• YAKHAK HOEJI
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• v.42 no.2
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• pp.153-158
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• 1998

Calcium hydrogen phosphate was synthesized by reacting calcium chloride and sodium hydrogen phosphate solution in this study. It is well known that the particle size and yield o f calcium hydrogen phosphate produced is greatly affected by the synthetic conditions such as the reactant concentration, reaction temperature, reacting fine, mole ratio and drying temperature, etc. The purpose of this study is to investigate the optimum synthesis condition from the viewpoint of yield and sedimentation volume of the prepared calcium hydrogen phosphate powder according to a randomized complete block design proposed by G.E.P. Box and K.B. Wilson. It was found that the optimum synthetic conditions of calcium hydrogen phosphate were as follows: It was found that optirnum temperature range of reactant solutions was $28-38^{\circ}C$ and $32-42^{\circ}C$ respectively, on the viewpoint of yield and sedimentation volume. The optimum concentration range of reactant solutions was 5.5-10.0% and 6.9-7.4% respectively, on the viewpoint of yield and sedimentation volume. The optimum mole ratio of $CaCl_2$ to $Na_2HPO_4$ was in the range of 1.2-2.0 and the optimum reacting time range was 8.5-11.0 minutes. The optimum drying temperature range was $39-41^{\circ}C$ from the viewpoint of yield, but it was $39-43^{\circ}C$ on the basis of sedimentation volume. Crystallographic analysis to X-ray diffraction patterns of commercially available ecalcium hydrogen phosphate and calcium hydrogen phosphate samples prepared in this study suggested that all samples tested belonged to monoclinic crystal system characteristic of $CaHP0_4{\cdot}2H_20$ crystals.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.5
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• pp.434-439
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• 2016

Anthropogenic soil in cropland is formed in the process of subsoil reversal and the refill of soil into cropland. However, there was little information on the chemical properties within soil profiles in anthropogenic soil under rice paddy near the river. In this study, we investigated the chemical properties within soil profiles in the anthropogenic soil located at 4 sites in Gumi, Kimhae, Chungju, and Euiseong to compare with the natural paddy soil near the river. Among particle sizes, the sand content decreased under soil profiles but the silt and clay contents increased compared to the natural paddy soil in soil profiles. Organic matter content in topsoil of anthropogenic soil was lower than in that of natural soil, which was shown the contrary tendency within soil profiles. Also, the soil pH, available $P_2O_5$, and exchangeable cations were higher in anthropogenic soil compared to natural paddy soil at topsoil, which was maintained these tendency into soil depth. Nutrients may be equally distributed in anthropogenic soil during the process of refill in paddy soil near the river. This results indicated that anthropogenic soil would contribute to carbon sequestration, the mitigation of compaction, and reduction of fertilizer application in paddy soil. Therefore, characteristics of anthropogenic soil can be used for the soil management in cropland.

• Economic and Environmental Geology
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• v.41 no.2
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• pp.201-210
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• 2008

The mixing treatment process using lime (CaO) and limestone ($CaCO_3$) as the immobilization amendments was applied for heavy metal contaminated filmland soils around Goro abandoned Zn-mine, Korea in the batch and pilot scale continuous column experiments. For the batch experiments, with the addition of 0.5 wt.% commercialized lime or limestone, leaching concentrations of As, Cd, Pb, and Zn from the contaminated filmland soil decreased by 70, 77, 94, and 95 %, respectively, compared to those without amendments. For the continuous pilot scale column experiments, the acryl column (30 cm in length and 20 cm in diameter) was designed and granulated lime and limestone were used. From the results of column experiments, with only 2 wt.% of granulated lime, As, Cd, and Zn leaching concentrations decreased by 63%, 97%, and 98%, respectively. With 2 wt.% of granulated limestone, As leaching concentration reduced from 135.6 to 30.2 ${\mu}g/L$ within 5 months and maintained mostly below 10 ${\mu}g/L$, representing that more than 46% diminution of leaching concentration compared to that without the amendment mixing. For Cd and Zn, their leaching concentrations with only 2 wt.% of limestone mixing decreased by 97%, respectively compared to that without amendment mixing, suggesting that the capability of limestone to immobilize heavy metals in the filmland soil was outstanding and similar to that of lime. From the column experiments, it was investigated that if the efficiency of limestone to immobilize heavy metals from the soil was similar to that of lime, the limestone could be more available to immobilize heavy metals from the soil than lime because of low pH increase and thus less harmful side effect.

• Korean Journal of Food Science and Technology
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• v.49 no.6
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• pp.617-624
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• 2017

Chocolate, one of the most popular confectioneries in the world, is known for its aromatic flavor and high antioxidant activities. In this study, we investigated the effects of fermentation with commercially available lactic acid bacteria, ABT-5, on the flavor and antioxidant activities of dark chocolate. During 24 h fermentation, pH decreased from 5.52 to 3.97 and total acidity increased from 0.51 to 1.85%, whereas total polyphenol and flavonoid contents as well as DPPH and ABTS radical scavenging activities remained unchanged. Furthermore, compared with control HepG2 cells treated with unfermented dark chocolate, those treated with the fermented dark chocolate showed significantly lower levels of reactive oxygen species and higher viability under $H_2O_2-induced$ oxidative stress. Finally, GC-MS and headspace GC-MS analysis detected 4-hydroxy-2,5-dimethyl-3(2H)-furanone and 2-furanmethanol, known to enhance flavor, in the fermented dark chocolate. Collectively, these results suggest that ABT-5-fermented dark chocolate could be utilized for developing value-added dark chocolate products.

• Korean Journal of Soil Science and Fertilizer
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• v.11 no.1
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• pp.43-50
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• 1978

In order to compare the effectiveness of different phosphorus forms (pulverized as regranulized) and formulars (compound fertilizers) of fused phosphate and to compare the effectiveness of boron from different forms (straight borax, granulized with fused phosphate and included in compound fertilizer), a field experiment was conducted on a relatively fertile upland soil using soybean as a test crop. Results are summarized as following. 1. Yield of soybean was significantly higher in the plots fertilized with P when compared to check plot (no p). However, no significant differences were observed among the different forms or formulars of fused phosphate, indicating that the regranulization or formulation of compound fertilizer did not influence the effectiveness of phosphorus. 2. The application of boron, regardless of its formular, brought about higher B content in plant tissue and higher grain yield. There was a tendency that boron contained in ragranulized fused phosphate was more effective than straight borax. The results also indicated that when boron is to be included in NPK compound fertilizer, its content should be at the least 1.5% as $B_2O_3$. 3. The effectiveness of boron appeared as increased number of pod, higher B, and Ca contents in plant and the amounts of uptake of these elements by soybean. 4. The analysis of soil after the experiment indicated that different forms or formulars of fused phosphate were similarly effective in increasing the available P, Ca, and Mg contents in the soil. 5. Slight increase in available B contents in the experimental plot soils applied with boron fertilizer was observed after the trial.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.4
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• pp.259-267
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• 1990

This study was carried out by investigating the changes of physico-chemical and mechanical properties of Gwanghwal and Poseung series in order to obtain basic information on the soil improvement and management. 1. In Gwanghwal series, the content of salt in soil and ground water before rice transplanting at the 21st year after reclamation were 0.29 and 1.02 percent respectively, and the safty cultivation of paddy rice was possible after 33 years of reclamation in both soil series. 2. Clay contents. atterberg limits and clay activity according to the age of reclaimation showed negative correlation. but sand content and N-value were positive in them. 3. Cone index was lower than $3kg/cm^2$ for the first 5 years after reclaimation in both soil series, and the formation of hard pan were 33rd and 49th year after reclamation in Gwanghwal and Poseung series respectively, and its thickness was more in Poseung than in Gwanghwal series. 4. Shearing resistance decreased with the age of reclaimation in both soil series. and friction resistance increased in Gwanghwal than Poseung siries. 4. Shearig resistance decreased with the age of reclaimation in both soil series, and friction resistance increased in Gwanghwal than Poseung series. 5. Soil pH. available, $SiO_2$, $Mg^2$, $K^+$, $Na^+$ and C. E. C showed negative correlation. with the year cultivated paddy rice. but O. M. ava ilable $P_2O_5Ca^{2+}$ and T-N had positive one in both soil series. Contents of O. M and $Ca^{2+}$ and T-N had positive one in both soil series. Contents of O. M and $Ca^{2+}$ were high in Gwanghwal, but C. E. C. was in Poseung series.

• Korean Journal of Poultry Science
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• v.36 no.2
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• pp.133-137
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• 2009

This study was conducted to evaluate the performance of Cherry Valley and Grimaud strain. A total of two hundred eighty eight, one day old duck breeders (Cherry Valley and Grimaud strain) were randomly divided into two groups with 4 replicates of 36 birds each and fed a commercially available diet for 24 weeks. Overall body weight gain was significantly higher in Cherry Valley (3,064 g) than in Grimaud strain (2,851 g). Feed intake was significantly increased in Grimaud strain compared with Cherry Valley strain (p<0.05). Viability of Grimaud strain showed 100.0% and was higher than that of Cherry Valley strain. Uniformity was not statistically different between Cherry Valley and Grimaud strains.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.4
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• pp.71-80
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• 2001

In order to evaluate the effectiveness of the organic and natural farming techniques, the actual conditions of the techniques were surveyed and some crops were cultivated in situ. The contents of available $P_2O_5$, exchangeable $Ca^{2+}$ and organic matter of the organic and natural farming soil as well as soil pH were higher than those of the non-organic and non-natural farming soil, and especially the content of organic matter amounting 54.0 g/kg was dominant. Income of the farmers cultivating the different crops with the organic and natural farming was high in order of red pepper in vinyl house > cucumber in vinyl house > fruit(pear) > lettuce in vinyl house > rice. The agricultural materials used in organic and natural farming were ranged from 22 to 25 kinds, representing low pH amounted from 2.9 to 4.5 and low contents of fertilizer ingredients. The expense for purchasing the materials was from three to five times higher than that of soil testing plot. The yields of test crops in the organic and natural farming plots were lower than those of soil testing plot, and the efficiencies of the disease and pest control by the application of the substitutes for pesticide were lower than those by pesticides.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.553-557
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• 2014

The steady increase in livestock industry has greatly required the stable production of food and forage crops. As an alternative, rice-forage cropping system has been attempted in several southern areas. The present study was performed to understand whether an application of cattle-manure compost affects soil chemical properties and crop productivity in rice-forage cropping system, rice ${\rightarrow}$ summer oat ${\rightarrow}$ rye, in Jangheong county, south Jeolla province from 2013 to 2014. Treatments was composed of control (no compost), CM1 (compost application before rice transplanting), and CM2 (two-times compost application, before rice transplanting and after rice harvest), and inorganic fertilizers (N, P, and K) were equally dressed in all plots. Yields of rice were not significantly different between treatments, however, oat production was 1.25-fold higher in CM1 and CM2. Nutrient uptake amounts of rye were higher in CM2 than CM1 and control. Total nitrogen in soil was maintained stable level during crop cultivation. And soil organic matter contents in all treatments were increased by crop residue. Available P_2O_5$ and exchangeable K were increased by cattle manure application. Therefore, it suggested that the amount of nutrient by forage crop residue should be considered in rice-forage multiple cultivation.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.2
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• pp.135-139
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• 1990

This study was carried out to find favourable soil conditions to give quality of Astragali Radix. Plants were grown in the soils of different physico-chemical properties, and ash, ethanol extract and free sugars from their roots were analyzed. Fructose and sucrose extracted from the root were determined by HPLC. The contents of Fe were 6.2~7.6 ppm. The ash contents of the root were positively correlated with the available $P_2O_5$ in the soils as well as P and K in the root.