• Journal of Biosystems Engineering
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• 제42권2호
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• pp.98-103
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• 2017

Purpose: Precision agriculture includes determining the right amount of nitrogen for a specific location in the field. This work focused on developing and validating a model using variable rate nitrogen application based on the estimated SPAD value from the ground-based image sensor. Methods: A variable rate N application based on the decision making system was performed using a sensor-based variable rate nitrogen application system. To validate the nitrogen application decision making system based on the SPAD values, the developed N recommendation was compared with another conventional N recommendation. Results: Sensor-based variable rate nitrogen application was performed. The nitrogen deficiency level was measured using the image sensor system. Then, a variable rate application was run using the decision model and real-ti me control. Conclusions: These results would be useful for nitrogen management of corn in the field. The developed nitrogen application decision making system worked well, when considering the SPAD value estimation.

• Journal of Biosystems Engineering
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• 제35권2호
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• pp.132-137
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• 2010

Site-specific N application for corn is one of the precision crop management. To implement the site-specific N application, various nitrogen stress sensing methods, including aerial image, tissue analysis, soil sampling analysis, and SPAD meter readings, have been used. Use of side-dressing, an efficient nitrogen application method than a uniform application in either late fall or early spring, relies mainly on the capability of nitrogen deficiency detection. This paper presents map-based variable rate nitrogen application based using a multi-spectral corn nitrogen deficiency(CND) sensor. This sensor assess the nitrogen stress by means of the estimated SPAD reading calculated from the corn leave reflectance. The estimated SPAD value from the CND sensor system and location information form DGPS of each field block was combined into the field map using a ArcView program. Then this map was converted into a raster file for a map-based variable rate application software. The relative SPAD (RSPAD = SPAD over reference SPAD) was investigated 2 weeks after the treatments. The results showed that the map-based variable rate application system was feasible.

• Journal of The Korean Society of Grassland and Forage Science
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• 제15권2호
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• pp.93-100
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• 1995

This experiment was carried out to investigate how to effect the application of nitrogen, phosphate and potassium on the vegetation and dry matter yield in the mixed sward of orchardgrass and crabgrass (Digitaria sanguinalis [L.] Scop.). The experimental sward wa5 consisted of eight plots of non-application, P, K, PK, N. NK, NP and NPK. These plots were sown with seeds mixture of orchardgrass 17.5 kglha and crabgrass 17.5 kg/ ha on 22 April 1975 in the forage experimental field of Kangwon National University, Chunchon, Korea, and were cut four times from 6 July to 18 November 1975. The results obtained were summarized as follows: 1. In orchardgrass density measured after summering, the plot of nitrogen applied without phosphate marked only 3 1.0% of the plot of nitrogen applied with phosphate while in crabgrass density measured at that time the plot of nitrogen applied without phosphate marked as high as 112.5% of the plot of nitrogen applied with phosphate. 2. Application of phosphate and potassium improved wintering record of orchardgrass. In orchardgrass density measured after wintering, the plot of nitrogen applied without phosphate marked only 9.7% of the plot of nitrogen applied with phosphate, and the plot of NP applied without K marked 63.6% of the plot of NP applied with K. 3. In surface coverage of orchardgrass, in midsummer any plot applied with nitrogen regardless of accompanying with or not with phosphate wa5 0%, but in autumn the plot of nitrogen applied with phosphate was 56-58% and the plot of nitrogen applied without phosphate was 5%. While after wintering the plot of nitrogen applied with phosphate was 28-37% though the plot of nitrogen applied without phosphate was only 0.3-0.6%; the application of phosphate improved summering and wintering record of orchardgrass. 4. Application of phosphate demonstrated remarkable effect on increasing dry matter yield in orchardgrass. In year total yield of orchardgrass, the plot of nitrogen applied without phosphate marked as low as 11.3% of the plot of nitrogen applied with phosphate, but in crabgrass the plot of nitrogen applied without phosphate was almost equal to the plot of nitrogen applied with phosphate showing 97.5% of this plot. 5. Application of potassium was not effective on increasing dry matter yield of orchardgrass but its application was effective on increasing dry matter yield of crabgrass. In dry matter yield of orchardgrass significant difference was not found between NP plot and NPK plot, but in dry matter yield of crabgrass NPK plot recorded significantly higher yield compared with NP plot (p<0.05). 6. In botanical composition of the plot of nitrogen applied with phosphate, crabgrass recorded 46.5-50.5% in early summer (July) but in midsummer (August) it dominated the plot recording 85.6-91.2%. 7. In botanical composition based on the year total yield, in the plot of nitrogen applied with phosphate orchardgrass marked 21.7-26.2% and crabgrass recorded 73.8-78.370, but in the plot of nitrogen applied without phosphate orchardgrass marked only 3.5% being overwhelmingly dominated by crabgrass which recorded 96.5%. 8. Application of nitrogen not accompanied with phosphate strengthened competitive power of the crabgrass unilaterally, making orchardgrass be oppressed fatally by the crabgrass.

• Journal of Biosystems Engineering
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• 제28권4호
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• pp.361-368
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• 2003

This study was intended to investigate the temporal and spatial variabilities of dry matter, nitrogen content, chlorophyll of paddy rice and yield caused by different rates of nitrogen application. An experimental field was divided into 45 plots of 3.48 ${\times}$ 12 m in size and application rate of nitrogen varied from 0 to 235% with an increment of 25% based on the standard rate of N-P$_2$O$_{5}$-K$_2$O=12-8-8 kg/10a. The measurements were made 8 times every 9-10 days after the transplanting. About 60 days after the transplanting, there exhibited little variabilities in the dry matter caused by different rates of nitrogen application. After that. however, there showed large variabilities and the dry matter increased with the application rate. The nitrogen content of paddy also increased with the application rate but it was inconsistent. After the tillering period, the nitrogen content remained constant. In the early stage of the tillering period the nitrogen content decreased in spite of increase in the dry matter. However. after a certain period of time it increased with the dry matter. There were little variabilities of chlorophyll after the transplanting. However, the SPAD increased with application rate of nitrogen as the paddy grew. After the tillering period SPAD was not affected by the different rates. More yield was obtained at the plots where larger nitrogen content was measured.d.

• Korean Journal of Environmental Agriculture
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• 제29권1호
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• pp.33-38
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• 2010

To improve the existing nitrogen recommendation method based on chemical properties of soils and to establish new recommendation rates of nitrogen fertilizer due to different types of soils, the application rates of nitrogen fertilizer were examined in different soils of 12 experimental rice paddy fields. The application rates of nitrogen fertilizer estimated by soil-testing were higher than the rates of nitrogen standard recommendation that has been used. The application rates for minimum rice productivity ranged from a low of 168 kg/10a in sandy soil to a high of 315 kg/10a in saline soil. Amounts of nitrogen absorption in rice were proportional to the application amounts of nitrogen fertilizer in soils. Nitrogen use efficiency was the highest, 36.7%, in immatured paddy field and it was inversely proportional to the application amounts of nitrogen. the rice tasty value was the highest in the soils without nitrogen application, and also it was the lowest in the saline soils with or without nitrogen application. As comparing with the nitrogen application rates obtained by the existing nitrogen recommendation method, optimal nitrogen application rates estimated by the standardization of nitrogen application efficiency rate, environmental index, and rice quality were 1.0 fold in the well adapted soil and sandy soil fields, 0.92 fold in the immatured soil field, and 0.83 fold in the saline soil field.

• Korean Journal of Medicinal Crop Science
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• 제17권5호
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• pp.363-368
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• 2009

To fulfill the increasing demand for a high quality of flower, we investigated the effects of nitrogen application on plant growth, yield and bioactive compounds of Chrysanthemum indicum L.. C. indicum L. was cultivated in a pot scale, and nitrogen applied with the level of 0 (N0), 50 (N50), 100 (N100), 150 (N150), 200 (N200) and $300\;(N300)\;kg\;ha^{-1}$ to suggest optimum rate of nitrogen fertilization. Phosphate and potassium applied the same amount of $80-80\;kg\;ha^{-1}$ ($P_2O_5-K_2O$) in all treatments. Growth characteristics and yields of C. indicum L. were significantly affected by nitrogen application. Maximum yield achieved in 265 and $295\;kg\;ha^{-1}$ N treatment on the whole plant and the flower parts, respectively. The nitrogen content and uptake of whole plant significantly increased by the increase of nitrogen application. Five major components of essential oil, $\alpha$-pinene, 1,8-cineol, chrysanthenone, germacrene-D, and $\alpha$-curcumene in flowerheads of C. indicum L. occupied approximately 40% of peak area, germacrene-D decreased by the increase of nitrogen application among them. However, cumambrin A contents in the flower parts of C. indicum L. were affected negatively by the increase of nitrogen application, but total yields of cumambrin A in flower part significantly increased. Conclusively, nitrogen fertilization could increase the yield of flowerheads. The optimum application level of nitrogen fertilizer might be on the range of $265-295\;kg\;ha^{-1}$ in a mountainous soil.

• KOREAN JOURNAL OF CROP SCIENCE
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• 제21권2호
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• pp.269-276
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• 1976

This experiment was conducted to find out how to increase efficiency of fertilizer nitrogen and how to change the weed population with different methods of nitrogen application. Mudball deep placement, at 10-12cm soil depth, produced significantly the highest grain yield within the application methods with same amount of nitrogen (60kg N/ha). It produced also same grain yield with conventional application methods, timely split application method, with 90kg N/ha. Basal application of nitrogen increased weed population and it showed higher dry weight of weed than top dressing methods at early growth stage of rice.

• KOREAN JOURNAL OF CROP SCIENCE
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• 제45권4호
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• pp.237-240
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• 2000

This experiment was conducted to evaluate the effect of split application of nitrogen(N) on development of vascular bundle(VB) and yield components of rice. Two cultivars were used in this study; IR58, an indica type and Shinunbongbyeim a japonica type. The number and total cross sectional area of the VB in the peduncle and leaf blade were more and bigger in N split application than 100 percent basal fertilizer. Nitrogen split application at necknode differentiation stage increased the number and size of the VB. Nitrogen split application resulted in increased panicle number with application of N before transplanting and at tillering stage; increased spikelets number with N application at necknode differentiation stage; and increased spikelet fertility and 1000 grain weight with N application at necknode differentiation and heading stages. Grain yield increased 7-10% in N split as compared to all basal application. The total cross sectional area of VB in peduncle closely correlated with the number of spikelets per panicle. Nitrogen management can have an impact on spikelet differentiation through more and bigger VB and increase grain yield potential.

• KOREAN JOURNAL OF CROP SCIENCE
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• 제22권2호
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• pp.42-47
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• 1977

Experiment was conducted to find out the influence of nitrogen and potassium split application on the yield and physiology of rice plants in a sandy-gravel soil. Nitrogen and potassium mixed application, nitrogen split application, and potassium split application increased yield of rice by 22, 20, and 18%, respectively, compared to conventional fertilizer application. Nitrogen split application increased chlorophyll content and potassium split application increased root activity. Concentration of silica, magnesium, and calcium was increased by the mixed split application of nitrogen and potassium.

• Journal of The Korean Society of Grassland and Forage Science
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• 제20권2호
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• pp.131-138
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• 2000

This experiment was carried out during the period from September, 1997 to October, 1998 to determine the effect of fermented saw-dust pig manure (FSP) application on the herbage production on a mixed pasture in the Cheju brown volcanic ash soil. Split plot design (main plot: 3 nitrogen application levels of 0, 150 and 300 kgiha; sub plot: 4 pig sawdust manure levels of 0, 3, 6 and 12 tonha) was used. Plant height and dry matter yield increased significantly with an increase of nitrogen and FSP level. There was no difference in the botanical composition of grasses as affected by FSP application level, but herbage yields of grass species were increased by nitrogen application compared to that without nitrogen application. Botanical composition of white clover decreased with an increase of nitrogen application, but increased with an increase of FSP application level. Percentages of weeds were not affected by application rates of chemical nitrogen fertilizer and swine manure in the mixed species pasture. Nitrogen, phosphorus, and potassium contents of species in the pasture significantly increased with increasing application rates of nitrogen fertilizer. In conclusion, it would be an optimum to apply 150 kgha of inorganic chemical fertilizer and plus either 3 or 6 toniha of fermented swine manure with sawdust for optimum production of mixed pasture on Cheju Island. (Key words : Herbage production, Botanical composition, Morphology, Plant mineral contents)