• Korean Journal of Soil Science and Fertilizer
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• v.26 no.3
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• pp.181-188
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• 1993

The effects of paddy-upland rotation and cropping system on the mineralization of soil organic nitrigen, on the change of organic matter and available phosphorus content in the soil, and on the rice yield and nutrients absorption were studied in Seokcheon fine-sandy loam soil. 1. In the incubation test mineralzed soil nitrogen and the nitrogen extracted by pH 7 phosphate buffer solutions were higher in the soils from every and two year rotation systems than continuous rice cultivation. In terms of cropping system potato-chiness cabbage-rice increased them more than soybean-rice system. 2. The change of soil organic matter and available phosphorus contents were not much in continuous rice cultivation, while in rotation system they decreased as the paddy-upland rotation frequency decreased. In terms of cropping system they decresed more in potato-Chinese cabbage-rice system compared with soybean-rice systems. 3. The rice yield was higher in the paddy-upland rotation system than that of continuous rice cultivation. However, the effects were decreased gradually every year, as shown by 26~20, 17~5, and 5~4% yield increase for first, second, and third year, respectively, in potato-Chinese cabbage-rice and soybean-rice system compared with continuous rice cultivation. 4. All the absorbed nutrient contents increased in every and two year rotation system compared with continuous rice cultivation. In terms of cropping system potato-Chiness cabbage-rice system increased them more compared with soybean-rice system.

• Korean Journal of Food Science and Technology
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• v.5 no.3
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• pp.183-187
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• 1973

Soong-Neung is a Korean traditional beverage served after meals and is made from Soong-Neung producing rice (Noo-Roon-Bap) which is cooked and toasted rice produced on the bottom of the container during the rice cooking process. In order to study the chemical changes occurring in Soong-Neung producing rice with temperature$(20{\sim}220^{\circ}C)$ during the cooking process, thermal analysis, total sugars, total nitrogen, reducing sugars, water soluble nitrogen, total acid, carbonyl content, phenolic compounds were determined. Thermal analysis showed that decrease of weight and endothermic reaction caused by evaporation of water in the sample appeared at $95{\sim}130^{\circ}C.$ The production of volatile compounds increased gradually beginning at $130^{\circ}C$, however, those compounds increased markedly at $160^{\circ}C$ and above. Maximum absorption of ultraviolet spectra of an aqueous distillate occurred at about $273m{\mu}$. Organoleptic analysis showed that an acceptable flavor was produced in the temperature range of $125{\sim}155^{\circ}C.$

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.4
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• pp.288-295
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• 2013

Nitrogen dioxide ($NO_2$) gas damage on vegetable crops commonly occurs in plastic film houses where relatively large amounts of $NO_3{^-}$ are applied in acid soils. In acid soils, $HNO_2$ can be formed from the $NO_2{^-}$ accumulated during denitrification, and $NO_2$ can be evolved from the chemical self-decomposition of $HNO_2$. In this study, $NO_2$ gas production and its detrimental effects on plants were investigated in soils of various conditions to elucidate the mechanisms involved in the gas production. A silty loam soil was amended with $NO_3{^-}$ (500 mg N $kg^{-1}$) and glucose, and pH and moisture of the soil were adjusted respectively to 5.0 and 34.6% water holding capacity (WHC) with 0.01 M phosphate buffer. The soil was placed in a 0.5-L glass jar with strawberry leaf or $NO_2$ gas absorption badge in air space of the jar, and the jar was incubated at $30^{\circ}C$. After 4-5 days of incubation, dark burning was observed along the outside edge of strawberry leaf and $NO_2$ production was confirmed in the air space of jar. However, when the soil was sterilized, $NO_2$ emission was minimal and any visible damage was not found in strawberry leaf. In the soil where water or $NO_3{^-}$ content was reduced to 17.3% WHC or 250 mg N $kg^{-1}$, $NO_2$ production was greatly reduced and toxicity symptom was not found in strawberry leaf. Also in the soil where glucose was not amended, $NO_2$ production was significantly reduced. In soil with pH of 6.5, $NO_2$ was evolved to the level causing damage to strawberry leaf when the soil conditions were favorable for denitrification. However, compared to the soil of pH 5.0, the $NO_2$ production and its damage to plants were much less serious in pH 6.5. Therefore, the production of $NO_2$ damaging plants might be occurred in acid soils when the conditions are favorable for denitrification.

• Korean Journal of Environmental Biology
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• v.32 no.3
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• pp.159-167
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• 2014

In this study, I examined the water quality and phytoplankton community in aquaculture laver farm in the southwest part of Aphae-do, South Korea, based on the young leaf stage, middle leaf stage, and adult leaf stage of laver thallus from October, 2013 to January, 2014. It was observed that the Aphae laver farm, as located in shallow waters, was found to have a serious resuspsension of the surface sediments due to physical disturbance caused by winds and tidal mixing. Such a resuspension of surface sediments coupled with nutrients supply obstructs light penetration into the sea for its huge amount of total suspended matters. As a result for this reason, it was viewed toimpedthe growth of phytoplankton was impeded as it also competes with laver to absorb the same kinds of nutrients as laver does during the laver growth period in winter. Such elements of the marine environment in Aphae laver farm are in contrast with the environment of Japan, where nutrients including dissolved inorganic nitrogen, in particular, are insufficient to cause the recent laver bad harvest, discoloration and quality degradation while large diatoms, with their higher nutrients absorption efficiency than laver, generate winter red tide. In other words, an important factor to maintain the high laver production in the southern parts of West Sea of Korea was found to be the marine environment of its laver farms where large diatoms are prevented from growing due to nutrients supply and dense seston weights from resuspended matters by physical disturbances.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.1
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• pp.21-28
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• 2018

The contents of total nitrogen, total phosphate, and total potash are important factors to determine the application rate of the organic fertilizers to arable lands. The concentrations of nutrient, organic matter, salt, water, heavy metal in mixed oil cakes and mixed organic fertilizers in circulation were investigated with 141 and 179, respectively. The mean levels of total nitrogen, total phosphate, and total potash in organic fertilizers of from 2015 to 2017 were 4.9%, 2.8%, 1.7%, respectively. The average contents of organic matter, salt, and water were 77.0%, 11.5%, and 0.3%, in mixed oil cakes, and 72.3%, 11.7%, 0.5% in mixed organic fertilizer, respectively. The maximum concentrations of Cr, Cu, Ni, and Zn were found to be in accordance with the official standard of commercial fertilizer. In order to promote balanced nutrient absorption of crops, it is necessary to increase the average content of total potash of the organic fertilizers to 3.2%.

• Applied Biological Chemistry
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• v.18 no.2
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• pp.65-70
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• 1975

The cultivation of ginseng plant (Panax ginseng C.A. Meyer) in Korea as an eminent medicinal herb may be traced far back in history. However, the practices in cultivation have not much improved in terms of efficiency and scientific farming. In the present study some experiments were undertaken for the search of the soil and nutrition conditions, because of the nutritional requirement of ginseng plant shaws quite unique compared with other crops. In both the seed bed and the field 'Yakto' has been traditionally employed or the prime source of nutrition of the crop. Yakto is a complex matter prepared from raw foliage of the broad-leaved trees as the main portion with the admixture of a variety of organic nitrogen source through fermentative processes. The composition of Yakto may be classified coarsely into the decomposed and undecomposed substances, the former being further fractionated according their solubilities, comprising also various colloidal matters whose composition and structure are yet to be known. The Yakto-fractions were subjected to analyze for search of its nature and coarse composition in terms of the distribution of nitrogen, contents of organic functional groups such as -COOH, phenolic-OH, alcholic-OH and methoxyl and hydrolysable sugars. Furthermore, absorption-spectra of each fraction were determined in visible and infrared region and compared the results each other.

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.4
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• pp.407-412
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• 1985

The effect of potash applied with different sources of nitrogen was experimented in pot soil culture on chinese cabbage (Brassica Pekinensis Rupr, Var. Fall 1984: Sammi Garak, Spring 1985: Jungang Summer lab.) in the fall, 1984 and in the spring, 1985. Results obtained are as follows; 1. Ammonium nitrate increased the yield of chinese cabbage more than urea did, and the effect of yield increase by ammonium nitrate was greater in the fall cultivation than in the spring. 2. The yield of chinese cabbage was positively correlated with the contents of K in the first (May 17, 1985) and second (June 9, 1985) thined cabbages (dry matter). It was also positively correlated with $NO_3-N$ content of the first thined cabbage and with K/Ca+Mg m.e, ratio of outer leaves of the harvested (June 27, 1985) cabbage, but negatively affected with Mg content of the outer leaves. 3. Correlations between K and $NO_3-N$ contained in the dry matter of first and second thined, and inner leaves of the harvested cabbage were learnt to be $r;0.9998^{**}$, r;0.4439, and $r;-0.7135^*$ respectively. The higher $NO_3-N$ content in the inner leaves of harvested cabbage was observed at K omitted ammonium nitrate plot where K was deficient, Ca and Mg contents were low. 4. The nutrient absorption and growth of chinese cabbage may take the following process. Nitrate nitrogen increases vegetative growth of the plant with enhanced K uptake and movement in to inner leaves and followed by replacement of Ca uptake and finally Mg uptake and its movement in to inner leaves.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.169-169
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• 2022

Over the past 100 years, the global average temperature has risen by 0.75 ℃. The Korean Peninsula has risen by 1.8 ℃, more than twice the global average. According to the RCP 8.5 scenario, the CO₂ concentration in 2100 will be 940 ppm, about twice as high as current. The National Institute of Crop Science(NICS) is using the SPAR (Soil-Plant Atmosphere Research) facility that can precisely control the environment, such as temperature, humidity, and CO₂. A Python-based colony photosynthesis algorithm has been developed, and the carbon and nitrogen absorption rate of rice is evaluated by setting climate change conditions. In this experiment, Oryza Sativa cv. Shindongjin were planted at the SPAR facility on June 10 and cultivated according to the standard cultivation method. The temperature and CO₂ settings are high temperature and high CO₂ (current temperature+4.7℃ temperature+4.7℃·CO₂ 800ppm), high temperature single condition (current temperature+4.7℃·CO₂ 400ppm) according to the RCP8.5 scenario, Current climate is set as (current temperature·CO₂400ppm). For colony photosynthesis measurement, a LI-820 CO₂ sensor was installed in each chamber for setting the CO₂ concentration and for measuring photosynthesis, respectively. The colony photosynthetic rate in the booting stage was greatest in a high temperature and CO₂ environment, and the higher the nitrogen fertilization level, the higher the colony photosynthetic rate tends to be. The amount of photosynthesis tended to decrease under high temperature. In the high temperature and high CO₂ environment, seed yields, the number of an ear, and 1000 seed weights tended to decrease compared to the current climate. The number of an ear also decreased under the high temperature. But yield tended to increase a little bit under the high temperature and high CO₂ condition than under the high temperature. In addition, In addition to this study, it seems necessary to comprehensively consider the relationship between colony photosynthetic ability, metabolite reaction, and rice yield according to climate change.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.3
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• pp.157-163
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• 2005

The increasing of greenhouse gases may change agricultural environment. The agronomic productivity will depend upon change of temperature, precipitation, solar radiation and fertilization. Particularly, nitrogen fertilization considerably influences rice productivity and agricultural environments. This experiment was conducted to study transformation of nitrogen and to determine the primary yield components responsible for yield differences in paddy soil. $NH_4-N$ concentration of NPK plot in surface water of paddy soil was $2.07mg\;L^{-1}$ at 5 days after transplanting, and then was decreased sharply due to rice absorption and loss to environment. $NO_3-N$ concentration of NPK plot in surface water was $3.97mg\;L^{-1}$ at 10 days after transplanting. $NO_3-N$ concentration range of CRF plot in surface water was $3-5mg\;L^{-1}$ at 30th after transplanting. The accumulation of $NH_3$ volatilization in NPK plot was $22.39kg\;ha^{-1}$, which accounted for 20% of N fertilizer applied but using of CRF fertilizer can reduce $NH_3$ volatilization by 67% in paddy soil. Use efficiency of N fertilizer was not different between CRF70% and CRF100% plot. Rate of N use efficiency were 27.4%, 51.2%, 49.0% in paddy field NPK, CRF70% and CRF100% plots respectively. The yield of CRF70% showed the best effect with 9.3% increase production ratio, compare with NPK plot.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.12
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• pp.907-912
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• 2011

Development of visible light responsive photocatalysts is a promising research area to facilitate utilization of solar energy for hydrogen production via photocatalytic water splitting. In this study two groups of samples, nitrogen (N)-doped niobium pentoxide ($Nb_2O_5$) and titanium dioxide ($TiO_2$) ($Nb_2O_5-N$, $HNb_3O_8-N$, $TiO_2-N$) and N-undoped ones ($Nb_2O_5$ and $TiO_2$) were tested. In order to utilize visible light, nitrogen atoms were doped in selected photocatalysts by using urea. A shift of the absorption edges of the Ndoped samples in the visible light region was observed. Under visible light irradiation, N-doped samples were more prominent photocatalytic activities than the N-undoped samples. Specifically, 99.7% of rhodamine B (RhB) was degraded after 60 minutes of visible light irradiation with $TiO_2-N$. Since $TiO_2-N$ shows the highest activity of RhB degradation, it was supposed to generate the highest current response. However, $HNb_3O_8-N$ showed the highest current response ($63.7mA/cm^2$) than $TiO_2-N$. More interestingly, when we compare the hydrogen production, $Nb_2O_5-N$ produced $19.4{\mu}mol/h$ of hydrogen.