• Korean Journal of Soil Science and Fertilizer
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• v.34 no.4
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• pp.292-301
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• 2001

The objectives of this study were to measure the changes in soil moisture regimes and the distribution patterns of inorganic N derived from the fertigated $^{15}N$-labeled urea, and compare them with the results obtained from broadcast-applied soil under the same drip irrigation domain. In fertigated soil, a $^{15}N$-labeled urea solution of $117mg\;N\;L^{-1}$ was applied by surface drip irrigation for 4 weeks. In broadcast-applied soil, no the other hand, 4 g of $^{15}N$-labeled urea(1.87 g N) mixed thoroughly with 5 kg of soil was placed on the surface of packed soil. Soil water status was controlled by drip irrigation scheduled at soil matric potential of -50 kPa. A calibrated time-domain reflectometry probe was installed in the soil vertically 15 cm apart from a drip emitter to control drip irrigation. About 60% of urea-derived inorganic nitrogen was remained in the top zone between 0 and 10 cm depth of fertigated soil, while, most of the inorganic nitrogen (91%) was accumulated in the top zone of broadcast-applied soil. Of inorganic nitrogen derived from urea, the percentage of $NO_3{^-}$ was much higher for fertigation (99%) than for surface application (62%). The relatively lower recovery of urea-derived inorganic nitrogen of broadcast-applied urea-N (51%) than that of fertigated urea-N (89%) was attributable to enhanced $NH_3$ volatilization.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.2
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• pp.137-141
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• 2002

Decomposition of green manure is necessary for the nutrient supply in farm soil. Hairy vetch as a green manure is superior to other winter legumes in terms of wintering ability and N accumulation. This experiment was carried out to investigate the decomposition and N release of hairy vetch and its effect on rice production as the following crop in paddy field. Decomposition of hairy vetch placed by soil depth of 0, 10 and 20cm at transplanting time was investigated by mesh bag method, which was enclosed chopped residue in mesh bags. The fate of $^{15}$ N derived from $^{15}$ N-labeled hairy vetch was investigated at harvest in three levels of N fertilization. Grain yield of the transplanted paddy rice cultured with hairy vetch as starter N were compared with that of applying urea as starter N in the field. Hairy vetch residue decomposed very rapidly both in transplanted and dry-seeded paddy field. In transplanted paddy field, hairy vetch residue lost 72-81 % and 86-90% of its weight after one and five month, respectively, as affected by incorporation depth. The C/N ratio of the decomposing vetch residue increased sharply during the early stages and after then, decreased slowly. The amounts of N and P released from the vetch were about 90% and 97% of initial content after one month, respectively. Recoveries of hairy vetch-$^{15}$ N by rice plant were 30.6, 34.6 and 35.7% in 0, 6 and 12 kg urea-N 10 $a^{-l}$ application, respectively, indicating that N fertilization increased the recovery of hairy vetch. $^{15}$ N. Hairy vetch residue incorporated as starter maintained significant N $H_4$$^{+}$-N concentration in soil water of plow layer until effective tillering stage. Grain yield in the plot applied with hairy vetch was not significantly different from that in the plot with urea. We concluded that hairy vetch incorporation could substitute starter N fertilization and showed possibility to reduce N amount of top-dressing.g.g.

• Korean Journal of Environmental Agriculture
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• v.28 no.3
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• pp.233-237
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• 2009

It has widely been observed that the effect of elevating atmospheric $CO_2$ concentrations on rice productivity depends largely on soil N availabilities. However, the responses of ammonia volatilization from flooded paddy soil that is an important pathway of N loss and thus affecting fertilizer N availability to concomitant increases in atmospheric $CO_2$ and temperature has rarely been studied. In this paper, we first report the interactive effect of elevated $CO_2$ and temperature on ammonia volatilization from rice paddy soils applied with urea. Urea labeled with $^{15}N$ was used to quantitatively estimate the contribution of applied urea-N to total ammonia volatilization. This study was conducted using Temperature Gradient Chambers (TGCs) with two $CO_2$ levels [ambient $CO_2$ (AC), 383 ppmv and elevated $CO_2$ (EC), 645 ppmv] as whole-plot treatment (main treatment) and two temperature levels [ambient temperature (AT), $25.7^{\circ}C$ and elevated temperature (ET), $27.8^{\circ}C$] as split-plot treatments (sub-treatment) with triplicates. Elevated temperature increased ammonia volatilization probably due to a shift of chemical equilibrium toward $NH_3$ production via enhanced hydrolysis of urea to $NH_3$ of which rate is dependent on temperature. Meanwhile, elevated $CO_2$ decreased ammonia volatilization and that could be attributed to increased rhizosphere biomass that assimilates $NH_4^+$ otherwise being lost via volatilization. Such opposite effects of elevated temperature and $CO_2$ resulted in the accumulated amount of ammonia volatilization in the order of ACET>ACAT>ECET>ECAT. The pattern of ammonia volatilization from applied urea-$^{15}N$ as affected by treatments was very similar to that of total ammonia volatilization. Our results suggest that elevated $CO_2$ has the potential to decrease ammonia volatilization from paddy soils applied with urea, but the effect could partially be offset when air temperature rises concomitantly.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.6
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• pp.376-383
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• 2003

To utilize composts more efficiently, combining composts with fertilizer to meet crop requirements is an appealing alternative. A pot experiment was conducted to study the effect of application rate of composted pig manure blended with fertilizer on the availability and loss of fertilizer-N. Chinese cabbage (Brassica campestris L. cv. Samjin) plants were cultivated for 30 and 60 days. 15N-Labeled urea ($5.24\;^{15}N\;atom\;%$) was added to soil at $450mg\;N\;kg^{-1}$, and unlabeled compost ($0.37\;^{15}N\;atom\;%$) was added at 0, 200, 400, and $600mg\;N\;kg^{-1}$. The amount of plant-N derived from urea was not affected by compost application at rate of $200mg\;N\;kg^{-1}$. However, compost application at 400 and $600mg\;N\;kg^{-1}$ significantly (P<0.05) increased plant assimilation of N from urea irrespective of sampling time, probably because of physicochemical changes in the soil properties allowing urea-N to be assimilated more efficiently. The amount of immobilized urea-N increased with increasing rate of compost application at both growth periods, as the results of increased microbial activities using organic C in the compost. Total recovery of urea-N (as percentage of added N) by Chinese cabbage and soil also increased with increasing rate of compost from 71.5 to 95.6% and from 67.0 to 88.2% at the 30- and 60-days of growth, respectively. These results suggest that increasing rate of compost blending increases plant uptake of fertilizer-N and enhances immobilization of fertilizer-N, which leads to decrease in loss of fertilizer-N. However, information about the fate of immobilized N during future crop cultivation is necessary to verify long-term effect of compost blending.

• Applied Biological Chemistry
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• v.37 no.4
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• pp.277-286
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• 1994

The pot experiment using $^{15}N$ isotope dilution technique was carried out to calculate the balance of nitrogen of surface applied urea in the rice-soil system. The $^{15}N$ concentration was determined by stable isotope ratio mass spcetrometer (model: VG ISO-GAS MM622). In the pots with $^{15}N$ labeled urea application at the rates of 15 and 30 kg N/10a, the percentage of nitrogen derived from fertilizer (NDFF) in rice was higher at the rate of 30 kg N/10a (average 89%) than at the rate of 15 kg N/10a (average 64%). However, the recovery as percentage of fertilizer N by rice was higher at the rate of 15 kg N/10a (65.5%) than at the rate of 30 kg N/10a (54.2%). The percentage of the fertilizer N remained in extractable inorganic N form at the rates of 15 and 30 kg N/10a were $13.5%\;(NH_4-N\;5.53%,\;NO_3-N\;7.99%)$ and $16.5%\;(NH_4-N\;7.49%,\;NO_3-N\;8.98%)$ in unplanted soil, and $2.0%\;(NH_4-N\;0.63%,\;NO_3-N\;1.32%)$ and$2.3%\;(NH_4-N\;0.87%,\;NO_3-N\;1.40%)$ in soil planted to rice, respectively. The dominant form of inorganic-N in soil after harvest was $NO_3-N$ form rather than $NH_4-N$ form regardless of urea application rate or rice cultivation. The percentage of the fertilizer N remained in organic N form at the rates of 15 and 30 kg N/10a were 65.0 and 41.8% in unplanted soil, and 23.7 and 26.9% in soil planted to rice, respectively. In conclusion, the efficiency of surface-applied urea was greater at the rate 15 kg N/10a than at the rate of 30 kg N/10a.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.3
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• pp.457-466
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• 2018

Objective: The present study aimed to assess the nitrogen (N) use efficiency of acidified pig slurry for regrowth yield and its environmental impacts on perennial ryegrass swards. Methods: The pH of digested pig slurry was adjusted to 5.0 or 7.0 by the addition of sulfuric acid and untreated as a control. The pig slurry urea of each treatment was labeled with $^{15}N$ urea and applied at a rate of 200 kg N/ha immediately after cutting. Soil and herbage samples were collected at 7, 14, and 56 d of regrowth. The flux of pig slurry-N to regrowth yield and soil N mineralization were analyzed, and N losses via $NH_3$, $N_2O$ emission and $NO_3{^-}$ leaching were also estimated. Results: The pH level of the applied slurry did not have a significant effect on herbage yield or N content of herbage at the end of regrowth, whereas the amount of N derived from pig slurry urea (NdfSU) was higher in both herbage and soils in pH-controlled plots. The $NH_4{^+}-N$ content and the amount of N derived from slurry urea into soil $NH_4{^+}$ fraction ($NdfSU-NH_4{^+}$) was significantly higher in in the pH 5 plot, whereas $NO_3{^-}$ and $NdfSU-NO_3{^-}$ were lower than in control plots over the entire regrowth period. Nitrification of $NH_4{^+}-N$ was delayed in soil amended with acidified slurry. Compared to non-pH-controlled pig slurry (i.e. control plots), application of acidified slurry reduced $NH_3$ emissions by 78.1%, $N_2O$ emissions by 78.9% and $NO_3{^-}$ leaching by 17.81% over the course of the experiment. Conclusion: Our results suggest that pig slurry acidification may represent an effective means of minimizing hazardous environmental impacts without depressing regrowth yield.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.2
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• pp.132-139
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• 1999

A field experiment was conducted at Cheju from early March 1998 to early March 1999 to evaluate the effects of foliar applied urea on leaf N content and N recovery in satsuma mandarins (Citrus unshiu Marc.). Seven years old 'Okitsu Wase' trees received foliar spray of urea (22 or 43 g N $tree^{-1}yr^{-1}$) or soil application of urea (86 g N $tree^{-1}yr^{-1}$). 56% of N was applied in spring, 11% in summer and 33% in fall. There were seven trees per N treatment and two trees per N treatment received $^{15}N$-labeled urea in spring and summer to determine N recovery. There were no differences between the treatments for fruit yield and its quality. Nitrogen content of spring flush leaf blades up to early September was greater for trees received foliar spray comparing with soil application but was not greatly affected by any treatment after mid-November. The recovery of fertilizer N in various parts of trees receiving foliar spray of 22 g N $tree^{-1}yr^{-1}$ was greatest, followed by receiving foliar spray of 43 g N and soil application of 86 g N. The recovery of fertilizer N in tree was 29.2 and 17.7% for foliar spray of 22 and 43 g N $tree^{-1}yr^{-1}$, respectively and 8.0% for soil application of 86 g N $tree^{-1}yr^{-1}$. The recovery of fertilizer N in the upper 40 cm of soil was 50.3, 45.6, and 51.8% for foliar spray of 22 and 43 g N $tree^{-1}yr^{-1}$, and soil application of 86 g N $tree^{-1}yr^{-1}$ respectively. The total (tree, fallen leaves, winter weeds, and soil) recovery of fertilizer N was 81.8, 65.1, and 60.6% for foliar spray of 22 and 43 g N $tree^{-1}yr^{-1}$, and soil application of 86 g N $tree^{-1}yr^{-1}$, respectively.

• Journal of the Korean Magnetic Resonance Society
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• v.16 no.1
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• pp.34-45
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• 2012

Melanocortin-4 receptor (MC4R) subtype is associated with obese humans. Especially, in a patient with severe early-onset obesity, novel heterozygous mutation in the MC4R gene was detected, resulting in an exchange of aspartic acid to asparagine in $90^{th}$ amino acid residue located in the predicted second trans-membrane domain (TM2). Mutations in the melanocortin-4 receptor (MC4R) gene are the most frequent monogenic causes of severe obesity which have been described as heterozygous with loss of function. In order to compare structure difference between MC4R wild type (MC4R-TM2-wt) and mutant (MC4R-TM2-D90N), we designed both MC4R-TM2-wt and MC4R-TM2-D90N construct in pET 21b vector. In this study, we optimized high-yield purification procedure for recombinant TM2-D90N. Eluted recombinant protein was resolubilized under urea condition for thrombin cleavage reaction and we conducted the high-performance liquid chromatography (HPLC) with reverse phase column under 1% acetonitrile, 0.01% TFA buffer solution. The molecular size of purified target peptide was confirmed by Tricine-SDS page analysis. To characterize MC4R-TM2-D90N, we have performed $^{15}N$-isotope labeling of peptide using M9 media and purified labeled target peptide for hetero-nuclear NMR spectroscopy.

• Applied Biological Chemistry
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• v.25 no.4
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• pp.232-238
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• 1982

From ^{15}N$ labelled nitrogen experiments on 13 fields use efficiency by difference method was higher than that by labelling method in 80% of fields tested indicating augmentation of soil nitrogen uptake by fertilizer nitrogen. Both methods showed very similar trend among fields. Sulfur coated urea(SCU) and point application increased fertilization efficiency(yield increment per fertilizer nitrogen applied, Fe) to 23 from 15 of split application through the increase of fertilizer use efficiency from 29(Eu) to 50 but tended to decrease efficiency of absorbed fertilizer nitrogen(yield increment per nitrogen derived from fertilizer, Ef) from 50. to 46 High yielding capacity of Tongil line appears to be attributed to the higher Ef, translocation efficiency and soil nitrogen preference index(soil nitrogen increment in plant per the increment of fertilizer nitrogen in plant, PI). This studies confirmed that yield under fertilizer application system depends on Fe which is the multiplication of Eu and Ef and that the improvement of fertilizer management(form, application method and time) increases principally Eu, the limit of which is controlled by Ef that is attributed mainly to varietal characteristics.