• 미생물학회지
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• 제29권5호
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• pp.329-338
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• 1991

From July 1985 to December 1986, 28 variables of phycal-chemical factors, bacteria and heterotrophic activity were investigated 17 times at 3 stations in the estuary of Naktong River and the influences of environmental factors to bacterial population and heterotrophic activity were analyzed through multiple regression. The results of multiple regression were as follows. At station 1, total bacteria and heterotrophic bacteria(Z-25) could explain 57% of the variation of maximum uptake velocity for glucose and 54% of turnover time for glucose was explained by total coliform bacteria and MBOD, Sixty four percent of the variation of Kt+SN was accounted for salinity, MBOD-N and inorganic phosphate. Turnover rate for acetate was also accounted for the change of MBOD-P by 56%. At station 2 maximum uptake velocity for glucose depends on MBOD-N by 81%; turnover time on bacteria by 50%; Kt+Sn on avilable nutrient by 61%. More than 50% of maximum uptake velocity and turnover time for glucose were influenced by bacteria and that of Kt+Sn by the change of nutrient in the surface water of station 3. In the bottom water of station 3, the change of maximumuptake velocity, turnover time and Kt+Sn for glucose was controlled by total bacteria and available nutrient, bacteria, the change of nutrient salts respectively. On the whole, more than 50% of maximum uptake velocity and turnover time for glucose could be due to the change in the number of bacetria and the value of Kt+Sn was affected by the change of nutrient salts. Turnover rate for acetate was controlled by available phosphate at station 1 and by bacteria at station 2 and 3, which showed a distinct difference between the environmental factors which govern the rate of glucose and acetate uptake in the Naktong esturine ecosystem. And bacterial communities were controlled by available nutrients at station 1, by nutrient salts and salinity at station 2 and in the surface water of station 3 and by salinity in the bottom water of station 3.

• Asian-Australasian Journal of Animal Sciences
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• 제33권7호
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• pp.1087-1095
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• 2020

Objective: The present study aimed to evaluate the effects of γ-aminobutyric acid (GABA)-producing bacteria (GPB) on in vitro rumen fermentation and on the growth performance and meat quality of Hanwoo steers. Methods: The effects of GPB (Lactobacillus brevis YM 3-30)-produced and commercially available GABA were investigated using in vitro rumen fermentation. Using soybean meal as a substrate, either GPB-produced or commercially available GABA were added to the in vitro rumen fermentation bottles, as follows: control, no additive; T1, 2 g/L GPB; T2, 5 g/L GPB; T3, 2 g/L autoclaved GPB; T4, 5 g/L autoclaved GPB; T5, 2 g/L GABA; and T6, 5 g/L GABA. In addition, 27 Hanwoo steers (602.06±10.13 kg) were subjected to a 129-day feeding trial, during which they were fed daily with a commercially available total mixed ration that was supplemented with different amounts of GPB-produced GABA (control, no additive; T1, 2 g/L GPB; T2, 5 g/L GPB). The degree of marbling was assessed using the nine-point beef marbling standard while endotoxin was analyzed using a Chromo-Limulus amebocyte lysate test. Results: In regard to in vitro rumen fermentation, the addition of GPB-produced GABA failed to significantly affect pH or total gas production but did increase the ammonia nitrogen (NH₃-N) concentration (p<0.05) and reduce total biogenic amines (p<0.05). Animals fed the GPB-produced GABA diet exhibited significantly lower levels of blood endotoxins than control animals and yielded comparable average daily gain, feed conversion ratio, and beef marbling scores. Conclusion: The addition of GPB improved in vitro fermentation by reducing biogenic amine production and by increasing both antioxidant activity and NH₃-N production. Moreover, it also reduced the blood endotoxin levels of Hanwoo steers.

• 생물환경조절학회지
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• 제32권4호
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• pp.328-335
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• 2023

적절한 양분 관리와 식물 생육 증진을 위해 토양의 양분 수준을 반영하는 토양 센서가 요구된다. 토양의 양분을 모니터링할 수 있는 센서가 없으므로 전기전도도(EC) 센서를 토양의 양분 수준을 평가 하는데 사용할 수 있다. 센서 EC 값과 토양 온도, 수분 함량과 양분 함량과의 관계를 파악하면 EC 센서를 활용한 토양 양분 관리가 가능할 것이다. 그러나 센서 EC 값과 식물이 이용할 수 있는 양분의 관계는 구명되지 않았다. 따라서 본 연구의 목적은 고추와 브로콜리의 생육 기간동안 요소 비료 처리가 토양 센서 EC 값에 미치는 영향을 평가하고 토양에 존재하는 식물 유효태 양분 함량을 예측하는 것이다. 재배기간동안 주기적으로 토양을 채취하여 pH, EC를 측정하고 유효태 양분 함량을 분석하였다. 센서 EC 값은 수분 함량이 높아질수록 증가하였고 비료부족 처리구의 EC 값이 가장 낮게 나타났다. 센서 EC와 실제 토양 양분 함량과의 상관관계를 파악하기 위해 주성분 분석을 실시하였다. 센서 EC는 질산태질소와 유효태 칼슘과 강한 양의 상관관계를 보였다. 또한, 칼슘, 마그네슘, 칼륨, 인, 황, 질소와 같은 유효태 양분을 합한 값은 센서 EC 값과 관련이 있었다. 따라서 노지에서 EC 센서를 이용하여 양분 함량을 예측함으로써 적절한 양분 관리를 할 수 있을 것이다.

• 한국토양비료학회지
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• 제49권6호
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• pp.712-719
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• 2016

Understanding N mineralization dynamics in soil is essential for efficient nutrient management. An anaerobic incubation experiment was conducted to examine N mineralization potential and N mineralization rate of the organic amendments with different C:N ratio in paddy soil. Inorganic N in the soil sample was measured periodically under three temperature conditions ($20^{\circ}C$, $25^{\circ}C$, $30^{\circ}C$) for 90 days. N mineralization was accelerated as the temperature rises by approximately $10%^{\circ}C^{-1}$ in average. Negative correlation ($R^2=0.707$) was observed between soil inorganic N and C:N ratio, while total organic carbon extract ($R^2=0.947$) and microbial biomass C ($R^2=0.824$) in the soil were positively related to C:N ratio. Single exponential model was applied for quantitative evaluation of N mineralization process. Model parameter for N mineralization rate, k, increased in proportion to temperature. N mineralization potential, $N_p$, was very different depending on C:N ratio of organic input. $N_p$ value decreased as C:N ratio increased, ranged from $74.3mg\;kg^{-1}$ in a low C:N ratio (12.0 in hairy vetch) to $15.1mg\;kg^{-1}$ in a high C:N ratio (78.2 in rice straw). This result indicated that the amount of inorganic N available for crop uptake can be predicted by temperature and C:N ratio of organic amendment. Consequently, it is suggested that the amount of organic fertilizer application in paddy soil would be determined based on temperature observations and C:N ratio, which represent the decomposition characteristics of organic amendments.

• 농업과학연구
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• 제44권2호
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• pp.211-220
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• 2017

We conducted this study to determine the recommended application rate of fertilizer for Houttuynia cordata Thunb cultivation. The effects of various application levels of N, $P_2O_5$, and $K_2O$ fertilizers on the growth of this plant were investigated and the associated changes in soil properties were evaluated in the field. Soil pH at harvest time of Houttuynia cordata Thunb did not differ from that before fertilization, whereas EC tended to decrease during cultivation. The soil organic matter (SOM) and available phosphorus increased after treatment, and the amount of applied fertilizer ($P_2O_5$) and available phosphorus were proportional. The nitrogen absorption amount increased in N 100% treatment, but decreased in N 150% treatment. The phosphorus absorption amount rose with the fertilizer treatment concentration until $P_2O_5$ 150% treatment. The amount of absorbed potassium decreased in treatments with $K_2O$ 150% and $K_2O$ 200%. The plant length was the longest in N 100%, $P_2O_5$ 150%, and $K_2O$ 200%. The stem diameter was estimated to be 3.46 - 3.67 mm in N 100 - 200% treatment, 3.55 - 3.67 mm in $P_2O_5$ 100 - 150%, and 3.79 mm in $K_2O$ 200%. The number of tillers did not differ amongst fertilization treatments. The fresh weight was summed to be 3.67 ton/10 a in N 100% treatment, 3.79 Mg/10 a in $P_2O_5$ 150%, and 3.83 Mg/10 a in $K_2O$ 150%. Thus, the relationship between the fertilizer amount and yields of the plant showed that the most economical quantity of fertilizers should be 10.2 N kg/10 a, 5.5 $P_2O_5$ kg/10 a, and 8.2 $K_2O$ kg/10 a for Houttuynia Cordata Thunb.

• Journal of Ecology and Environment
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• 제31권3호
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• pp.167-176
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• 2008

Atmospheric N deposition has far-reaching impacts on forest ecosystems, including on-site impacts such as soil acidification, fertilization, and nutrient imbalances, and off-site environmental impacts such as nitrate leaching and nitrous oxide emission. Although chronic N deposition has been believed to lead to forest N saturation, recent evidence suggests that N retention capacity, particularly in the forest floor, can be surprisingly high even under high N deposition. This review aims to provide an overview of N retention processes in the forest floor and the implications of changing C-N interactions for C sequestration. The fate of available N in forest soils has been explained by the competitive balance between tree roots, soil heterotrophs, and nitrifiers. However, high rates of N retention have been observed in numerous N addition experiments without noticeable increases in tree growth and soil respiration. Alternative hypotheses have been proposed to explain the gap between the input and loss of N in N-enriched, C-limited systems, including abiotic immobilization and mycorrhizal assimilation, both of which do not require additional C sources to incorporate N in soil N pools. Different fates of N in the forest floor have different implications for C sequestration. N-induced tree growth can enhance C accumulation in tree biomass as observed across temperate regions. C loss from forests can amount to or outweigh C gain in N-saturated, declining forests, while another type of 'C-N decoupling' can have positive or neutral effects on soil C sequestration through hampered organic matter decomposition or abiotic N immobilization, respectively.

• 한국토양비료학회지
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• 제41권1호
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• pp.26-33
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• 2008

유기농업체계가 토양의 비옥도와 지속가능성에 미치는 영향을 파악하기 위하여 유기농 사과과수원 토양의 양분상태를 관행농과 비교하여 조사하였다. 동일한 토양에 조성된 인접한 유기농 및 관행농 사과과수원을 선정하여 2006년 5월부터 10월까지 월별로 5-20 cm 깊이의 토양을 채취하였으며, 유기물, 총 질소 및 무기질소, 유효인산, 교환성 양이온, 가용성 미량원소의 함량을 조사하였다. 평균 유기물 함량은 유기농과 관행농 과수원 토양에서 각각 63.3 및 $31.0g\;kg^{-1}$으로 유기농 과수원 토양에서 훨씬 높았다. 총 질소 함량은 평균값으로 유기농과 관행농 과수원 토양에서 각각 3.3 및 $1.7g\;kg^{-1}$이었다. 유기농 과수원 토양에서는 암모늄 및 질산태 질소 함량이 작기 중에 비교적 안정한 수준을 지속적으로 유지하였으나 관행농 과수원 토양에서는 화학비료 시용으로 인하여 조사 초기에 그 함량이 아주 높았으며 8월까지 급격히 감소하였다. 유기농 과수원의 경우 유효인산은 5월에는 관행농 과수원에 비하여 낮았으나, 작기가 진행되면서 지속적으로 증가하여 8월에는 그 함량이 $1000mg\;P_2O_5\;kg^{-1}$ 이상으로 나타났다. 유효인산은 관행농과 유기농 과수원 모두에서 적정수준인 $200-300mg\;P_2O_5\;kg^{-1}$보다 훨씬 높았다. 교환성 K, Ca, Mg 함량은 관행농에 비하여 유기농 과수원 토양에서 상대적으로 높았다. 가용성 Cu, Fe, Mn 함량은 관행농 과수원 토양에서 높았으며, 0.1 N HCl 가용성 Zn 함량은 반대로 유기농 과수원 토양에서 높았다. 이상의 결과에서 보면 관행농과 유기농 과수원 토양 모두에서 각종 양분함량이 적정수준보다 높은 것으로 나타났으며, 화학비료를 사용하는 관행농에 비하여 유기농 과수원 토양에서 각종 양분 함량이 오히려 높았다. 이러한 양분 과다 현상은 토양과 주변 환경에 부정적인 영향을 미칠 것이며, 유기농업의 근본 목적에도 벗어나는 결과이다.

• 한국환경농학회지
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• 제33권4호
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• pp.298-305
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• 2014

본 연구는 실내의 일정한 조건하에서 녹비작물인 헤어리베치와 청보리를 토양에 단일 투입 혹은 혼합 투입하여 토양 내 무기태 질소 및 가스 형태의 질소 배출 정도를 조사하여 전체 질소 동태를 살펴보았다. 녹비작물의 처리 후 토양 내 총질소, $NH_3$, $N_2O$, $NH_4{^+}$, $NO_3{^-}$의 함량은 모든 조사기간 내 헤어리베치를 단독으로 투입한 처리구에서 가장 높은 것으로 나타났다. 토양으로부터 유실되는 가스 형태의 질소 대부분은 $NH_3$에 의한 것으로 판단된다. 17주간 발생되어진 $NH_3$와 $N_2O$의 함량은 헤어리베치를 단독으로 처리한 B:H(0:100) 보다 청보리와 헤어리베치를 혼합하여 처리한 B:H(50:50) 처리구에서 낮게 나타났다. 헤어리베치를 단독으로 처리하거나 헤어리베치와 청보리를 혼합하여 처리한 토양에서는 청보리를 단독으로 처리한 토양에 비해 생육 초기에는 식물에게 유효한 형태의 무기태 질소인 $NH_4{^+}$의 함량을 훨씬 증대시킬 수 있는 것으로 조사되었으며 생육 후기에는 $NO_3{^-}$의 함량을 증대시킬 수 있는 것으로 조사되었다. 그러나 헤어리베치를 단독으로 처리하였을 경우 현장조건에서 강우 시토양으로부터 쉽게 용탈되어 지하수로 유입될 수 있는 $NO_3{^-}$의 함량을 증가시킬 수 있다. 결론적으로, 현장조건에서 토양 내 유효태 질소 함량의 증대화 투입된 질소의 유실량 저감을 위해서는 헤어리베치의 단파보다는 청보리와 헤어리베치의 혼파가 추천된다.

• 한국동물생명공학회지
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• 제34권3호
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• pp.157-165
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• 2019

This study was conducted to analyze the diversity census of fecal microbiome in horses using meta-analysis of equine 16S rRNA gene sequences that are available in the Ribosomal Database Project (RDP; Release 11, Update 5). The search terms used were "horse feces (or faeces)" and "equine feces (or faeces)". A total of 842 sequences of equine feces origin were retrieved from the RDP database, where 744 sequences were assigned to 10 phyla placed within Domain Bacteria. Firmicutes (n = 391) and Bacteroidetes (n = 203) were the first and the second dominant phyla, respectively, followed by Verrucomicrobia (n = 58), Proteobacteria (n = 30) and Fibrobacteres (n = 24). Clostridia (n = 319) was the first dominant class placed within Bacteroidetes while Bacteroidia (n = 174) was the second dominant class placed within Bacteroidetes. The remaining 98 sequences were assigned to phylum Euryarchaeota placed within Domain Archaea, where 74 sequences were assigned to class Methanomicrobia. The current results will improve understanding of the diversity of fecal microbiome in horses and may be used to further analyze equine fecal microbiome in future studies.

• Structural Engineering and Mechanics
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• 제69권4호
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• pp.361-369
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• 2019

The determination of Paris' law parameters based on crack growth experiments is an important procedure of fatigue life assessment. However, it is a challenging task because it involves various sources of uncertainty. This paper proposes a novel probabilistic method, termed the S-N Paris law (SNPL) method, to quantify the uncertainties underlying the Paris' law parameters, by finding the best estimates of their statistical parameters from the S-N curve data using a Bayesian approach. Through a series of steps, the SNPL method determines the statistical parameters (e.g., mean and standard deviation) of the Paris' law parameters that will maximize the likelihood of observing the given S-N data. Because the SNPL method is based on a Bayesian approach, the prior statistical parameters can be updated when additional S-N test data are available. Thus, information on the Paris' law parameters can be obtained with greater reliability. The proposed method is tested by applying it to S-N curves of 40H steel and 20G steel, and the corresponding analysis results are in good agreement with the experimental observations.