• The Korean Journal of Ecology
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• 제16권1호
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• pp.115-131
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• 1993

Six nutrient cycles involving terrestrial plants are identified and characterized. Plants affect biotic and abiotic cycles through their effects on soil properties. They determine their internal nutritional status and nutrient concentrations in their environment via internal and external cycles. Contributions of organic matter to mycorrhizal, trophic, and detrital mediated external cycles and alterations of nutrient concentrations by plants can promote positive feedbacks leading to increased availability and retention of soil nutrients in open systems. Recognizing alternative cycles through plants leads to a definition of nutrient use efficiency for ecosystems: the ratio of system production to nutrient content of organic matter. A simple graph model to predict changes of nutrient use efficiency during primary succession is then presented.

• 농업과학연구
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• 제49권4호
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• pp.919-926
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• 2022

Fertigation, which has been introduced in agricultural fields since 1990, has been widely practiced in upland fields as well as in plastic film houses as part of the crop production system. In accordance with demands in the agricultural sector, a huge number of scientific studies on fertigation have been conducted worldwide. Moreover, with a combination of advanced technologies such as big-data, machine learning, etc., fertigation is positioned as an indispensable tool to achieve sustainable crop production and to enhance nutrient and water use efficiency. In this review, we focused on providing valuable information in terms of crop production and nutrient/water use efficiency. A variety of fertigation studies have described that enhancement of crop production did not differ relative to conventional method or slightly increased. In contrast, fertigation significantly improved nutrient/water use efficiency, with a reduction in use ranging from 20 to 50%. Water-soluble organic resources such as livestock manure and agricultural byproducts also have been identified as useful resources like chemical fertilizers. Furthermore, the initial irrigation point was generally recommended in a range of -10 - -40 kPa, although the point differed according to the crop and crop growth stage. From this review, we suggest that fertigation, which is closely integrated with advanced technology, could be a leading technology to attain not only food security but also carbon neutrality via improvement of nutrient/water use efficiency.

• 한국환경농학회지
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• 제27권3호
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• pp.267-273
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• 2008

안전농산물에 대한 국민의 관심 증대와 농업환경자원의 유지 보전을 위한 지속적인 농업생산 방안으로 친환경농업 육성의 필요성이 증대되어 왔다. 이에 우리나라에서는 친환경 농업이 빠르게 성장하여 1999년 1300호였던 인증농가가 2007년에는 100배 증가하여 13만호에 이르고 있다. 그러나 친환경농업의 빠른 증가 추세에도 불구하고 친환경농업이 농업생태계에 미치는 영향에 대한 정량적인 연구는 미흡한 실정으로 친환경농업의 올바른 확산을 위해서는 농업생태계에 미치는 영향을 규명하고, 지속가능성을 정량화하는 연구가 필요하다. 이에 친환경농업의 지속가능성을 평가하고자 2006년부터 2007년까지 완주군 고산면 광역친환경농업단지 벼유기농업단지에서 쌀생산 시 에너지효율 및 양분수지를 조사하였다. 그 결과 벼유기농업단지가 관행논보다 에너지효율은 낮았으나 재생가능한 에너지 자원을 사용하는 유기농법이 화학비료나 농약을 사용하는 관행농법에 비하여 자원이용의 지속가능도는 높았다. 또한 벼유기농업단지는 과량의 축분퇴비 시용으로 토양 내 인산과 칼륨이 과다 축적되어 있으므로 축분 퇴비의 시용량을 줄이고 질소대비 인산과 칼륨의 함량이 비교적 낮은 자운영 등을 이용한 시비개선이 필요할 것으로 판단된다.

• 한국토양비료학회지
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• 제50권5호
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• pp.489-496
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• 2017

This study was conducted to test the applicability of hydroxy radical reactor system, which applied advanced oxidation processes, to sterilize pathogenic bacteria for nutrient solution recycling in closed hydroponics. Removal efficiency was tested on 25 L of nutrient solution maxed with 10 mL culture solution of bacteria, E. coli, and R. solanacearum in a pilot tank. The testing conditions included various levels of hydroxy radicals resulting from air flow rates of 40, 80, and $120L\;min^{-1}$, and 12 hours processing time. The removal of bacteria, E. coli, and R. solanacearum by hydroxy radical in nutrient solution was significantly increased with an increase in the flow rate of the air from $40L\;min^{-1}$ to $120L\;min^{-1}$. The optimum removal efficiency was achieved at an air flow rate of $120L\;min^{-1}$ for 2 hours treatment. There were no significant differences in removal efficiency among bacteria, E. coli, and R. solanacearum for tested level and time of hydroxy radical. These results verified the efficiency of hydroxy radical in removing the pathogenic bacteria and the applicability of hydroxy radical reactor system in the field.

• Membrane and Water Treatment
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• 제15권1호
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• pp.1-9
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• 2024

Biological nutrient removal is gaining increasing attention in wastewater treatment plants; however, it is adversely affected by low temperatures. This study examined temperature effects on nutrient removal and morphological stability of the granular and denitrifying phosphorus accumulating organisms (PAO and DPAO, respectively) using sequencing batch reactors (SBRs) at 5, 10, and 20 ℃. Lab-scale SBRs were continuously operated using anaerobic-anoxic and anaerobic-oxic cycles to develop the PAO and DPAO granules for 230 d. Sludge granulation in the two SBRs was observed after approximately 200 d. The average removal efficiency of soluble chemical oxygen demand (SCOD) and PO₄^3--P remained >90% throughout, even when the temperature dropped to 5 ℃. The average removal efficiency of NO₃^--N remained >80% consistently in DPAO SBR. However, nitrification drastically decreased at 10 ℃. Hence, the removal efficiency of NH₄⁺-N was decreased from 99.1% to 54.5% in PAO SBR. Owing to the increased oxygen penetration depth at low temperatures, the influence on nitrification rates was limited. The granule in DPAO and PAO SBR was observed to be unstable and disintegrated at 10 ℃. In conclusion, morphological characteristics showed that changed conversion rates at low temperatures in aerobic granular sludge altered both nutrient removal efficiencies and granule formation.

• Asian-Australasian Journal of Animal Sciences
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• 제16권8호
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• pp.1158-1164
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• 2003

In two feeding experiments male and mixed-sex broiler chicks were offered diets based on sorghum and a wheatsorghum blend with two tiers of nutrient specifications, without and with microbial phytase (600 and 800 FTU/kg), from 7-25 and 1-42 days post-hatch, respectively. The nutrient specifications for protein, amino acids, energy density and phosphorus (P) of standard diets were reduced to formulate the modified diets on a least-cost basis. Calculated differences in nutrient specifications between standard and modified diets ranged from 14.3 to 17.1 g/kg crude protein, 0.24 to 0.40 MJ/kg apparent metabolisable energy (AME) and 1.06 to 1.20 g/kg available P. In both experiments, reduced nutrient specifications had a negative impact on growth rates and feed efficiency and phytase supplementation had a positive influence on growth performance and protein efficiency ratios (PER). Phytase addition to the less expensive, modified diets either partially or entirely compensated for reduced growth performance and, consequently, feed costs per kg of live weight gain were reduced. In Experiment 1, phytase increased (p<0.001) nitrogen-corrected AME (AMEn) from 15.39 to 15.89 MJ/kg dry matter. For nitrogen (N) retention there was an interaction (p<0.05) between diet type and phytase as the effects of phytase on N retention were more pronounced in the modified diets, with an increase from 0.512 to 0.561. These results demonstrate the positive effects of phytase on protein and energy utilisation, in addition to its established liberation of phytate-bound P and illustrate the feasibility of assigning nutrient replacement values to the feed enzyme for consideration in least-cost ration formulations. Further work is, however, required to define the most appropriate reductions in nutrient specifications in association with phytase supplementation.

• 한국환경보건학회지
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• 제40권4호
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• pp.322-329
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• 2014

Objectives: The purpose of this study was to investigate the effect of BIO-CLOD on advanced wastewater treatment for enhanced removal efficiency and meeting the stringent discharge water requirements of wastewater treatment plants. Methods: Two experimental apparatuses consisting of anaerobic, anoxic and aeration tanks were operated. One included a BIO-CLOD cultivation tank. Organic and nutrient parameters and removal efficiency were analyzed by pH, BOD, CODcr, SS, T-N and T-P. Results: The average removal efficiencies of BOD, COD and SS from the apparatus with BIO-CLOD tank installation were 95.5%, 88.6% and 92.9%, respectively, and these were higher than the results from the apparatus without BIO-CLOD. The average TP removal efficiency with BIO-CLOD tank marked 56.0%, higher than the 47.3% from the apparatus without one. BIO-CLOD showed a higher performance for TN removal at 49.6%, compared to the result without BIO-CLOD of 34.3% Conclusion: By reaction with BIO-CLOD, ammonia removal was effective in the aeration tank, as was phosphorus release in the anaerobic tank. Phosphorus luxury uptake and nitrification in aeration tank proceeded smoothly. The application of BIO-CLOD can improve the decrease of odor and settleability of activated sludge in a wastewater treatment plant, as well as increase the removal efficiency of organic and nutrient materials in water.

• 한국양식학회지
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• 제20권1호
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• pp.56-59
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• 2007

Effect of dietary nutrient composition on growth and body composition of juvenile olive flounder Paralichthys olivaceus with different feeding strategy was determined. Twenty-five fish averaging 16 g were randomly distributed into 12, 180 L flow-through tank each. Four treatments in triplicates were prepared: fish were fed to satiation twice daily by the control diet for 8 weeks as the control group (Con) and fish were fed to satiation twice daily by the control and high nutrient diets for 6 weeks after 2-week fasting (2WS-6WFC, 2WS-6WFHN, respectively) and finally, fish were fed to satiation twice daily by the high nutrient diet for the consecutive 3 days after 4-day fasting for 8 weeks (4DS-3DFHN). No significant difference was found in either survival or weight gain of flounder among treatments. Feed efficiency ratio (FER) for fish in the 2WS-6WFHN treatment was significantly higher than that for fish in the Con and 2WS-6WFC treatments. Protein efficiency ratio (PER) of fish in the 2WS-6WFHN and 4DS-3DFHN treatments was significantly higher than that of fish in the 2WS-6WFC treatment. In conclusion, manipulation of dietary nutrient composition and/or feeding strategy can effectively improve growth of juvenile olive flounder without growth retardation at restricted feeding regime.

• 한국유기농업학회지
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• 제20권2호
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• pp.211-220
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• 2012

탄질비가 다른 유기자재를 시용하여 벼를 유기재배 할 때 자재별 무기화 정도와 벼의 질소 이용효율을 조사하기 위해서 2009년부터 2011년까지 시험을 수행하였다. 유기자재 처리는 질소함량 90kg/ha 수준으로 가축분퇴비, 유박, 유박2배, 헤어리베치, 헤어리베치+호밀 처리구를 두었고 화학비료구와 대조구를 두었다. 유기자재 중 유박은 가장 낮은 탄소:질소비(탄질비)를 나타내었고 가축분퇴비가 가장 높은 탄질비를 보였다. 토양 pH, 탄소, 질소, 칼슘, 그리고 마그네슘 농도는 처리간에 차이가 관찰되지 않았다. 2009년과 2010년의 질소 이용효율은 유박처리구가 화학비료구와 헤어리베치 그리고 퇴비구보다 높았다. 강수량이 많았던 2011년에는 축분퇴비구가 질소이용효율이 높은 것으로 관찰되었다.

• 한국습지학회지
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• 제16권3호
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• pp.363-370
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• 2014

농촌 지역 마을하수도 보급률은 도시 지역에 비해 38% 정도 수준밖에 되지 않는다. 농촌 지역은 상수원 인근에 위치하여 농촌지역에서 발생하는 하수는 상수원 오염의 원인으로 알려져 있다. 그래서 정부에서는 마을하수도 관리에 많은 노력을 기울이고 있다. 본 연구에서는 동절기 마을하수도 영양염류 제거 효율을 분석하였으며, 안동 임하댐 인근에 위치한 봉화, 영양 그리고 안동의 신설된 마을하수도를 연구 대상으로 선정하였다. 동절기 마을하수도 영양염류 제거 효율은 체류 시간과 미생물 농도에 영향을 받는 것으로 나타났다. 따라서 마을하수도 운전 시 영양염류 처리를 위해 운전 조건 조절 및 유지관리가 필요하다는 것을 의미한다.