• 한국작물학회지
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• 제50권1호
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• pp.16-21
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• 2005

This study was conducted to establish the elaborate nitrogen fertilization method to enhance N use efficiency in direct-seeded rice on flooded paddy. The nitrogen uptake by rice plants was insignificant until 25 days after seeding, and increased gradually thereafter. During this early growth stage, rice plants absorbed only the $4\%$ of basal applied N, while the $45\%$ of N fertilizer remained in the paddy soil. The absorption of basal N by rice plants was almost completed at 46 days after application. Nitrogen top-dressed at 5-leaf stage was well matched to crop nutrient demand, so it could be absorbed so actively in 8days after application. As a result, we could cut down the amount of N fertilizer to $36\%$ of the basal N level without significant difference in yield. Plant recoveries of fertilizer $^{15}N$ applied with different application timings were $7.8\%$ for basal, $9.4\%$ for 5-leaf stage, $17.1\%$ for tillering stage, and $23.4\%$ for panicle initiation stage, respectively. When urea was applied with nitrogen fertilization practice based on basal incorporation (BN), plant recovery of $^{15}N$ at harvest was $31.0\%$, which was originated from $13.7\%$ for grain, and $21.3\%$ of the fertilizer $^{15}N$ remained in the soil, and the rest could be uncounted. Plant recovery of fertilizer $^{15}N$ applied with nitrogen fertilization practice based on topdressing at 5-leaf stage (TN), where N rate was reduced by $18\%$ compared with BN, was $35.1\%$ (grain $15.6\%$), and $19.9\%$ of the fertilizer $^{15}N$ remained in the soil, and the rest could be uncounted. TN showed a higher $^{15}N$ recovery than BN because it was to apply N fertilizer at a time to well meet the demand of rice plant direct-seeded on flooded paddy. We concluded that TN would be the nitrogen fertilization method to enhance N use efficiency in direct-seeded rice on flooded paddy.

• 한국작물학회지
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• 제51권1호
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• pp.32-40
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• 2006

The nitrogen (N) absorption and partition of the rice plants are important indicators that can be used to improve the N use efficiency (NUE) of the plants. Improving the plant NUE can help to avoid nutrient waste that may cause environmental pollution. To investigate the N absorption and partition of the rice plants, Hwaseongbyeo (Japonica) and Dasanbyeo (indica/japonica) were applied with N fertilizers at the rates of 60, 120, and 180 kg N per ha in paddy field. Also micro plots of $0.81m^2$ were established inside each plot for application of $^{15}N-labeled$ fertilizer. The differences in N utilization of the rice plants were associated with the total N absorption and partitioning after the heading stage. In the grain filling period, the increase of nitrogen content in the total and leaf blades of Dasanbyeo was higher than that of Hwaseongbyeo. Soil N was the main contributor for the increase of total N of Dasanbyeo during the grain filling period. The N fertilizer uptake rate of Hwaseongbyeo rapidly increased with the increment of N fertilization rate. In Dasanbyeo, N fertilizer uptakes were similar under all rates and times of N application. From heading stage to harvest, Dasanbyeo continued accumulating nitrogen, whereas Hwaseongbyeo had small changes. In conclusion, the difference in nitrogen absorption and partition after heading of the two cultivars was caused by the ability of Dasanbyeo to accumulate and remobilize soil nitrogen to the grains during the grain filling period.

• 한국환경농학회지
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• 제36권3호
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• pp.147-153
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• 2017

본 연구는 기상 조건 및 관개 여부가 양분용탈 및 콩의 양분 흡수에 영향을 미치는지 평가하기 위하여 중량식 라이시미터에서 2015년부터 2016년까지 콩을 재배한 결과를 제시하였다. 콩 재배기간인 6월부터 10월까지의 증발산량은 무관개구의 경우 강우에 따라 변동되었으며, 2016년 7월 중순부터 8월 말까지 지온상승 및 강우 빈도의 감소로 증발산량이 감소하다가 9월 중순 강우에 의해 유효수분 함량을 회복하여 생육 후기에 증발산량이 증가하였다. 질산태질소의 지하 용탈량은 2016년 7월 초 5일간 강우가 지속되었을 때 가장 많았으며, 그동안 지하배수가 거의 없었던 무관개구에서 더 높게 나타났다. 개화기 및 착협기인 7월 중순부터 8월까지 한발로 인하여 무관개구의 토양 수분함량은 7월 초의 50% 수준으로 유지되었으며, 콩 수량은 적습관개구의 25% 수준이었다. 적습관개구와 무관개구의 양분 흡수량을 비교한 결과 질소 흡수량이 적습관개구에서 20~50% 더 높았으며, 인산, 칼리 흡수량 차이는 미미하였다. 토양 수분함량은 콩의 질소 흡수에 영향을 미치며, 적정 수량을 생산하기 위해서는 관개를 통한 적정 수분 공급이 필수적이었다.

• 한국유기농업학회지
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• 제25권2호
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• pp.373-386
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• 2017

본 시험은 전국의 광역친환경 농업단지 중에서 모범적으로 친환경 농업을 실천하고 있는 3곳(장흥, 순천, 옥천)의 벼 농가를 대상으로 시기별로 양분 분석을 하였다. 장흥지역 농가만이 경축자원 순환농업을 실천하고 있는 것으로 관찰되었다. 광역친환경 벼 농업단지의 3~9월 사이의 시기별 토양 pH는 5.5~6.7의 분포를 보였고, EC는 $0.4{\sim}1.0dS\;m^{-1}$으로 나타났다. 시기별 토양 전질소는 순천 농가에서 높았고 칼륨은 옥천 농가에서 낮은 수준을 보였다. 시기별 토양 암모늄태 질소는 봄철 비료 시용으로 6월 전후에 상승하였고, 장흥 농가에서 가장 높은 수준을 보이다가 이후 크게 감소하였다. 수량과 수확지수가 가장 높았던 옥천 농가에서 ha당 연간 조수입이 다른 농가보다 세배 가까이 높은 수준을 보였다. 비교적 많은 비료를 투입한 옥천 농가에서 시기별 양분수지가 높았고, 순천 농가의 ha당 칼륨 수지는 9월에 약 -60 kg까지 관찰되어 칼륨 결핍에 따른 생산성 저하에 일부 영향을 주었을 것으로 추정되었다. 시기별 전질소와 인산수지는 장흥 농가에서 가장 낮은 수준을 보였고 벼 낟알의 질소이용효율도 가장 높아서 광역친환경 농업단지의 추천할 만한 사례 농가로 평가되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제31권5호
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• pp.672-676
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• 2018

Objective: An experiment was conducted to study the effect of a blend of essential oils (BEO) on enteric methane emission and growth performance of buffaloes (Bubalus bubalis). Methods: Twenty one growing male buffaloes (average body weight of $279{\pm}9.3kg$) were divided in to three groups. The animals of all the three groups were fed on a ration consisting of wheat straw and concentrate mixture targeting 500 g daily live weight gain. The three dietary groups were; Group 1, control without additive; Group 2 and 3, supplemented with BEO at 0.15 and 0.30 mL/kg of dry matter intake (DMI), respectively. Results: During six months feeding trial, the intake and digestibility of dry matter and nutrients (organic matter, crude protein, ether extract, neutral detergent fibre, and acid detergent fibre) were similar in all the groups. The average body weight gain was tended to improve (p = 0.084) in Group 2 and Group 3 as compared to control animals. Feeding of BEO did not affect feed conversion efficiency of the animals. The calves of all the three groups were in positive nitrogen balance with no difference in nitrogen metabolism. During respiration chamber studies the methane production (L/kg DMI and L/kg digestible dry matter intake was significantly (p<0.001) lower in Group 2 and Group 3 as compared to control animals. Conclusion: The results indicated that the BEO tested in the present study have shown potential to reduce enteric methane production without compromising the nutrient utilization and animal performance and could be further explored for its use as feed additive to mitigate enteric methane production in livestock.

• Asian-Australasian Journal of Animal Sciences
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• 제16권4호
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• pp.609-624
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• 2003

The genesis of methods for defining the nutritional value of feeds and the nutrient requirements of animals, and their development in the late 19th and early 20th centuries in Europe and the USA are outlined. Current energy and protein feeding systems for ruminants are described. Particular reference is made to the Australian systems which are applicable to grazing animals as well as to those given prepared feeds, and enable the effective nutritional management of a imals at pasture by means of the decision support tool GrazFeed. The scheme for predicting intakes by cattle and sheep from pastures allows for the effects of selective grazing on the composition of the feed eaten, and for reduction in herbage intake when a supplementary feed is consumed. For herbage of any given concentration of metabolizable energy (ME) in the feed dry matter the changes with season of year in the net efficiency of use of the ME for growth and fattening and in the yield of microbial crude protein, g/MJ ME, which both vary with latitude, are defined. An equation to predict the energy requirements for maintenance (MEm) of both cattle and sheep includes predictions of the additional energy costs incurred by grazing compared with housed animals and the cost, if any, of cold stress. The equation allows for the change in MEm with feed intake. A flexible procedure predicts the composition of liveweight gain made by any given breed or sex of cattle and sheep at any stage of growth, and the variation with rate of gain. Protein requirements for maintenance, production including wool growth, and reproduction, are related to the quantities of microbial true protein and undegraded dietary protein truly digested in the small intestine.

• 한국토양비료학회지
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• 제47권5호
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• pp.332-339
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• 2014

This research was performed to test the hypothesis that the optimal fertilization rate for red pepper is changed by soil moisture condition. The experiment was conducted in rainfall-intercepted fields in Suwon, South Korea from 2002 to 2003. Soil was irrigated at 30, 50, or 80 kPa of soil moisture tension at 20 cm soil depth in 2002 and 30, 50, 100, or 150 kPa in 2003. For both years, fertilization was performed with four levels: none, 0.5, 1, and 1.5 times of the recommended N, P, and K fertilization rate. The irrigation amount was the greatest at 30 kPa irrigation while the water use efficiency increased with decrease of irrigation amount. The Irrigation amount was 508 mm at 30 kPa irrigation and ranged from 355 mm to 435 mm at 50 kPa irrigation. The maximum yield was found at 30 kPa irrigation and 1.5 times of the recommend fertilization rate in 2002 and 2003. The yield index of red pepper increased linearly with the fertilization rate at 30 kPa which implied that excess irrigation induced nutrient leaching and reduced nutrient availability. The maximum yield in 50 kPa and 80 kPa was found at the recommend fertilization rate while the yield decreased by fertilization at 100 kPa and 150 kPa irrigation. It implies that reduction of fertilization is the feasible practice to mitigate drought stress in fields without stable irrigation resources.

• 생물환경조절학회지
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• 제13권4호
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• pp.266-270
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• 2004

장미 식물공장식 양액재배는 고품질의 절화를 대량으로 계획 생산할 수 있는 시스템으로 장미 수출증가에 따라 기존의 재배 방식에서 식물공장 형태로의 전환이 필수적이다. 또한 식물공장에서의 경제적이고, 효율적인 생산을 위한 지하부 환경의 최적 관리 기술 개발이 절실한 실정이다. 따라서 장미 식물공장에 적합한 single-stemmed rose 수경재배시 배양액의 온도과 같은 지하부 환경요인이 장미의 생육과 품질에 미치는 영향을 알아보고자 실험하였다. 배양액의 온도에 따른 'Red Velvet'의 광합성률, 증산량, 생육 및 수량이 $15\~20^{\circ}C$에서 높게 나타나 적정 배양액 온도임을 알 수 있었다. 반면에 'Vital'은 $10\~15^{\circ}C$에서 생육이 가장 왕성하고 $30^{\circ}C$의 고온에서는 거의 생육이 이루어지지 않아 'Red Velvet'과는 달리 고온의 배양액에 대한 적응력이 낮은 것으로 나타났다.

• 해양환경안전학회지
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• 제14권2호
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• pp.105-109
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• 2008

우리나라에서 대부분의 호수는 인이 제한영양염인 것으로 나타나고 있다. 그러므로 인의 제거는 하수처리에서 중요한 공정이라고 할 수 있다. 그러나 많은 하수처리장은 재래식처리공정으로 처리하고 있으며 인의 제거율이 $10{\sim}30%$로 낮게 나타나 인의 제거공정은 필요하게 되었으며 패각은 수중의 인을 제거할 수 있는 것으로 알려지고 있어서 인의 활용이 주목된다. 회분식으로 패각을 이용하여 인의 제거율을 조사한 결과 패각의 크기가 작을수록, pH가 높을수록 제거율이 높게 나타났다. 또한 칼슘의 주입농도를 달리하여 처리한 결과 칼슘의 농도가 높을수록 처리효율이 증가하였으며 칼슘의 농도를 20mg/L로 조절하여 실험한 결과 2시간 내에 90% 이상의 제거율을 나타내었다. 재순환을을 변화시켜 실험한 결과 재순환율이 증가할수록 제거율은 증가하였으며 PH 11에서 재순환율을 300%로 조절한 결과 인의 제거율은 80%가 되었다. 중탄신이온의 영향을 평가하기 위하여 중탄산이온의 농도를 달리하여 실험한 결과 중탄산이온의 증가에 따라 인의 제거율은 감소하는 것으로 나타났으며 감소하는 비율은 지수함수로 나타났다.

• ALGAE
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• 제37권3호
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• pp.213-226
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• 2022

Aquaculture is one of the fastest growing food producing sectors; however, intensive farming techniques of finfish have raised environmental concerns, especially through the release of excessive nutrients into surrounding waters. Biodiversity has been widely shown to enhance ecosystem functions and services, but there has been limited testing or application of this key ecological relationship in aquaculture. This study tested the applicability of the biodiversity-function relationship to integrated multi-trophic aquaculture (IMTA), asking whether species richness can enhance the efficiency of macroalgal bioremediation of wastewater from finfish aquaculture. Five macroalgal species (Chondrus crispus, Fucus serratus, Palmaria palmata, Porphyra dioica, and Ulva sp.) were cultivated in mono- and polyculture in water originating from a lumpfish (Cyclopterus lumpus) hatchery. Total seaweed biomass production, specific growth rates (SGR), and the removal of ammonium (NH₄⁺), total oxidised nitrogen (TON), and phosphate (PO₄^3-) from the wastewater were measured. Species richness increased total seaweed biomass production by 11% above the average component monoculture, driven by an increase in up to 5% in SGR of fast-growing macroalgal species in polycultures. Macroalgal species richness further enhanced ammonium uptake by 25%, and TON uptake by nearly 10%. Phosphate uptake was not improved by increased species richness. The increased uptake of NH₄⁺ and TON with increased macroalgal species richness suggests the complementary use of different nitrogen forms (NH₄⁺ vs. TON) in macroalgal polycultures. The results demonstrate enhanced bioremediation efficiency by increased macroalgal species richness and show the potential of integrating biodiversity-function research to improve aquaculture sustainability.