• Korean Journal of Soil Science and Fertilizer
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• v.31 no.3
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• pp.271-276
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• 1998

This experiment was carried out to investigate the changes on nutrient uptake and yields of onion when it was applied with urea and ammonium sulfate as nitrogen fertilizer types; potassium chloride and potasssium sulfate as potassium fertilizer types and lime requirement and phosphorus absorption coefficient controlled 5% as soil improvement index. The variety of onion used was CheonJuHwang and the soil used was Yonggye series in the Jeonnam Muan area. The amounts of N, P and K uptake were higher in the mixed application plot of ammonium sulfate and potassium sulfate than in the plot of urea or potassium chloride. The sulfate content of soil was higher in the period of plant growth than in the harvest stage. The sulfate content of plant was highest in the harvest stage and this content was higher in the stem and in the leaf than in the bulb. The sugar content of onion was 7.43~8.23 Brix content was higher in the large bulb than in the small bulb. The weight of dry matter and the rate of good quality were high in the mixed application plot of ammonium sulfate and potassium sulfate, so the yield of onion was increased 2~6% compared with control.

• Korean Journal of Organic Agriculture
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• v.17 no.3
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• pp.381-391
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• 2009

Crop production can be secured by the cycle of green manure crops as an alternative of the chemical fertilizer. Recently, rapeseed (Brassica napus L.) has been cultivated in the south part of Korea for the production of biodiesel. In this research, we focused on recycling rapeseed residue, which is produced after harvesting the rapeseed for biodiesel, as a potential source of nitrogen to the succeeding crop. Pot experiment was conducted to evaluate the effects of winter rapeseed as green manure on mineralization and uptake of nitrogen to the succeeding corn (Zea mays L.). Result showed that total nitrogen and C/N ratio of rapeseed at the harvesting stage was 0.54% and 63, respectively. The incorporation of rapeseed without decomposition period slightly inhibited nitrogen uptake to the succeeding corn compared to those with 30 days decomposition period. The pH and EC values of soils increased by increasing the period of decomposition of rapeseed from 5.2 to 6.4 and from 0.05 dS/m to 0.21 dS/m, respectively. Significant amounts of $NH_4^+$ and $NO_3^-$ are released by incorporation of rapeseed. The succeeding corn took up 86% and 88% of inorganic nitrogen released from the rapeseed with and without decomposition period, respectively. The overall results suggested that the utilization of rapeseed residue as green manure can be an alternative source of nitrogen in corn-rapeseed double cropping system.

• Polymer(Korea)
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• v.36 no.1
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• pp.98-103
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• 2012

Poly(2,6-dimethyl-1,4-phenylene ether) (PPE) was synthesized using $Cu(NO_2)_2{\cdot}3H_2O$ or CuCl catalyst with various amounts of ligand and base in several different solvent systems. CuCl/1-methylimidazole/ammonium hydroxide was found to be an effective catalyst system which showed the highest polymer yield and molecular weight. The effects of catalyst/monomer ratio, different amine ligands, and the content of mono-functional reagent 2,4,6-trimethylphenol (TMP) additive on the polymer yield and molecular weight were investigated. Among the co-solvent systems used in this polymerization, chloroform/methanol 9/1(v/v) gave the highest polymer yield and molecular weight ($\overline{M_n}$ 55 K, $\overline{M_w}$ 92 K, PDI 1.7). The catalytic activity between CuCl and CuI was compared by oxygen-uptake experiments and the formation of sideproduct, 5,5'-tetramethyl-4,4'-diphenoquinone (DPQ), was analyzed by ultraviolet spectroscopy.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.1
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• pp.60-65
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• 2016

The main objective of this research was to estimate the total mass of nitrogen discharged from various sources in paddy field area of South Korea in 2010 and 2013. Input and output budgets for nitrogen were estimated by mass balance approach. The mass balance approach reduces the effect of flow variations, and the large scale approach minimizes local effects, resulting in easier and faster establishment of strategy for nonpoint pollution problems. Nitrogen inputs were chemical fertilizer, compost, atmospheric deposition, biological fixation, and agricultural water, while crop uptake, denitrification, volatilization, and infiltration were nitrogen outputs. The estimated total nitrogen inputs for paddy field in South Korea were $266,211ton\;yr^{-1}$, $260,729ton\;yr^{-1}$, while those of total nitrogen outputs were $168,463ton\;yr^{-1}$, $164,994ton\;yr^{-1}$ in 2010 and 2013, respectively. Annual amounts of potential nitrogen outflow from paddy field were $97,748ton\;yr^{-1}$, $95,735ton\;yr^{-1}$ in 2010 and 2013. Also, annual rate of potential nitrogen outflow were 36.7%, 36.7% in 2010 and 2013, respectively.

• Korean Journal of Weed Science
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• v.7 no.3
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• pp.247-256
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• 1987

The ability of three Echinochloa colona (L.) Link ecotypes to compete with rice (Oryza sativa L.) was evaluated. For all the ecotypes, E. colona was shorter and produced less leaf area and dry matter than rice at 15 days after seeding (DAS), whereas the reverse was observed from 30 to 60 DAS. Neither E. colona nor rice tillered during the first 15 DAS, but E. colona had greater accumulative tiller length than rice from 15 DAS. Rice absorbed more nitrogen than E. colona at 15 DAS. E. colona absorbed greater amounts of nitrogen, phosphorus, and potassium than did rice between 30 and 60 DAS and increase in its density decreased the nutrients uptake of rice. Differences in the competitive ability of the ecotypes were related to the growth characteristics of the ecotypes and the period of competition between the two species. At the early growth stages the Pangasinan ecotype, which increased plant size rapidly and had a shorter life cycle, was more competitive against rice than the Leyte and South Cotabato ecotypes, which had a longer vegetative growth period. However, the reverse was observed at the later growth stages of the ecotypes.

• Restorative Dentistry and Endodontics
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• v.13 no.1
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• pp.69-78
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• 1988

The study was designed to establish a more nearly quantitative method for assessing the marginal leakage of dental restorations. 27 Class V cavities with $45^{\circ}$ bevel joint were prepared and classified into 2 groups. One group was filled with Scotchbond and silux. The other group was filled with glass ionomer cement, Scotchbond and silux. After finishing, all specimens were subjected manually to 100 thermal cycles at $0^{\circ}C$ and $100^{\circ}C$ water-bath. They were soaked in a samarium nitrate solution for 3 hours, irradiated with flux of $6{\times}10^{12}$ neutrons/$cm^2$/sec for 11 hours, cooled for 200 hours, counted with the HPGE detector and the tracer uptake was determined by comparison with a standard of samarium (10 ${\mu}g$). The following results were obtained. 1. Both of the two groups showed a considerable amounts of marginal leakage. 2. The group filled without glass ionomer cement base showed more marginal leakage than the group filled with glass ionomer cement base. 3. Neutron Activation Analysis produced a good quantitative method to measure the marginal leakage and samarium was appropriate to measure the marginal leakage of resin restorations using neutron activation analysis.

• Korean Journal of Organic Agriculture
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• v.19 no.spc
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• pp.182-185
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• 2011

Soil $NH_4$-N content became higher in proportion to the increase in the urea application rate, while in livestock faeces compost (LFC) plots, it became lower than in urea plots and had no significant difference statistically among LFC plots. There was a close relationship between phosphate fertilization rate and the increment of soil available phosphate content after experiment resulting y=0.1788x-6.169 ($R^2=0.9425$) when applied fused superphosphate fertilizer, and y=0.0662x-2.689 ($R^2=0.9315$) when applied LFCs by the same amounts of phosphate (x: phosphate application, kg $ha^{-1}$, y: increment in soil available phosphate content, mg $kg^{-1}$. Plant height, number of stems, nutrients uptake by rice and rice yield showed higher levels in N 100, 150% application plots of chemical fertilizers, while every LFC plots exhibited lower values and no significant difference among them. Relative nitrogen fertilization efficiencies of LFCs compared to urea was 12.3% for cattle faeces compost (CaFC), 8.8 for swine faeces compost (SwFC) and 24.6 for chicken faeces compost (ChFC), respectively.

• Toxicological Research
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• v.35 no.4
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• pp.311-317
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• 2019

The transport systems for metals play crucial roles in both the physiological functions of essential metals and the toxic effects of hazardous metals in mammals and plants. In mammalian cells, Zn transporters such as ZIP8 and ZIP14 have been found to function as the transporters for Mn(II) and Cd(II), contributing to the maintenance of Mn homeostasis and metallothionein-independent transports of Cd, respectively. In rice, the Mn transporter OsNramp5 expressed in the root is used for the uptake of Cd from the soil. Japan began to cultivate OsNramp5 mutant rice, which was found to accumulate little Cd, to prevent Cd accumulation. Inorganic trivalent arsenic (As(III)) is absorbed into mammalian cells via aquaglyceroporin, a water and glycerol channel. The ortholog of aquaporin in rice, OsLsi1, was found to be an Si transporter expressed in rice root, and is responsible for the absorption of soil As(III) into the root. Since rice is a hyperaccumulator of Si, higher amounts of As(III) are incorporated into rice compared to other plants. Thus, the transporters of essential metals are also utilized to incorporate toxic metals in both mammals and plants, and understanding the mechanisms of metal transports is important for the development of mitigation strategies against food contamination.

• Korean Journal of Agricultural Science
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• v.49 no.3
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• pp.463-481
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• 2022

Phosphorous (P) is considered to be one of the key essential elements demanded by crop plants. Approximately 70 - 90% of phosphatic fertilizers applied to crops are fixed in soil as Ca, Fe, and Al metal cations, which are insoluble and thus not readily available for plant uptake. Therefore, most soils are deficient in plant available P. This is usually rectified by applying phosphate fertilizers continuously, although this is not economically viable or environmentally acceptable. The present paper reviews the mechanisms involved with phosphate solubilization and mineralization by phosphate solubilizing microorganisms (PSMs) with the associated factors that determine the success. PSMs are effectively involved in mediating the bioavailability of soil P. Their contribution includes mineralization of organic P solubilization of inorganic P minerals, and storing sizable amounts of P in biomass through different mechanisms such as the production of organic and inorganic acids, H₂S, siderophores, exopolysaccharides, and production of enzymes such as phosphatases, phytase, and phosphonatases/C-P lyases, which are capable of chelating the metal ions, forming complexes, and making plant available P. PSMs manifest a wide range of metabolic functions in different environments, resulting in significantly higher plant growth, enhanced soil properties, and increased biological activities. Therefore, development of bio-inoculants with efficient novel PSM strains and further investigations on exploring such strains from diverse ecological niches with multifunctional plant-growth-promoting traits are needed.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.3
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• pp.217-221
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• 1986

A column test was conducted to find out the effect of application of slaked lime, calcium sulfate, calcium superphosphate, and phosphoric acid on the solubility of lead in soil. The soil was adjusted to 310.8 ppm concentration of Pb and applied with amounts of calcium equivalent to 600, 1000, 2000 ppm as slaked lime; sulfate 144, 288, 432 ppm as calcium sulfate; phosphate 95, 190, 285 ppm as calcium superphosphate and phosphoric acid, respectively. The results obtained are as follows: 1. The increasing application of improvement agents reduced the amounts of water soluble Pb in soil. Phosphoric acid was the most effect among to the treatments. 2. The slaked lime treatment has the highest pH of soil and the lowest at the phosphoric acid one. The soil Eh has a reverse tendency the soil pH. 3. Water soluble Ca, $PO_4$ and $SO_4$ contents increased with increasing application amounts of improvement agents in soil. 4. $1N-NH_4$ OAC soluble Pb content in soil was a decreasing tendency in the order of calcium superphosphate, phosphoric acid, slaked lime, calcium sulfate and control after experiment.