• Korean Journal of Soil Science and Fertilizer
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• v.43 no.5
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• pp.637-643
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• 2010

For enhancement of apple productivity, the calcium fertilizers to increase the calcium content of fruit, and reduce the incidence of bitter pit in apples are applied. Crushed oyster shell contains a plenty of calcium carbonate, and a very small amount of boron, ferrous, and manganese. A field study was conducted to determine the optimum level of crushed oyster shell for soil nutrient management, and its effect on the induction of bitter pit in cultivar 'Gamhong' apple. The application of crushed oyster shell increased organic matter, available phosphate, and exchangeable cation concentration in soil. We found a significant positive correlation between soil pH, and application level of crushed oyster shell in both top, and subsoils. The incidence of bitter pit in apple fruit at the harvest stage was significantly higher in non treatment and calciummagnesium carbonate treatment than on over applications 4 Mg $ha^{-1}$ for crushed oyster shell. However, the optimum level of crushed oyster shell was 2 Mg $ha^{-1}$, especially considering the soil Ca content, soil pH, fruits weight, and yield. Our results show that the crushed oyster shell can be effective in restoring the soil nutrient balance, and inducing the bitter pit in apple fruit.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.1
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• pp.45-51
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• 2005

As a silicate source to rice, a coal ash (50%) was mixed with a phosphogypsum (hereafter, gypsum, 50%). Field experiments were carried out to evaluate rice (Oryza sativa) productivity in silt loam (SiL) to which 0, 20, 40 and $60Mg\;ha^{-1}$ of the mixture were added. The mixture increased rice yield and showed the highest yields following the addition of $30Mg\;ha^{-1}$. The mixture did not result in an excessive uptake of heavy metals by the rice grain. The mixture improved available silicate and phosphate and exchangeable calcium contents in soil. The available boron content in soil increased with the mixture application levels up to $1.42mg\;kg^{-1}$ following the application of $60Mg\;ha^{-1}$, but boron toxicity in rice was not found. It is concluded that the coal ash and gypsum mixture could be a good alternative to inorganic soil amendments to restore the soil nutrient balance in paddy soil.

• Journal of Environmental Science International
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• v.13 no.12
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• pp.1089-1102
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• 2004

Seasonal variation of biogeochemical characteristics was determined in Lake Shihwa from October 2002 to August 2003. When the lake was artificially constructed for the freshwater reservoir in 1988, the development of the strong haline density stratification resulted in two-layered system in water column and hypoxic/anoxic environment prevailed in the bottom layer due to oxidation of accumulated organic matters in the lake. Recently, seawater flux to the lake through the sluice has been increased to improve water quality in the lake since 2000, but seasonal stratification and hypoxic bottom layer of the lake still developed in the summer due to the nature of artificially enclosed lake system. As the lake is still receiving tremendous amount of organic matters and other pollutants from neighboring streams during the rainy summer season, limited seawater flux sluicing into the lake may not be enough for the physical and biogeochemical mass balance especially in the summer. The excess of accumulated organic matters in the bottom layer apparently exhausted dissolved oxygen and affected biogeochemical distributions and processes of organic and inorganic compounds in the stratified two-layered environment in the summer. During the summer, ammonia and dissolved organic carbon remarkably increased in the bottom layer due to the hypoxic/anoxic condition in the bottom layer. Phosphate also increased as the result of benthic flux from the bottom sediment. Meanwhile, dissolved organic carbon showed the highest value at the upstream area and decreased along the salinity gradient in the lake. In addition to the sources from the upstream, autochthonous origin of particulate organic carbon from algal bloom in the lake might be more important for sustaining aggravated water quality and development of deteriorated bottom environment in the summer. The removal of trace metals could be attributed to scavenging by strong insoluble metal-sulfide compounds in the hypoxic/anoxic bottom layer in the summer.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.4
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• pp.194-201
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• 2005

Silicate (Si) fertilizers are well-known for soil amendment and to improve rice productivity as well as nitrogen efficiency. In this study, we investigated the possible reduction level of nitrogen fertilization for rice cultivation by amending Si fertilizer application. Field experiments were carried out to evaluate the productivity of rice (Oryza sativa L.) on a silt loam soil, where three levels of nitrogen (0, 110 and $165kg\;ha^{-1}$) were selected and Si fertilizer as a slag type was applied at 0, 1 and 2 times of the recommendation level (available $SiO_2\;130mg\;kg^{-1}$). Application of Si fertilizer increased significantly the rice yield and nitrogen efficiency. With increasing N uptake of rice, 1 and 2 times of recommended levels of Si fertilization could decrease nitrogen application level to about 76 and $102kg\;N\;ha^{-1}$ to produce the target yield, the maximum yield in the non-Si amended treatment. Silicate fertilizer improved soil pH and significantly increased available phosphate and Si contents. Conclusively, the Si fertilizer could be a good alternative source for soil amendment, restoring the soil nutrient balance and to reduce the nitrogen application level in rice cultivation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.3
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• pp.198-205
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• 1982

In 1980, rice was considerably damaged by abnormal low temperature. In this paper, to determine the effect of low temperature on the growth and nutrition of rice, the experiment were carried out: varietal response to low temperature in the region with different elevations. Regional differences of heading response to low temperature were observed among varieties. The difference of days between regions were bigger in tongil lines than Japonica lines. Especially, Milyang 42 and Hangangchalbeo might belong the cold suceptible group, since the varieties were severely delayed their heading in the high mountainous region as comparred to plain region. The delay of heading with low temperature was brought out grain sterility, and fertility and ripening ratio is influenced cold tolerance and elevations, and it's decreased yield. Varieties with higher grain sterility by low temperature have higher total nitrogen content, but tended to have lower potassium and phosphate contents in the flag leaf. High content of total nitrogen, low contents of potassium and silicate were observed in the sterilized grain chaff an the opposite result were noted in the ferilized grain chaff at the ripening stage. The results reveal that the balance of these mineral element may play an important role in ripening and possibly cold tolerance.

• Journal of the Mineralogical Society of Korea
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• v.23 no.1
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• pp.51-61
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• 2010

Ettringite $(Ca_6[Al(OH)_6]_2(SO_4)_3{\cdot}26H_2O)$ is a sulfate mineral that shows a complicate property in concrete. It is often called as "a cancer of concrete" because secondary ettringite formation in hardened concrete often cause expansion and cracking of concrete due to its expansive crystal structure. In the present study, we tested the possibility for crystal growth inhibition of secondary ettringite by crystallization inhibitors that are commercially used for scaling inhibitors in Korea. For the test, we developed a method of ettringite solution synthesis. Three types of crystallization inhibitors were selected and examined the effects On ettringite growth inhibition. The experimental results of ettringite solution synthesis indicated that ettringite was successfully synthesized under condition that the mass balance between calcium hydroxide saturated solution and aluminum sulfate solution was attained. Monosulfate and semisulfate were synthesized when the ratio of $Ca^{2+}$ ions to ${SO_4}^{2+}$ ions was increased. The induction time of ettringite crystallization was less than 2 min. and crystallization was almost completed within an hour. The experimental results of ettringite crystallization inhibition showed that organic PBCT (2-Phosphonobutane-1,2,4-Tricarboxylic Acid) and inorganic SHMP (Sodium Hexametaphosphate) were relatively less effective on ettringite crystallization inhibition under experimental conditions. However, organic HEDP (1-Hydoxyethylidene-1,1-Diphosphonic Acid) effectively prevented ettringite growth with producing amorphous gel phase materials up to inhibitor concentration 0.1 vol.% of aluminum sulfate solution.

• Korean Journal of Soil Science and Fertilizer
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• v.14 no.3
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• pp.117-129
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• 1981

An experiment with the tobacco plant was conducted in the pots. A sandy humic soil was used with 2 levels of pH, 3.5 and 5.8 with 2 kinds of anions, Cl as $NH_4Cl$ and $SO_4$ as $(NH_4)_2SO_4$, and with 4 levels of pF, 1.5, 2.0, 2.5, and 3.5. The pH-treatment created different N-forms; $NH_4$ at low pH(3.5) and $NO_3$ at high pH (5.8). The results are summarized as follows: 1. At low pH (3.5) with high concentration of $NH_4$ given as $NH_4Cl$, the high content of $NH_4$ and Cl in tobacco resulted in plants suffering from $NH_4$ and Cl toxicity as well as Mn toxicity. As a result of these toxicity, an extremly abnormal growth of tobacco was clearly appeared. In the tobacco grown at low pH with $NH_4$ given as $(NH_4)_2SO_4$, a large amount of the $NH_4$ uptake developed Mg and Ca deficiencies. $NH_4-N$, which had been applied to the soil of high pH (5.8), was almost completely transformed into $NO_3-N$ by nitrification and, on this low acidic soil, the plants were all healthy regardless of Cl or $SO_4$ added together with $NH_4-N$. However, dry matter production was higher and maturity faster when $SO_4$ was used as anion than when Cl was used. 2. High moisture content in soil, to some extent, is necessary for a good development and growth of the tobacco plant. Phosphate uptake seemed to be limited at higher moisture stress. The dry matter yield of tops and roots of tobacco were in the order of pF 1.8 > 2.1 > 2.6 > 3.6, respectively. 3. Data of chemical analysis and dry matter yields of tops and roots showed that the tobacco plant followed the normal (C-A) concept. In the normal growth of plants, the carboxylate content of tops was quite comparable to the estimated (C-A) values. If $NH_4$ content of plants remains in quite high quantities, it must be analysed and taken into consideration for the (C-A) calculation. Al is not transported toward tops in toxic amounts due to its high immobility, it mostly stay in or on the roots, probably due to precipitation as a aolt. When Al is present in high quantities, it has to be considered into the (C-A) calculation.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.235-240
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• 2012

This study was conducted to find out the optimum cropping system for the stable production of forage crops in the newly reclaimed land located at Gwanghwal region of Saemangum reclaimed land in which the soil is sandy loam (Munpo series). There were two treatments of nitrogen fertilization 20% increment based on the standard fertilization of 150, $200kg\;ha^{-1}$. Whole crop barley as the winter crop sowed on 27 October. After the whole crop barley was harvested at the end of May. Corn and sorghum${\times}$sudangrass as the summer crop sowed at the early of June successively on the same field. Emergence rate the whole crop barley was high while the summer crops were low. Soil salinity was increased during cultivation of summer crops. However, corn and sorghum${\times}$sudangrass were not damaged by salt. Increase of nitrogen fertilization made the growth of cultivation crops good, stem and leaf tended to have a lot of the mineral nutrients at heading stage and silking stage. After experiment, among soil chemical properties pH, content of exchangeable sodium were decreased and content of organic matter, available phosphate were increased. Dry matter yield were showed whole crop barley $13,170kg\;ha^{-1}$ and sorghum${\times}$sudangrass $19,440kg\;ha^{-1}$ by increment of nitrogen fertilization. Therefore, to improve the product and nutrient balance of reclaimed saline land comprehensive soil management should be considered.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.3
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• pp.162-168
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• 2002

The silica uptake of rice plant(Oryza sativa L.) and a potential capacity of paddy soil as a source of silica supply for rice plant was studied under field experimental condition. Amount of Si from irrigation water, rainfall, which was a source of silica supply, and percolating rate of water through paddy soil profile as a source of silica loss from paddy soil, was investigated. Rice plants were grown in three different conditions, which included Control as non-fertilized, RDA's recommandation(NPK, Urea-Fused phophate-Potassium chloride=$110-45-57kg\;ha^{-1}$) and RDA's recommandation with supplement of silicate fertilizer(NPK+Si, Urea-Fused phosphate-Potassium chloride+Si=$110\;N-45\;P_2O_5-57\;K_2O+267.2\;Si\;kg\;ha^{-1}$). An amount of silica supply from rainfall was $0.5kg\;ha^{-1}$ and average amount of silica supplied from irrigation water $42.5kg\;ha^{-1}$, ranging from $28.1kg\;ha^{-1}$ to $58.8kg\;ha^{-1}$. Silica amount percolated through the soil profile have uniform trend comparatively showing $62.9kg\;ha^{-1}$ in Control, $64.8kg\;ha^{-1}$ in NPK treatment and $62.9kg\;ha^{-1}$ in NPK+Si treatment. Silica uptaked by Rice plant was $335.6kg\;ha^{-1}$ in Control, $406.6kg\;ha^{-1}$ in NPK+Si treatment and $471.1kg\;ha^{-1}$ in NPK+Si treatment. The difference between an amount of Si input(from rainfall, irrigation water and silicate fertilizer) and an amount of Si output(percolated Si in soil, uptaked Si by rice plant) was $357.4kg\;ha^{-1}$ in control, $412.1kg\;ha^{-1}$ in NPK treatment and $238.2kg\;ha^{-1}$ in NPK+Si treatment. Results of our study imply that paddy soil is a potential pool as a source of Si supply during growing periods of rice plant.

• KSBB Journal
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• v.18 no.3
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• pp.211-216
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• 2003

The removal yield of dissolved organic matter in drinking water by biological activated carbon (BAC) process was investigated. The tested processes wer raw water-AC process (BAC1), raw water-ozonation-BAC process (BAC2), and raw water-ozonation-coagulation/sedimentation-BAC process (BAC3). The amounts of organic matter was measured as dissolved organic carbon (DOC), ulta-violet radiation at 254 nm wavelength ($UV_{254}$), total nitrogen (T-N), ammonia nitrogen (NH_3$-N), and total phosphate (T-P). As a results, 30.7% DOC was removed by BAC2 process, which showed higher removal efficiency than BAC1 or BAC3 processes. The removal yield of $UV_{254}$ in BAC1, BAC2, and BAC3 processes were observed as 45.3%, 44.6%, 58.4%, respectively. And the removal yield of ammonia nitrogen were 66%, 81%, 29% in each BAC processes. The optimal empty bed contact time (EBCT) of BAC processes was estimated as 10 minute. This study has shown that BAC process combined with ozone treatment was efficient for removing dissolved organic matter in water.