• Journal of Soil and Groundwater Environment
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• v.21 no.6
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• pp.56-66
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• 2016

Generally, the contribution of crop-intake pathway (CIP) is remarkable in human health assessment (HHA) of heavy metal contamination. Although the crop exposure concentrations (Cp) should directly be used for calculating the average daily dose (ADD) of CIP, the soil exposure concentration (Cs) multiplied by soil-crop bio-concentration factor (BCF) has frequently been used instead of using Cp values. Thus, the BCF values are significant in the HHA, and care should be taken to ensure the reasonable acquisition of BCF values. Meanwhile, the BCF values are known to be significantly affected by analytical methods. Nevertheless, they have been calculated from the concentrations of soil and crop analyzed by only one method: total digestion (aqua regia extraction). For this reason, this study was initiated to seek appropriate soil analysis methods for effective computation of the ADD of CIP. The concentrations of 5 metal contaminants (As, Cd, Cu, Pb, and Zn) in 127 soil samples obtained from 4 abandoned metal mine areas were analyzed by several methods including total digestion and partial digestions using 0.1/1 N HCl, 1M $NH_4NO_3$, 0.1 M $NaNO_3$, and 0.01M $CaCl_2$. The heavy metal concentrations in 127 crop samples (rice grains) were analyzed by total digestion as well. Using the concentrations of soils and crops, the BCF values of each contaminant were calculated according to the kind of soil extraction methods applied. Finally, the errors between Cp and $C_s{\times}BCF$ were computed to evaluate the relevance of each method. The results indicate that the partial extraction using 0.1 N and 1 N HCl was superior or equivalent to total digestion. In addition, the 0.1M $NaNO_3$ method combined with total digestion is recommended for improving the reliability of BCF values.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.1
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• pp.1-6
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• 2004

Agricultural recycling of livestock wastes by composting has lots of beneficial effects on crop production and soil fertility. Most of composts are made from pig manure and water content controller such as saw dust, bark, rice hulls etc. by aerobic processing. But the insufficient supply of saw dust, bark etc. cause the indiscreet use of industrial waste having heavy metals and toxic synthetic chemicals. This research investigated the present quality status of organic by-product fertilizers, and suggested the way of quality interpretation under the statistical approaches based on median, mean and weighted average value. Since the data of one hundred of samples for heavy metal contents (Cd, Pb, Cu, and Cr) and OM/N showed extremely left-skewed distribution, the median was more useful than the mean in representing the characteristics of distribiition for each items. The weighted average value will be a useful index for the quality based on the total amount of producing.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.2
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• pp.55-58
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• 2004

The objective of this study was to get information about water retention characteristics of horticultural substrates used in Korea determined by European standard method. Water retention curves were prepared at water volume (v/v, %) in relation to -10 cm, -50 cm, -100 cm water pressure head. Water retention curves showed different properties depending upon the type, the place of origin, particle size, and manufacturing processes of substrates. Peat and coir had easily available water content in the range of 30-40% and showed high water holding capacity, water buffering capacity, and aeration for plant growth. However, bark, sawdust and rice hull showed low water holding capacity about below 10%. The easily available water content of perlite and clay ball was low about 0.1-13.8%, whereas that of vermiculite and rockwool granulate was high about 25.9-52.0%. Understanding water retention characteristics of growing substrates is very important in cstablisliing optimum condition for plant growth. Further study on water retention curves for more substrates, mixture and growing media is needed.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.2
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• pp.123-127
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• 1990

The results of the investigation on the relationship between the varietal difference of photosynthesis capacity and carbohydrate metabolism and the susceptibility to sudden wilting are as follow: 1. Yushin and Milyang 23, varieties in which sudden wilting occurs easily, showed that the photosynthesis capacity at the young panicle formation stage and the contents of chlorophyll of the flag leaf were lower than Jinhung which did not show sudden wilting. 2. Respiration consumption index (${\frac{amount\;of\;respiration}{amount\;of\;assimilation}{\time}100$) of Yushin and Milyang 23 were higher than Jinhung's. 3. Regarding sugar contents of each internode at the ripening stage, the contents of the second and third internodes of Yushin were lower than Jinhung, but no varietal difference was found in the 1st internode. 4. The starch content of the Yushin node sharply decreased compared with Jinhung at the ripening stage. In Jinhung it was especially higher in lowerinternodes, but in the third internode of Yushin. was not more than 50% of that in higher internode's.

• Korean Journal of Soil Science and Fertilizer
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• v.5 no.1
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• pp.33-39
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• 1972

For the increase of productivity, canopy structure and nutritional status in various productivity grades (high>700, medium>600 and low>500kg/l0a as head rice) were investigated in a study using Jinheung(Oryza sativa L.) for the increase of producticity with following results: 1. High yield plot showed greater leaf area and slow decrease of it after heading stage. While low yield plot had rapidly decrease of leaf area. 2. High yield plot showed higher light transmission ratio (LTR) durnig early grow stage, low LTR. during late grow stage, and higher leaf area per LTR. 3. Net assimilation ratio was decrease with the increase of leaf area index (LAI) and it was always higher in high yield plot. 4. High yield plant had greater amount of total nitrogen uptake, slow uptake rate, and considerable uptake after heading while low yield plant showed higher uptake of nitrogen in early stage of growth and no uptake after heading. 5. The percent ratio starch at heading to total at harvesting was 40% for low yield plant and 10% for highyield plant inderting that high yield depends much on past-heading starch synthesis. 6. Main factor determining secondary yield was ripened grain ratio.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.973-982
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• 2012

Crop safety in heavy metal contaminated agricultural field has been a critical issue in Korea and various remediation methods are proposed for minimizing heavy metal transfer from soil to crops. The main objective of this research was to evaluate remediation efficiency of two chemical amendments, lime and steel slag, and to decide extractant for assessing bioavailability of heavy metals. In order to select optimum extractant for evaluating bioavailability of heavy metals, four different single extractants, HCl, DTPA, $CaCl_2$, $NH_4NO_3$, and sequential extraction method were examined. Both chemical amendments showed high immobilization effect for Cd (66%, $33.62mg\;kg^{-1}$) and Pb (74%, $27.65mg\;kg^{-1}$) in soil by HCl extractant. In terms of heavy metal concentration in rice grains, concentrations for Cd (77%, $0.023mg\;kg^{-1}$) and Pb (82%, $0.039mg\;kg^{-1}$) decreased, with addition of chemical amendments. HCl, DTPA, and sequential extractant showed the higher correlation between heavy metal concentration in soil and crops than others. These results indicated that they could be used for assessing bioavailability of heavy metals.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.955-960
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• 2012

In most agricultural soils, ammonium ($NH_4{^+}$) from fertilizer is quickly converted to nitrate ($NO_3{^-}$) by the process of nitrification which is crucial to the efficiency of N fertilizers and their impact on the environment. The salinity significantly affects efficiency of N fertilizer in reclaimed tidal soil, and the soil pH may influence the conversion rate of ammonium to nitrate and ultimately affect nitrogen losses from the soil profile. Several results suggest that pH has important effects on recovery of fall-applied N in the spring if field conditions are favorable for leaching and denitrification except that effects of soil pH are not serious under unfavorable conditions for N loss by these mechanisms. Soil pH, therefore, deserves attention as an important factor in the newly reclaimed tidal soils with applying N. However, fate of N studies in a newly reclaimed tidal soils have been rarely studied, especially under the conditions of saline-sodic and high pH. Therefore, understanding the fate of nitrogen species transformed from urea treated into the reclaimed tidal soil is important for nutrient management and environmental quality. In this article, we reviewed yields of rice and fate of nitrogen with respect to the properties of reclaimed tidal soils.

• Horticultural Science & Technology
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• v.28 no.4
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• pp.580-584
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• 2010

The effect of planting densities on the growth of $Sedum$ $samentosum$ (4 collections) was investigated using nutrient film technique (NFT) with Yamazaki' lettuce nutrient solution (1982) from September 5th to October 24th in non-heating plastic film house. At 40 days, the plant height of 4 collections showed the range of 15.0-18.9 cm, and mean plant height was high the order of $10{\times}10$, $2.5{\times}2.5$, and $5{\times}5cm$. The growth of 'Pohang' and 'Wando' collections was better compared to that of 'Gunsan' and 'Wanju' collections. Number of node, stem diameter, and fresh and dry weight per plant were decreased in higher planting density. Despite the lower fresh weight per plant obtained, the fresh yield per $m^2$ was significantly increased in higher planting density. The mean fresh yield was $14.9kg{\cdot}m^{-2}$ in $2.5{\times}2.5cm$, and 'Pohang' collection showed the highest fresh yield ($17.6kg{\cdot}m^{-2}$). The first optimized harvesting time base on plant height was 30-40 days after NFT culture during autumn season. In eating quality, compression force of stem and bitterness of shoot were decreased in higher planting density. However, the heavy labor demanding high density cutting needs to be improved for hydroponic culture of $S.$ $samentosum$.

• Korean Journal of Community Nutrition
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• v.1 no.1
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• pp.61-70
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• 1996

Correlations of adolescents' blood pressure with dietary factors and blood or urinary electrolytes were investigated in this study. Through the screening for blood pressures of 960 middle school students aged 13-16 years, 30 students with the mean value of SBP and DBP above 96th percentile(high blood pressure group) and the other 30 with the mean blood pressure between 48th and 52th percentiles(normal blood pressure group) were selected as the subjects. SBP/DBP of the high and talc normal blood pressure groups were $141.8{\pm}9.0$ / $83.6{\pm}5.1$ mmHg and $116.4{\pm}3.5$ / $69.8{\pm}3.7 mmHg$, respectively. The average values of age, weight, height, BMI, degree of relative crude physical activity, and family income were not different between two groups. Among nutrients for which intakes were determined by 24 hour-recall and expressed as percent RDA, intakes of total and animal calcium were lower in the high blood pressure group compared to the normal, and were negatively correlated with both SBP and DBP even when the effects of related general and other dietary factors were excluded. Whereas energy, total, animal and vegetable protein, total and animal lipid, and riboflavin were higher in intake in the high blood pressure group than in fille normal, and they were in positive correlations with SBP and/or DBP. Vitamin A and ascorbic acid intakes were also negatively correlated with DBP, though ascorbic acid intake was not different between two groups. High blood pressure group preferred higher concentration of thin rice gruel than normal group and talc preferred salt concentrations was ill positive correlation with SBP. Serum and urinary levels of Ca, Mg, Ca/Mg ratio, Na, K and Na/K ratio did not show any differences between two groups. However serum Ca/Mg retio was in negative and se겨m Mg was ill positive correlations with SBP, and urinary Na excretion was negatively correlated with SBP. Calcium intake showed negative correlation with serum Ha and Na/K ratio. Our data indicated that dietary intake of Ca, energy, protein, lipid, vitamin A and C as well as salt preference were associated with blood pressure in adolescents. It might be assumed that Ca lowered blood pressure by increasing serum Ca/Mg ratio and decreasing serum Ca/K ratio though urinary excretion of Na.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.38 no.3
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• pp.208-212
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• 1993

Since ramie suckers distribute soil surface layer within 10cm depth, some of them are dead from low soil temperature in winter. An experiment was conducted to investigate the effects of various mulching methods on safe overwintering of sucker at three or four years old, fully-grown ramie plots. The sprouting dates of ramie was March 28 in transparent vinyl mulching(TPEF), April 1 in transparent vinyl mulching over cover of straw, manure or rice hull at the amount of 500kg /10a (CM), and April 6 in black vinyl mulching(BDEF). These treatments showed earlier sprouting date from 9 to 18 days than the conventional mulching with 1000 kg straw /10a the sprouting date of which was April 15. TPEF treatment showed the earliest but ununiform sprouting. In contrast, sprouts in CM treatment was uniform but emerged somewhat later compared with the treatment of TPEF. The number of stems per unit area increased 50 percent more in TPEF, and 35 to 39 percent more in CM than the treatment of conventional mulching.