettuce from 4 urban community gardens and 6 roof gardens in Seoul from September through October 2012, and monitored the microbiological and parasitological contamination quantitatively and/or qualitatively. The mean counts of total aerobic bacteria and coliforms were $6.1{\pm}0.8\;log\;CFU{\cdot}g^{-1}$ ( range, $5.4{\pm}0.6{\sim}7.1{\pm}0.8\;log\;CFU{\cdot}g^{-1}$) and $4.0{\pm}0.7\;log\;CFU{\cdot}g^{-1}$ (range, $2.3{\pm}0.6{\sim}6.1{\pm}0.9\;log\;CFU{\cdot}g^{-1}$), respectively. Coliforms were detected on 59.6% among 260 vegetable samples. There were no significant differences in the contamination levels of total aerobic bacteria and coliforms between the Chinese cabbages and lettuce, whereas both levels of vegetables from urban community gardens were higher than those of roof gardens (p > 0.05). Escherichia coli was isolated at 3.1% among whole vegetables, and contamination level was $1.5{\pm}0.2\;log\;CFU{\cdot}g^{-1}$. Among foodborne pathogens, Staphylococcus aureus was detected in 1.5%, however, Salmonella spp., Listeria monocytogenes and E. coli O157:H7 were not detected on any of the vegetable samples. We also found undefined parasite eggs from two samples of Chinese cabbages (0.8% of total vegetables we tested). From these study, we found the presence of microbial contamination of agricultural products from urban farming, thus we need further concern to improve the biosafety during production of agricultural products.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.68-76
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• 2008

This study examined the inhibition effects of a freshwater bivalve (Unio douglasiae) and a submerged plant (Potamogeton crispus) on the cyanobacterial bloom (Oscillatoria sp.). The experiment were conducted in aquarium $(50cm{\times}65cm{\times}120cm)$ with lake sediments in the bottom of the aquarium in 10 cm thick. Before the experiments, artificial cyanobacterial bloom was induced with the addition of lake sediment and CB medium. Total 12 transparent acrylic cylinders (${\Phi}19cm$, height 40 cm) were placed in the aquarium, and within which bivalves and plants were placed in various conditions such as the control (C), plant addition (P:5 stems), mussel addition (U:2 individuals), and both mussel and plant addition (PU: the same quantity as used in each treatment). The experiment was conducted in triplicate during 7 days. pH, dissolved oxygen (DO), electric conductivity (EC), salinity, cyanobacterial cell density, chlorophyll-${\alpha}$ concentration, and mussel filtering rate were monitored daily. At the end of the experiment, total phosphorus (TP), total nitrogen (TN), and plant height and weight were measured. Overall, a large degree of cyanobacterial growth inhibition appeared in both P and U treatments, and the effect was highest in the U treatment, followed by P and PU. The combined treatment of both U and P did not show any synergic effects compared to the effect in separated treatment. In all enclosures of the treatments chlorophyll-${alpha}$ (Chl-${alpha}$) concentration decreased until 36 hours after the additions of the plants and mussels. In contrast, Chl-${alpha}$ concentrations increased in PU enclosures after 36 hours. The same trend was shown in the cell density of Oscillatoria. pH and DO gradually decreased until 120 and 144 hours, respectively, in the P and PU enclosures. TP concentration increased in the mussel enclosures (U and PU), while TN concentration largely decreased in the plant enclosures (P and PU). Our results suggest that applied bivalve (Unio) and submerged plant (Potamogeton) seemed to have a potential effect on the growth inhibition of cyanobacteria, but their combined application may have an antagonistic effect to diminish the degree of the inhibition.