• 한국토양비료학회지
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• 제50권2호
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• pp.100-105
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• 2017

Various methods for assessing soil total nitrogen (TN) and inorganic N content have been developed to manage nutrient and to understand N cycle in soil. This paper address the technical procedures in arable soil samples to conduct soil sampling, sample preparation, and measuring total N and inorganic N. Among various methods for measuring soil total nitrogen contents, Kjeldahl distillation and Indophenol blue method have widely used due to reliability and economic advances. Also, two methods can analyze more samples at the same time compared with other nitrogen measuring methods. For evaluating inorganic N content, mainly in forms of nitrate-N ($NO_3{^-}-N$) and ammonium-N ($NH_4{^+}-N$), extraction with a single reagent such as 2M KCl has been employed, followed by Kjeldahl distillation or indophenol blue methods.

• 농업과학연구
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• 제46권1호
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• pp.103-111
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• 2019

Gray mold caused by Botrytis cinerea on strawberry plants is an economically significant disease in Korea. The rates for diseased fruits are high during the strawberry harvesting period from December to February, especially in hydroponic cultivation. This study assessed the effect of the nitrogen type in the soil culture and the electrical conductivity (EC) of the nutrient solution in a hydroponic culture on the gray mold incidence in 'Seolhyang' strawberry plants. The nitrogen sources assayed included calcium nitrate tetrahydrate (CN4), calcium nitrate decahydrate (CN10), ammonium sulfate (AS), and commercial fertilizer 213 (213). The effect of the EC was tested at 0.5, 0.8, 1.0, and $1.5dS{\cdot}m^{-1}$. The occurrence of gray mold varied according to the nitrogen type. The disease incidence and nitrogen content for the main nitrogen type were higher compared to the non-treated control. The AS treatment showed the highest occurrence of tipburn and gray mold. The incidence of gray mold as well as the nitrogen and phosphorus content of the leaves increased as the EC level was increased. These results indicate that the incidence of gray mold in strawberry plants is related to the nitrogen content of the leaf and the EC of the nutrient solution.

• 한국토양비료학회지
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• 제25권2호
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• pp.168-174
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• 1992

밭토양(土壤)의 심층(深層)에 용탈집적(溶脫集積)되어 있는 nitrate를 작물(作物)이 이용(利用)할 때 이의 흡수(吸收)를 저해(沮害)하는 토양성분(土壤成分)을 찾고 그 요인(要因)을 구명(究明)하기 위하여 먼저 토양심도별(土壤深度別)로 nitrate와 chloride를 비롯한 몇가지 토양성분(土壤成分)들의 분포(分布)를 조사(調査)하였다. 1. 토심(土深) 150cm까지 몇가지 토양성분(土壤成分)들의 분포(分布)를 조사(調査)한 결과(結果) T-N함량(含量)은 표토(表土)에서 많았다가 하층(下層)으로 갈수록 적어졌고, nitrate의 함량(含量)은 아래로 갈수록 적어지다가 토심(土深)110cm부터는 다시 증가(增加)하여 nitrate의 용탈(溶脫) 집적현상(集積現象)을 보였다. 2. $^{15}N$의 천연함량비율(天然含量比率)인 T-N과 nitrate의 ${\delta}a^{15}N$ 값은 하층(下層)으로 갈수록 높아졌고 다른 보문(報文)의 토양(土壤)들에 비(比)하여 높은 편이었다. 그러나 조사포장내(調査圃場內)에서 이들의 변이(變異)는 크지 않았다. 3. chloride함량(含量)과 EC값은 nitrate가 집적(集積)된 하층(下層)으로 갈수록 급격(急激)히 높아져 chloride와 염기(鹽基)들이 용탈집적(溶脫集積)되었음을 알 수 있었고 이들 간(間)에는 고도(高度)의 정(正)의 상관(相關)이 있었다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.175-178
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• 2004

Little study has been published specifically addressing the dynamics of nitrate reducing bacteria (NBR) during the bioremediation of nitrate-contaminated aquifer. In our previous study we successfully quantified fumarate-enhanced microbial nitrate reduction rate in a nitrate-contaminated aquifer by using a series of single-well push-pull tests (PPTs). In this study we analyzed the suspended population during PPTs. To monitor changes in the microbial community, PCR amplification of 16S rDNA genes and denaturing gradient gel electrophoresis (DGGE) were used to study the dynamics of the bacterial community in detail. Before the stimulation of NBR, the dominant DGGE bands obtained by PCR were affiliated with V-Proteobacteria consisting of Acinetobacter spp. and Pseudomonas fluorescens. However, as NBR biostimulation proceeded, the dominant patterns of DGGE bands changed, and they were affiliated with Azoarcus denitrificans Td-3 and Flavobacterium xanthum. Azoarcus denitrificans Td-3 is known to completely reduce nitrate to nitrogen gas. The series of single-well push-pull tests in this study should prove useful for conducting rapid, low-cost feasibility assessments for in situ denitrification and provide important information about which microorganisms play a key role in bioremediation of a nitrate contaminated aquifer.

• 한국토양비료학회지
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• 제20권1호
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• pp.35-41
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• 1987

질산태질소(窒酸態窒素)를 선택흡수(選擇吸收)하는 담배식물에 대하여 흡수된 $NO_3-N$의 각조직별(各組織別) 이동양상(移動樣相)과 질산환원효소(窒酸還元酵素)의 활성도(活性度)(nitrate reductase activity. NRA)를 조사하고 생육과정(生育過程)에서 출엽(出葉)된 잎들의 질산환원능력(窒酸還元能力)을 비교조사(比較調査)한 결과(結果) 1. 도관조직(導管組織)인 엽맥(葉脈)까지는 함유(含有)된 질소(窒素)의 대부분(大部分)이 $NO_3-N$으로써 무기태질소(無機態窒素)로 엽맥(葉脈)을 통과(通過)하며 엽육(葉肉)에서는 $NO_3-N$이 환원(還元)되어 무기태질소(無機態窒素)가 거의 검출(檢出)되지 않았다. 2. NRA는 성숙(成熟)된 잎에서 가장 왕성하였으며 분열생장중(分裂生長中)인 잎이나 도관조직(導管組織)에서는 환원기능이 매우 낮은 수준에 머물렀다. 3. 하위(下位)의 성숙엽(成熟葉)은 두껍고 수분(水分)을 많이 함유(含有)하였으며 가장 왕성한 질산환원능력(窒酸還元能力)을 보였다. 4. 생장조직(生長組織)으로 유기질소물질(有機窒素物質)을 공급(供給)하기 위하여 유식물(幼植物)때는 소수(小數)의 좁은 잎에서 높은 수준(水準)의 NRA를 유지(維持)했으나 생육(生育)이 진전되어 많은 잎이 착엽(着葉)되면서 상위(上位)쪽의 성숙엽(成熟葉)은 NRA가 낮은 수준에 머물렀다.

• 한국해양학회지:바다
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• 제17권2호
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• pp.120-129
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• 2012

낙동강 하구에 위치한 갯벌 퇴적물에서 2005년 7월부터 2006년 9월까지 퇴적물-수층을 통한 산소와 용존 무기질소 플럭스, 그리고 탈질소화율을 계절별로 조사하였다. 현장 조건 수온에서 퇴적물 배양을 통해 측정된 산소 플럭스의 범위는 $-37.0{\sim}0.5mmol\;O_2\;m^{-2}\;d^{-1}$이었고, 수온이 증가할수록 퇴적물에 의한 산소소모가 많아져, 수층에서 퇴적물로의 산소 플럭스가 증가하였다. 탈질소화율은 $4{\sim}2732{\mu}mol\;N\;m^{-2}\;d^{-1}$의 범위로 같은 방법으로 측정한 국내 연안의 결과보다 높은 값을 나타냈고 산소 플럭스와 유사한 계절변화를 보였다. 질소동위원소를 이용하여 측정된 탈질 소화율은 수층에서 퇴적물로 유입되는 질산염 플럭스와 높은 상관관계를 보였다. Isotope pairing technique에서 계산되는, 총 탈질소화 중 "수층에서 유입된 질산염을 이용하는 탈질소화($D_w$)"도 수층에서 유입되는 질산염 플럭스와 양의 상관 관계를 보여 수층에서 유입되는 질산염이 탈질소화의 계절변동의 원인임을 시사하였다. 여름철에 질산염농도가 높은 담수의 유입 증가가 낙동강 하구 퇴적물로의 질산염 유입과 탈질소화를 촉진시킨 것으로 추정된다. 낙동강 하구 퇴적물에서 생지화학적 과정의 일반적인 패턴 및 경향을 파악하기 위하여, 이 연구에서 측정된 여러 생지화학적 플럭스를 방향과 크기에 따라 분류하여 보았다. 그 결과, 수온과 질산염 유입 변화에 따라서 여름철에는 수층에서 퇴적물로의 산소와 질산염 플럭스가 높게 나타나고 탈질소화도 높은 반면, 여름철을 제외한 나머지 시기에는 이들 플럭스가 낮아, 갯벌 퇴적물의 생지화학적 과정이 낙동강 담수 유입에 민감하게 반응함을 알 수 있었다.

• KSBB Journal
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• 제5권2호
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• pp.151-158
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• 1990

부질소 1-B5 배지에서 단독 배양한 담배 배양세표의 nitrate reductase 활성은 1-B5 배지에서 배양한 담배 배양세포에 비해 50% 이상 감소되었으나 $10^{-4}$ sper-mine 처리구에서는 그 활성이 가장 증가되었으며, N.muscorum파 혼합 배양시 그 활성이 현저히 증가한 반면 polyamine은 거의 영향을 미치지 않았다. Glutamate dehydrogenase 는 혼합 배양시 담배 배양세포플 단독 배양하였플 때보다 약 4배 감소 되었으며, glutamate synthas$\xi$의 활성은 $10^{-4}M$ spermlne 처리구에서 혼합 배양 하였을 때 그 활성이 가장 높았다.

• Journal of Applied Biological Chemistry
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• 제48권1호
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• pp.11-15
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• 2005

Salinity of soils in greenhouse has been increased by massive application of fertilizers. Nitrogen fertilizer was most popular, and thus nitrate became the majority of soil salinity. Accumulation of nitrate led to deleterious effects on the growth and development of crops and vegetables. Microbial strains able to utilize nitrate and thus remove excess nitrate from farm land soils were isolated from 15 different soils of greenhouses and plastic film houses. Four strains able to grow in medium containing 50 mM $KNO_3$ were isolated, among which only E0461 showed high capacity of nitrate uptake. Nitrate uptake by E0461 was dependent on culture medium and was increased by addition of tryptone and peptone. Although E0461 was able to grow without tryptone and peptone, growth was slow, and no nitrate uptake was observed. Nitrate appeared to facilitate E0461 growth in the presence of tryptone and peptone. Through kinetic analysis, nitrate uptake was measured at various concentrations of nitrate, and half-life was calculated. Nitrate concentration decreased with increasing incubation period, and plot between half-lives and initial concentrations of nitrate fitted to single exponential function. These results suggest one major factor plays an important role in microbial nitrate uptake.

• 한국농공학회논문집
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• 제59권4호
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• pp.1-15
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• 2017

Eutrophication of surface waters is of concern worldwide, because it can result in many undesirable water-quality and ecological problems, such as hypoxic 'dead' zones and harmful algal blooms, both associated with considerable economic costs. In this study, we used LSM (Land Surface Model) to simulate nitrogen in five major rivers in the Southern Korean Peninsula. The main objective of this research was to enhance nitrogen data for input of LM3V model in South Korea. Input data for nitrogen fluxes were categorized into three sections including agriculture fertilizer, livestock manure, atmosphere deposition, biological fixation, and sewage pollutants were used as the nitrogen input. For using LM3V model, the nitrogen input data were regenerated by considering states of agriculture and industry in South Korea at a $1/8^{\circ}$ resolution. Then, we simulated stream/river flows and N loads throughout the entire drainage networks in South Korea at a $1/8^{\circ}$ resolution. By using the same parameters for the entire country ($100,210km^2$), composed of 5 river basins with varying climate and land use, the model simulates spatial (11 sites) and temporal (1999~2010) patterns of flows and nitrate-N loads are resonable by comparing observed flow and nitrate-N loads. The r (Pearson's linear correlation) for water temperature, flow and nitrate-N at river were 080~0.93, 0.62~0.92 and 0.5~0.9 respectively. Based on enhanced N input data and model results, we find that LM3V model as land surface model can be applied in South Korea with interaction of atmosphere and land conditions.

• Asian-Australasian Journal of Animal Sciences
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• 제24권3호
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• pp.358-363
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• 2011

To investigate the effect of nitrogen fertilization on the quality of tropical grass silage, guinea grass grown with 3 types of nitrogen fertilizers, namely, urea, ammonium sulfate, and compound fertilizer 804, at 2 fertilization levels, 0.5 and 2.5 kg $Na^{-1}$ (0.5 N and 2.5 N, respectively), was subjected to silage fermentation. Silage fertilized with 0.5 N showed butyrate-dominant fermentation, irrespective of the type of fertilizer used. On the other hand, fermentation of silage fertilized with 2.5 N was significantly affected by the type of fertilizer used; fertilization with ammonium sulfate and compound fertilizer 804 resulted in silage that contained a large amount of butyrate and no lactate; this silage was considered to be of a significantly low quality as compared with silage fertilized with 0.5 N. Among silage fertilized with 2.5 N, the desirable butyrate-free fermentation was found only in urea-fertilized silage, which had the best quality. Grass material fertilized with a high level of urea accumulated a relatively high concentration of nitrate nitrogen (0.22% dry matter). Our results presented here suggest that nitrogen fertilizer management could affect the quality of tropical grass silage and that a relatively high concentration of nitrate in silage may promote butyrate-free fermentation even in tropical grass silage.