• Title/Summary/Keyword: field coefficient

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Yearly Variation of Ecological Traits of Weed Flora on Soils Having Different Drainage Property (배수불량 농경지에서 토양수분별 연차간 잡초발생 군락 특성)

  • Hwang, Jae-Bok;Yun, Eul-Soo;Jung, Ki-Youl;Park, Chang-Young;Choi, Young-Dae;Lee, Yong-Hwan;Nam, Min-Hee
    • Korean Journal of Weed Science
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    • v.31 no.1
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    • pp.41-48
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    • 2011
  • This survey of weed population by different soil moisture with paddy-upland rotation was conducted to investigate information on weed flora and its ecology between two years. Weed species were assessed in April : 2009, 2010. Soil samples were taken from each study plot to assess the impact soil moisture on the occurrence and abundance of dominance weed species. Soil water of poorly drained field ranged from 10.2~18.2% more than 11.8~14.3% of somewhat poorly drained field. Weeds of fields composed of 19 species belonging to 12 families. Among 12 families, 6 weed species belonged to Compositae (31.6%) were the biggest family, Cruciferae were 2 species (10.5%), and Rubiaceae were 2 species (10.5%), respectively. Youngia japonica had the highest summed dominance ratio(SDR) (97.0%) and followed by Conyza canadensis (92.1%), Galium spurium (35.3%) and Hemistepta lyrata (28.4%) of somewhat poorly drainage in 2009. Artemisia princeps the highest SDR (100%) and followed by Stellaria alsine(55.2%), Y. japonica (38.3%) and Nasturtium officinale (28.5%) of poorly drainage in 2009. And, Stellaria alsine had the highest SDR (86.8%) and followed by Alopecurus aequalis (77.7%), Astragalus sinicus (68.7%) and Y. japonica (46.3%) of somewhat poorly drainage in 2010. S. alsine the highest SDR (93.7%) and followed by A. aequalis (78.6%), Nasturtium officinale (31.3%) and Y. japonica (30.4%) of poorly drainage in 2010. Simpson's index was calculated to 0.12~0.23, which showed that weed occurrence with different soil moisture in paddy-upland rotation and between years was various. Similarity coefficient between years was 43.0% (2009) and 74.2% (2010), which indicate a low diversity because of the moisture in the agro-ecosystem.

Modified Traditional Calibration Method of CRNP for Improving Soil Moisture Estimation (산악지형에서의 CRNP를 이용한 토양 수분 측정 개선을 위한 새로운 중성자 강도 교정 방법 검증 및 평가)

  • Cho, Seongkeun;Nguyen, Hoang Hai;Jeong, Jaehwan;Oh, Seungcheol;Choi, Minha
    • Korean Journal of Remote Sensing
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    • v.35 no.5_1
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    • pp.665-679
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    • 2019
  • Mesoscale soil moisture measurement from the promising Cosmic-Ray Neutron Probe (CRNP) is expected to bridge the gap between large scale microwave remote sensing and point-based in-situ soil moisture observations. Traditional calibration based on $N_0$ method is used to convert neutron intensity measured at the CRNP to field scale soil moisture. However, the static calibration parameter $N_0$ used in traditional technique is insufficient to quantify long term soil moisture variation and easily influenced by different time-variant factors, contributing to the high uncertainties in CRNP soil moisture product. Consequently, in this study, we proposed a modified traditional calibration method, so-called Dynamic-$N_0$ method, which take into account the temporal variation of $N_0$ to improve the CRNP based soil moisture estimation. In particular, a nonlinear regression method has been developed to directly estimate the time series of $N_0$ data from the corrected neutron intensity. The $N_0$ time series were then reapplied to generate the soil moisture. We evaluated the performance of Dynamic-$N_0$ method for soil moisture estimation compared with the traditional one by using a weighted in-situ soil moisture product. The results indicated that Dynamic-$N_0$ method outperformed the traditional calibration technique, where correlation coefficient increased from 0.70 to 0.72 and RMSE and bias reduced from 0.036 to 0.026 and -0.006 to $-0.001m^3m^{-3}$. Superior performance of the Dynamic-$N_0$ calibration method revealed that the temporal variability of $N_0$ was caused by hydrogen pools surrounding the CRNP. Although several uncertainty sources contributed to the variation of $N_0$ were not fully identified, this proposed calibration method gave a new insight to improve field scale soil moisture estimation from the CRNP.

Detection of Pine Wilt Disease tree Using High Resolution Aerial Photographs - A Case Study of Kangwon National University Research Forest - (시계열 고해상도 항공영상을 이용한 소나무재선충병 감염목 탐지 - 강원대학교 학술림 일원을 대상으로 -)

  • PARK, Jeong-Mook;CHOI, In-Gyu;LEE, Jung-Soo
    • Journal of the Korean Association of Geographic Information Studies
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    • v.22 no.2
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    • pp.36-49
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    • 2019
  • The objectives of this study were to extract "Field Survey Based Infection Tree of Pine Wilt Disease(FSB_ITPWD)" and "Object Classification Based Infection Tree of Pine Wilt Disease(OCB_ITPWD)" from the Research Forest at Kangwon National University, and evaluate the spatial distribution characteristics and occurrence intensity of wood infested by pine wood nematode. It was found that the OCB optimum weights (OCB) were 11 for Scale, 0.1 for Shape, 0.9 for Color, 0.9 for Compactness, and 0.1 for Smoothness. The overall classification accuracy was approximately 94%, and the Kappa coefficient was 0.85, which was very high. OCB_ITPWD area is approximately 2.4ha, which is approximately 0.05% of the total area. When the stand structure, distribution characteristics, and topographic and geographic factors of OCB_ITPWD and those of FSB_ITPWD were compared, age class IV was the most abundant age class in FSB_ITPWD (approximately 55%) and OCB_ITPWD (approximately 44%) - the latter was 11% lower than the former. The diameter at breast heigh (DBH at 1.2m from the ground) results showed that (below 14cm) and (below 28cm) DBH trees were the majority (approximately 93%) in OCB_ITPWD, while medium and (more then 30cm) DBH trees were the majority (approximately 87%) in FSB_ITPWD, indicating different DBH distribution. On the other hand, the elevation distribution rate of OCB_ITPWD was mostly between 401 and 500m (approximately 30%), while that of FSB_ITPWD was mostly between 301 and 400m (approximately 45%). Additionally, the accessibility from the forest road was the highest at "100m or less" for both OCB_ITPWD (24%) and FSB_ITPWD (31%), indicating that more trees were infected when a stand was closer to a forest road with higher accessibility. OCB_ITPWD hotspots were 31 and 32 compartments, and it was highly distributed in areas with a higher age class and a higher DBH class.

A Study on the Reinforcement Effect Analysis of Aging Reservoir using Grout Material recycled Power Plant Byproduct (발전부산물을 재활용한 그라우트재의 노후 저수지 보강효과 분석에 관한 연구)

  • Seo, Se-Gwan;An, Jong-Hwan;Cho, Dae-sung
    • Journal of the Korean Geosynthetics Society
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    • v.20 no.2
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    • pp.23-33
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    • 2021
  • In Korea, many reservoirs have been built for the purpose of solving the food shortage problem and supplying agricultural water. However, the current 75.6% of the reservoirs are in serious aged as more than 50 years have passed since the year of construction. In the case of such an aging reservoir, the stability due to scour and erosion inside the reservoir is very reduced, and if concentrated rainfall due to recent abnormal weather occurs, the aging reservoir may collapse, leading to a lot of damage to property and human life. Accordingly, each agency that manages aging reservoirs uses Ordinary Portland Cement (OPC) as an injection material and applies the grouting method. However, in the case of OPC, it may deteriorate over time and water leakage may occur again. And there are environmental problems such as consumption of natural resources and generation of greenhouse gases. So, there is a need to develop new materials and methods that can replace the OPC. In this study, an laboratory test and analysis were performed on the grout material developed to induce a curing reaction similar to that of OPC by recycling power plant byproduct. In addition, test in the field such as electric resistivity survey, Standard Penetration Test (SPT), and field permeability test were performed to analyzed to reinforcement effect and determine the possibility of using instead of OPC. As a results of the test, in the case of recycled power plant byproduct, the compressive strength was 2.9 to 3.2 times and the deformation modulus was 2.3 to 3.3 times higher, indicating that it is excellent in strength and can be used instead of OPC. And it was analyzed that the N value of the reservoir was increased by 1~2, and the coefficient of permeability (k) decreased to the level of 8.9~42.5%. showing sufficient reinforcing effect in terms of order.

A stratified random sampling design for paddy fields: Optimized stratification and sample allocation for effective spatial modeling and mapping of the impact of climate changes on agricultural system in Korea (농지 공간격자 자료의 층화랜덤샘플링: 농업시스템 기후변화 영향 공간모델링을 위한 국내 농지 최적 층화 및 샘플 수 최적화 연구)

  • Minyoung Lee;Yongeun Kim;Jinsol Hong;Kijong Cho
    • Korean Journal of Environmental Biology
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    • v.39 no.4
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    • pp.526-535
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    • 2021
  • Spatial sampling design plays an important role in GIS-based modeling studies because it increases modeling efficiency while reducing the cost of sampling. In the field of agricultural systems, research demand for high-resolution spatial databased modeling to predict and evaluate climate change impacts is growing rapidly. Accordingly, the need and importance of spatial sampling design are increasing. The purpose of this study was to design spatial sampling of paddy fields (11,386 grids with 1 km spatial resolution) in Korea for use in agricultural spatial modeling. A stratified random sampling design was developed and applied in 2030s, 2050s, and 2080s under two RCP scenarios of 4.5 and 8.5. Twenty-five weather and four soil characteristics were used as stratification variables. Stratification and sample allocation were optimized to ensure minimum sample size under given precision constraints for 16 target variables such as crop yield, greenhouse gas emission, and pest distribution. Precision and accuracy of the sampling were evaluated through sampling simulations based on coefficient of variation (CV) and relative bias, respectively. As a result, the paddy field could be optimized in the range of 5 to 21 strata and 46 to 69 samples. Evaluation results showed that target variables were within precision constraints (CV<0.05 except for crop yield) with low bias values (below 3%). These results can contribute to reducing sampling cost and computation time while having high predictive power. It is expected to be widely used as a representative sample grid in various agriculture spatial modeling studies.

Variations in subtidal surface currents observed with HF radar in the costal waters off the Saemangeum areas (새만금 연안역에서 HF radar에 의해 관측된 조하주기 표층해류의 변화)

  • Kim, Chang-Soo;Lee, Sang-Ho;Son, Young-Tae;Kwon, Hyo-Keun;Lee, Kwang-Hee;Choi, Byoung-Hy
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.13 no.1
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    • pp.56-66
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    • 2008
  • Subtidal surface currents are derived from HF radar measurements in the Saemangeum coastal ocean of the Yellow sea in July 2002 and from September to November 2004. The surface current field is analyzed to examine the effect of wind, river plume and coastline change on the spatial distribution and temporal variation of the surface currents. In July 2002, average wind speed was 0.5 m/s and freshwater discharge from the Keum River was $0.88{\times}10^7\;ton/day$. Temporal mean currents ($\overline{U}$) flow to the northwest with speed of $7{\sim}10\;cm/s$ near the Keum River estuary, to the west as fast as 13 cm/s near the opening gap of the Saemangeum $4^{th}$ dyke, and to the northwest off the Gogunsan-archipelago. This flow pattern is a result of the Keum River plume dispersal and tide-residual currents from the opening gap of the Saemangeum $4^{th}$ dyke. Time series of spatially-averaged current (<$U-\overline{U}$>) direction is highly (r=0.98) correlated with wind direction. From September to November 2004, the opening gap of the Saemangeum $4^{th}$ dyke was closed, northwesterly wind blew with speed of 2.5 m/s on average and the Keum River discharge was $1.19{\times}10^7\;ton/day$. Temporal mean current field ($\overline{U}$) has weak surface flow in most of the coastal ocean and relatively strong currents flow to the southwest with speed of 10 cm/s along the shape coastline of the Gogunsan-archipelago and the Saemangeum $4^{th}$ dyke. The strong flow is generated by the prevailing northwesterly wind which pushes the Keum River plume toward the Saemangeum $4^{th}$ dyke. The residual currents from the opening gap of the Saemangeum $4^{th}$ dyke disappeared and correlation coefficient between time series of spatially-averaged current () direction and the wind direction is 0.69.

Studies on the Inheritance of Heading Date in Wheat(Triticum aestivum L. em Thell) (소맥(Triticum aestivum L. em Thell)의 출수기 유전에 관한 연구)

  • Chang-Hwan Cho
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.15
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    • pp.1-31
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    • 1974
  • Introducing genes for earliness of wheat varieties is important to develop early varieties in winter wheat. In oder to obtain basic informations on the response of heading to the different day length and temperature treatments and on the inheritance of heading dates, experiments were conducted at the field and greenhouse of the Crop Experiment Station, Suwon. Varieties used in this experiments were, early variety Yecora F70, medium varieties Suke #169, Parker and Yukseung #3, and late varieties Changkwang, Bezostaia, Sturdy and Blueboy. The parents and F$_1$s of partial diallel crosses of above eight varieties were subjected the following four different treatments; 1. high temperature and long day, 2. high temperature and short day, 3. low temperature and long day, and 4. low temperature and short day. The same materials were grown also in field condition. Parents, F$_1$ and F$_2$ generation were grown also in both greenhouse under high temperature and short day and in field. The results obtained were summarized as follow: 1. No effects of temperature and daylength on the number of leaves on the main stem were found when -varieties were vernalized. The number of main stem leaves were fewer for spring type of varieties than for winter type of varieties. 2. The effects of temperature and daylength on the days to flag leaf opening were dependent on the speed of leaf emergence. The speed of leaf emergence were faster for lower leaves than for upper leaves. 3. The response to short day and long day (earliness of narrow sense) of varieties were found to be direct factor responsible to physiology of heading dates in vernalized varieties. Great difference of varieties to heading date was found in high temperature and short day treatment, but less differences were found in high temperature and long day, low temperature and long day and low temperature and short day treatments respectively. The least varietal difference for heading dates was found in the field condition. 4. Changkwang and Parker were found to be the most sensitive to short day treatment (photosensitive) and the heading of these varieties were delayed by short day treatment. No great varietal differences were found among other varieties. 5. Varietal differences of heading dates due to daylength were greater in high temperature than in low temperature. 6. Varietal differences of heading dates due to temperature were not great. but in general the heading dates of varieties were faster under high temperature than under low temperature. 7. Earliness of heading dates was due to partial dominance effect of genes involved in any condition. The degree of dominance was greater under short day than under long day treatment. 8. The varietal differences of heading date under high temperature and long day were due to earliness or narrow sense (response to long day) of varieties. The degree of dominance was greater for Yecora F70, spring type than for other winter type of varieties. No differences or less differences of degree of dominance was found among winter type of varieties. The estimated number of effective factor concerned in the earliness of narrow sense was one pair of allele with minor genes. 9. The insensitivity of varieties to short day treatment in heading dates was due to single dominant gene effect. Under the low temperature the sensitivity of varieties to short day treatment was less apparent. 10. The earliness of short day and long day (earliness of narrow sense) sensitivities of varieties appearea to be due to partial dominance of earliness over lateness. In strict sense, the degree of the dominance should be distinguished. 11. Dominant gene effects were found for the thermo-sensitivity of varieties, and the effect was less, significant than the earliness in narrow sense. 12. One pair of allele, ee and EE, for photosensitivity was responsible for the difference in the heading dates between Changkwang and Suke #169. Two pairs of alleles, ee, enen and EE, EnEn. appeared to be responsible for the difference between Changkwang and Yecora F70. The effects of EE and EnEn were, additive to the earliness and the effects of EE were greater than EnEn under short day. However, the effects of EE were not evident in long day but the effects of EnEn were observed in long day. 13. Two pairs of dominant alleles for the earliness were estimated from the analysis of F$_1$ diallels in the field but the effects of these alleles in F$_2$ were not apparent due to low temperature and short day treatment in early part of growth and high temperature and long day treatment in later part of growth. The F$_2$ population shows continuous variation due to environmental effects and due to other minor gene effects. 14. The heritabilities for heading dates were ranged from 0.51 to 0.72, indicating that the selection in early generation might be effective. The extent of heritability for heading dates varied with environments; higher magnitude of heritability was obtained in short day treatment and high temperature compared with long day and low temperature treatments. The heritabilities of heading date due to response to short day were 0.86 in high temperature and 0.76 in low temperature. The heritabilities of heading date due to temperature were not significantly high. 15. The correlation coefficients of heading dates to the number of grains per spike, weight of 1, 000 grains. and grain yield were positive and high, indicating the difficulties of selections of high yielding lines from early population. But no significant correlation coefficient was obtained between the earliness and the number of spikes, indicating the effective selection for high tillering from early varieties for high yielding.

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Effects of Soil Organic Matter Contents, Paddy Types and Agricultural Climatic Zone on CH4 Emissions from Rice Paddy Field (벼 논에서 토양 유기물 함량, 논 유형 및 농업기후대가 CH4 배출에 미치는 영향)

  • Ko, Jee-Yeon;Lee, Jae-Saeng;Woo, Koan-Sik;Song, Seok-Bo;Kang, Jong-Rae;Seo, Myung-Chul;Kwak, Do-Yeon;Oh, Byeong-Gun;Nam, Min-Hee
    • Korean Journal of Soil Science and Fertilizer
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    • v.44 no.5
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    • pp.887-894
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    • 2011
  • To evaluate the effects of abiotic factors of paddy fields on greenhouse gases (GHGs) emissions from rice paddy fields, $CH_4$ emission amounts were investigated from rice paddy fields by different soil organic matter contents, paddy types, and agricultural climatic zone in Yeongnam area during 3 years. $CH_4$ emission amounts according to soil organic matter contents in paddy field were conducted at having different contents of 5 soil organic matters fields (23.6, 28.7, 31.0, 34.5, and $38.0g\;kg^{-1}$), The highest $CH_4$ emission amount was recorded in the highest soil organic matters plot of $38.0g\;kg^{-1}$. High correlation coefficient (r=$0.963^{**}$) was obtained between $CH_4$ emissions from paddy fields and their soil organic matter contents. According to paddy field types, $CH_4$ emission amounts were investigated at 4 different paddy fields as wet paddy, sandy paddy, immature paddy, and mature paddy. The highest $CH_4$ emissions was recorded in wet paddy (100%) and followed as immature paddy 64.0%, mature paddy 46.8%, and sandy paddy 23.8%, respectively. For the effects of temperature on $CH_4$ emissions from paddy fields, 4 agricultural climatic zones were investigated, which were Yeongnam inland zone (YIZ), eastern coast of central zone (ECZ), plain area of Yeongnam inland mountainous zone (PMZ), and mountainous area of Yeongnam inland mountainous zone (MMZ). The order of $CH_4$ emission amounts from paddy fields by agricultural climatic zone were YIZ (100%) > ECZ (94.6%) > PMZ (91.6%) > MMZ (78.9%). The regression equation between $CH_4$ emission amounts from paddy fields and average air temperature of Jul. to Sep. of agricultural climatic zone was y = 389.7x-4,287 (x means average temperature of Jul. to Sep. of agricultural climatic zone, $R^2=0.906^*$)

Mineral Nutrition of the Field-Grown Rice Plant -[I] Recovery of Fertilizer Nitrogen, Phosphorus and Potassium in Relation to Nutrient Uptake, Grain and Dry Matter Yield- (포장재배(圃場栽培) 수도(水稻)의 무기영양(無機營養) -[I] 삼요소이용률(三要素利用率)과 양분흡수량(養分吸收量), 수량(收量) 및 건물생산량(乾物生産量)과(乾物生産量)의 관계(關係)-)

  • Park, Hoon
    • Applied Biological Chemistry
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    • v.16 no.2
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    • pp.99-111
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    • 1973
  • Percentage recovery or fertilizer nitrogen, phosphorus and potassium by rice plant(Oriza sativa L.) were investigated at 8, 10, 12, 14 kg/10a of N, 6 kg of $P_2O_5$ and 8 kg of $K_2O$ application level in 1967 (51 places) and 1968 (32 places). Two types of nutrient contribution for the yield, that is, P type in which phosphorus firstly increases silicate uptake and secondly silicate increases nitrogen uptake, and K type in which potassium firstly increases P uptake and secondly P increases nitrogen uptake were postulated according to the following results from the correlation analyses (linear) between percentage recovery of fertilizer nutrient and grain or dry matter yields and nutrient uptake. 1. Percentage frequency of minus or zero recovery occurrence was 4% in nitrogen, 48% in phosphorus and 38% in potassium. The frequency distribution of percentage recovery appeared as a normal distribution curve with maximum at 30 to 40 recovery class in nitrogen, but appeared as a show distribution with maximum at below zero class in phosphorus and potassium. 2. Percentage recovery (including only above zero) was 33 in N (above 10kg/10a), 27 in P, 40 in K in 1967 and 40 in N, 20 in P, 46 in Kin 1968. Mean percentage recovery of two years including zero for zero or below zero was 33 in N, 13 in P and 27 in K. 3. Standard deviation of percentage recovery was greater than percentage recovery in P and K and annual variation of CV (coefficient of variation) was greatest in P. 4. The frequency of significant correlation between percentage recovery and grain or dry matter yield was highest in N and lowest in P. Percentage recovery of nitrogen at 10 kg level has significant correlation only with percentage recovery of P in 1967 and only with that of potassium in 1968. 5. The correlation between percentage recovery and dry matter yield of all treatments showed only significant in P in 1967, and only significant in K in 1968, Negative correlation coefficients between percentage recovery and grain or dry matter yield of no or minus fertilizer plots were shown only in K in 1967 and only in P in 1968 indicating that phosphorus fertilizer gave a distinct positive role in 1967 but somewhat' negative role in 1968 while potassium fertilizer worked positively in 1968 but somewhat negatively in 1967. 6. The correlation between percentage recovery of nutrient and grain yield showed similar tendency as with dry matter yield but lower coefficients. Thus the role of nutrients was more precisely expressed through dry matter yield. 7. Percentage recovery of N very frequently had significant correlation with nitrogen uptake of nitrogen applied plot, and significant negative correlation with nitrogen uptake of minus nitrogen plot, and less frequently had significant correlation with P, K and Si uptake of nitrogen applied plot. 8. Percentage recovery of P had significant correlation with Si uptake of all treatments and with N uptake of all treatments except minus phosphorus plot in 1967 indicating that phosphorus application firstly increases Si uptake and secondly silicate increases nitrogen uptake. Percentage recovery of P also frequently had significant correlation with P or K uptake of nitrogen applied plot. 9. Percentage recovery of K had significant correlation with P uptake of all treatments, N uptake of all treatments except minus phosphorus plot, and significant negative correlation with K uptake of minus K plot and with Si uptake of no fertilizer plot or the highest N applied plot in 1968, and negative correlation coefficient with P uptake of no fertilizer or minus nutrient plot in 1967. Percentage recovery of K had higher correlation coefficients with dry matter yield or grain yield than with K uptake. The above facts suggest that K application firstly increases P uptake and secondly phosphorus increases nitrogen uptake for dry matter yied. 10. Percentage recovery of N had significant higher correlation coefficient with grain yield or dry matter yield of minus K plot than with those of minus phosphorus plot, and had higher with those of fertilizer plot than with those of minus K plot. Similar tendency was observed between N uptake and percentage recovery of N among the above treatments. Percentage recovery of K had negative correlation coefficient with grain or-dry matter yield of no fertilizer plot or minus nutrient plot. These facts reveal that phosphorus increases nitrogen uptake and when phosphorus or nitrogen is insufficient potassium competatively inhibits nitrogen uptake. 11. Percentage recovery of N, Pand K had significant negative correlation with relative dry matter yield of minus phosphorus plot (yield of minus plot x 100/yield of complete plot; in 1967 and with relative grain yield of minus K plot in 1968. These results suggest that phosphorus affects tillering or vegetative phase more while potassium affects grain formation or Reproductive phase more, and that clearly show the annual difference of P and K fertilizer effect according to the weather. 12. The correlation between percentage recovery of fertilizer and the relative yield of minus nutrient plat or that of no fertilizer plot to that of minus nutrient plot indicated that nitrogen is the most effective factor for the production even in the minus P or K plot. 13. From the above facts it could be concluded that about 40 to 50 percen of paddy fields do rot require P or K fertilizer and even in the case of need the application amount should be greatly different according to field and weather of the year, especially in phosphorus.

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Determination of Total CO2 and Total Alkalinity of Seawater Based on Thermodynamic Carbonate Chemistry (해수중의 총이산화탄소와 총알칼리도 분석을 위한 탄산염 화학 이론 및 측정방법)

  • Mo, Ahra;Son, Juwon;Park, Yongchul
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.18 no.1
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    • pp.1-8
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    • 2015
  • To evaluate accuracy and precision of determination of total alkalinity ($Alk_T$) and carbon dioxide ($TCO_2$) derived from present study, experiment was applied with $CO_2$ CRM (Batch 132, Scripps Institution of Oceanography; $Alk_T=2229.24{\pm}0.39{\mu}mol/kg$, $TCO_2=2032.65{\pm}0.45{\mu}mol/kg$). As the result, average concentration of $Alk_T$ and $TCO_2$ was $2354.09{\mu}mol/kg$ (~5.6% difference with $CO_2$ CRM) and $2089.60{\mu}mol/kg$ (~2.3% difference with $CO_2$ CRM), respectively. For previous method (Gran Titration) by addition $NaHCO_3$ to deionized water($Alk_T$ $2023.33{\mu}mol/kg$), average concentration was $2193.39{\mu}mol/kg$ (sd=57.15, n=7). Whereas, average concentration was $2017.02{\mu}mol/kg$ (sd=10.98, n=7) for the present study. Recovery yield experiments of total alkalinity in deionized water and seawater were implemented by addition of $NaHCO_3$. The recovery yield of deionized water in the range 0 to $4952.39{\mu}mol/kg$ was 100.8% ($R^2$=0.999), and seawater in the range 0 to $2041.32{\mu}mol/kg$ was 102.3% ($R^2$=0.999). Comparison of $pCO_2$ sensor (PSI $CO_2-Pro^{TM}$) with present method showed very meaningful correlation coefficient ($R^2$=0.977) in the range of 427 to $705{\mu}atm$ and 9.16 to $15.24{\mu}mol/kg$ throught elapsed time for two weeks. Field experiment of diurnal variation of total carbon dioxide was accomplished at Sachon harbor in the coastal waters of East Sea of Korea. Concentration of $Alk_T$ and $TCO_2$ was increased during night, and decreased during daylight hours. The results showed mirror type between $TCO_2$ and dissolved oxygen, which was attributable to photosynthesis and respiration of phytoplankton. Also, open ocean field study was performed to obtain vertical profile of $Alk_T$ and $TCO_2$ in C-C zone (Clarion-Clipperton Fracture Zone), Northeastern Pacific. Average concentrations of $Alk_T$ in the surface mixed layer (0~60 m) and deeper layer below 200 m were $2422.38{\mu}mol/kg$ (sd=78.73, n=20) and $2465.87{\mu}mol/kg$ (sd=57.68, n=103), respectively. And average concentrations of $TCO_2$ were $2134.47{\mu}mol/kg$ (sd=65.4, n=20) and $2431.87{\mu}mol/kg$ (sd=65.02, n=103) in the same depth ranges such as $Alk_T$. Vertical distributions of $Alk_T$ and $TCO_2$ concentrations tended to increase with depth, and analyzed concentrations showed slightly higher than those of previous studies in this area.