• Korean Chemical Engineering Research
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• 제51권3호
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• pp.303-307
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• 2013

이 연구는 목질계 바이오매스에 대한 알칼리 용액의 침지와 침출 전처리의 효능을 비교한다. 볏짚과 보리짚과 같은 다양한 바이오매스는 수산화나트륨 용액, 수산화칼륨 용액, 암모니아수 그리고 탄산나트륨 용액에 의해 침지 공정으로 수행되었다. 암모니아수에 의해 전처리된 볏짚과 보리짚의 효소 소화율은 80% 이상으로 나타났다. 전처리된 유칼립투스 부산물, 낙엽송 그리고 리기다 소나무의 효소 소화율은 상대적으로 낮은 범위로 나왔다. 하지만 전처리된 유칼립투스 부산물은 초기 바이오매스에 비해 효소 소화율이 약 5배 증가되었다. 또한 침출 공정으로 전처리된 유칼립투스 부산물의 효소 소화율은 약 12배가 증가되는 것을 확인하였다.

• Journal of Microbiology and Biotechnology
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• 제30권11호
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• pp.1688-1696
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• 2020

Soil physical and chemical characteristics, soil potential denitrification rates (PDR), community composition and nirK-, nirS- and nosZ-encoding denitrifiers were studied by using MiSeq sequencing, quantitative polymerase chain reaction (qPCR), and terminal restriction fragment polymorphism (T-RFLP) technologies base on short-term (5-year) tillage field experiment. The experiment included four tillage treatments: conventional tillage with crop residue incorporation (CT), rotary tillage with crop residue incorporation (RT), no-tillage with crop residue retention (NT), and rotary tillage with crop residue removed as control (RTO). The results indicated that soil organic carbon, total nitrogen and NH₄⁺-N contents were increased with CT, RT and NT treatments. Compared with RTO treatment, the copies number of nirK, nirS and nosZ in paddy soil with CT, RT and NT treatments were significantly increased. The principal coordinate analysis indicated that tillage management and crop residue returning management were the most and the second important factors for the change of denitrifying bacteria community, respectively. Meanwhile, this study indicated that activity and community composition of denitrifiers with CT, RT and NT treatments were increased, compared with RTO treatment. This result showed that nirK, nirS and nosZ-type denitrifiers communities in crop residue applied soil had higher species diversity compared with crop residue removed soil, and denitrifying bacteria community composition were dominated by Gammaproteobacteria, Deltaproteobacteria, and Betaproteobacteria. Therefore, it is a beneficial practice to increase soil PDR level, abundance and community composition of nitrogen-functional soil microorganism by combined application of tillage with crop residue management.

• 한국토양비료학회지
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• 제44권1호
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• pp.1-7
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• 2011

Application of biochar to soils is proposed as a significant, long-term, sink for atmospheric carbon dioxide in terrestrial ecosystems. In addition to reducing emissions and increasing the sequestration of carbon, production of biochar and its application to soils will contribute improve soil quality and crop productivity. Objectives were i) to evaluate biochar productivity from crop residues using a low-cost field scale mobile pyrolyzer and ii) to evaluate characteristics of feedstocks and biochars from locally collected crop residues. Pyrolysis experiments were performed in a reactor operated at $400-500^{\circ}C$ for 3-4 hours using biomass samples of post-harvest residues of corn (Zea mays L.), cotton (Gossypium spp.), rice (Oryza sativa L.), sorghum (Sorghum bicolor L.) and wheat (Triticum aestivum L.). Feedstocks differed, but average conversion to biochar was 23%. Carbon content of biomass feedstock and biochar samples were 445 g $kg^{-1}$ and 597 g $kg^{-1}$, respectively. Total carbon content of biochar samples was 34% higher than its feedstock samples. Significant increases were found in P, K, Ca, Mg, and micro-nutrients contents between feedstock and biochar samples. Biochar from corn stems and rice hulls can sequester by 60% and 49% of the initial carbon input into biochar respectively when biochar is incorporated into the soils. Pyrolysis conversion of corn and rice residues sequestered significant amounts of carbon as biochar which has further environmental and production benefits when applied to soils. Field experiment with crop residue biochar will be investigated the stability of biochars to show long-term carbon sequestration and environmental influences to the cropping systems.

• 한국환경농학회지
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• 제40권3호
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• pp.161-168
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• 2021

BACKGROUND: Biochar has ability to reduce N loss, increase crop yield, and sequestrate carbon in the soil However, there is still limited study concerning the interactive effects of various biochars on NH₃ loss and plant growth. This study, therefore, was conducted to investigate the NH₄⁺ adsorption characteristics of biochar derived from rice and maize residues. METHODS AND RESULTS: By-products were pyrolyzed under oxygen-limited conditions at 300-700℃ for 1 hour and used for experiment of NH₄⁺ adsorption in aqueous solution. The adsorption characteristics of biochar were studied using Langmuir isotherm. Biochar yield and hydrogen content decreased with increasing pyrolysis temperatures, whereas pH, EC, and total carbon content increased. The biochar pyrolyzed at lower temperatures was more efficient at NH₄⁺ adsorption than those produced at higher temperatures. In addition, the R_L values, indicating equilibrium coefficient were between 0 and 1, confirming that the result was suitable for Langmuir isotherm. CONCLUSION: The maize stalk biochar pyrolyzed at 300℃ was the most efficient to adsorb NH₄⁺ from the aqueous solution. Furthermore, the adsorption results of this experiment were lower than those of other prior studies, which were ascribed to different experimental conditions such as ingredients, and pyrolysis conditions.

• 농약과학회지
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• 제21권1호
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• pp.68-74
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• 2017

고성능 액체크로마토그래프(HPLC)를 이용한 농업용수, 논토양, 현미 중 잔류 metamifop을 분석하기 위한 최적화한 추출법과 정제법을 조합하여 분석법을 개발하였다. 농업용수 중 잔류량은 ethyl acetate로 분배 추출, 논토양 중 잔류량은 아세톤으로 추출하고, $Extrelut^{(R)}$ NT 흡착 정제 후 실리카 SPE로 정제하여 HPLC로 분석하였다. 현미 중 잔류량은 아세톤으로 추출하고, $Extrelut^{(R)}$ NT 흡착 정제과정과 acetonitrile/hexane 분배 후 실리카 SPE로 정제하여 HPLC로 분석하였다. 확립된 분석법의 검출 한계(limit of detection, LOD)는 1.0 ng이었고, 시료의 양을 고려한 방법정량한계(method limit of quantitation, MLOQ)는 농업용수, 논토양과 현미 각각 0.001 mg/L, 0.01 mg/kg이었다. 표준검량선은 0.05 mg/kg 농도에서 5.0 mg/kg 범위까지 직선성을 보였고 ($R^2=0.9999$), 시료 중 회수율은 0.01, 0.05 mg/L 수준으로 첨가된 농업용수에서 각각 $91.3{\pm}3.5$, $93.2{\pm}6.3%$이었다. 0.1, 0.5 mg/kg 수준으로 첨가한 A토양시료 중 회수율은 각각 $92.5{\pm}4.0$, $92.7{\pm}4.0%$이었고, B토양시료 중 회수율은 $102.3{\pm}4.4$, $98.9{\pm}7.9%$로 확인되었다. 또한, 0.1, 0.5 mg/kg 수준으로 첨가한 현미시료 중 회수율은 각각 $93.0{\pm}6.9$, $85.0{\pm}3.5%$로 확립된 분석법은 농업용수, 논토양, 그리고 현미중 잔류 metamifop의 분석에 적용할 수 있을 것이다.

• 한국환경농학회지
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• 제14권3호
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• pp.312-318
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• 1995

본 실험은 수도체중의 benfuresate 잔류량과 배추중의 oxolinic acid 잔류량을 정량하여 이들 농약의 안전사용 기준설정및 최대 잔류 허용량 설정을 위한 기초자료를 얻기위하여 수행하였다. 논 토양에 benfuresate 입제를 0.6 kg a.i./ha의 수준으로 처리한 후 수도체를 재배, 수확한 후 현미와 볏짚 시료 중 benfuresate 잔류량을 정량하였으며, 배추 중 oxolinic acid의 잔류량 측정을 위해 각 처리구 당 15 kg a.i./ha의 수준으로 수확전 45, 30, 21, 15, 7, 3일에 배추에 직접 경엽 살포하였다. 본 실험에서 얻은 결과를 요약하면 다음과 같다. 1. 수도체와 배추 중의 benfuresate와 oxolinic acid의 회수율은 각각 $87{\sim}89%$, $90{\sim}951%$이었다. 2. 수도체 중 benfuresate의 잔류량은 $0.27{\sim}0.46mg/kg$이었다. 배추중의 oxolinic acid 의 잔류량은 $0.23{\sim}1.53mg/kg$의 범위였다. 3. 두 가지 공시약제의 잔류량은 처리횟수가 많을수록, 또 처리일수가 수확일에 가까울수록 증가하는 경향을 보여주었다. 4. 배추 중에 잔류하는 oxolinic acid는 first-order kinetics에 따랐으며, 잔류량은 시간이 경과함에 따라 감소하는 경향이었다. 5. 배추 중에 잔류하는 oxolinic acid의 잔류량은 6회 처리 또는 수확 3일전에 처리하였을 경우에도 FAO/WHO에서 설정한 최대 잔류 허용량인 5mg/kg에 미치지 않았다.

• 한국잡초학회지
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• 제30권4호
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• pp.361-370
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• 2010

HPLC/UVD를 이용한 현미와 볏짚 중 MCPA의 잔류분석방법 확립하고자 용매별 추출효율과 충진제별 정제효율을 검토한 결과, 용매별 추출효율은 시료 20g에 acetone 200mL와 1N-HCl 100mL의 혼합용매(pH 3.6)를 사용하는 것이 87%로 높은 효율을 보였고, 충진제별 정제효율은 florisil(6mL, 1g) Sep-$pak^{(R)}$ cartridge column에서 1% methanol/ acetonitile 용출이 83%의 효율을 나타내었다. 이 결과를 토대로 현미와 볏짚 시료 중의 MCPA 잔류분석을 수행하였는바, 평균회수율은 현미의 경우 96.0%와 94.9%이었으며, 볏짚의 경우 92.5%와 88.2%로 높은 회수율이었고, 실험의 정밀도는 상대표준편차 1.5~5.7%로 매우 높았다. 벼 이앙 후 30일에 bentazone+MCPA(11+1.2%) 합제를 ha당 30kg과 60kg을 각각 처리하여 재배한 현미와 볏짚 중 MCPA 잔류량은 모든 처리에서 식품의약품안전청이 권고한 잔류허용량인 $5{\mu}g\;mL^{-1}$ 미만이었다. MCPA의 HPLC 분석조건과 잔류분석절차의 결과는 가수분해, 유도체화, saponification과 같은 복잡한 분석절차를 생략할 수 있고, Rt가 기존 16.5 min.에서 6.5 min.으로 빨라져 인체위해성과 시간소모성의 단점을 개선하였으며, 회수율을 높이고 정밀도가 높은 결과로써 현미와 볏짚 중 HPLC에 의한 MCPA 잔류분석에 유용하게 적용할 수 있을 것으로 판단된다.

• 한국환경농학회지
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• 제20권4호
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• pp.269-276
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• 2001

Sulfamoylurea계 제초재의 일종인 cyclosulfamuron의 수도재배환경중 잔류특성을 평가하고자 2개 지역의 포장 및 실험실조건에서 토양 중 잔류성, 토양/토양수 및 수직적 잔류량 분포, 그리고 수확물인 현미 및 볏짚 중 잔류수준을 조사하였다. 경산 및 영천토양 중 잔류특성은 1차 분해반응의 양상을 보였으며 그 반감기는 포장과 실험실조건에서 각각 $17{\sim}30$일 및 $14{\sim}16$일로 나타났다. 입제살포 후 유효성분의 토양/토양수간 분포비율은 시간이 경과할수록 토양으로의 분포비율이 높아졌으며 토양 및 토양수에서의 반감기는 각각 19일과 10일이었다. 감수심 5 cm/일 조건으로 10일간 수행한 용탈 실험에서 cyclosulfamuron은 토심 $0{\sim}4\;cm$에 주로 분포하였으며 토양중 수직이동성은 상당히 제한적이었다. 포장조건에서 입제 및 액상수화제를 수확전 $120{\sim}150$일 전에 $1{\sim}2$회 처리하고 수확한 현미 중 잔류량은 제형, 살포시기 및 회수에 관계없이 모두 0.01 mg/kg 미만이었으며 볏짚중 잔류량은 $<0.02{\sim}0.05$ mg/kg 범위였다. Cyclosulfamuron의 토양 및 토양수 중 비교적 빠른 소실속도와 낮은 이동성을 고려할 때 약제살포에 따른 잔류분이 다른 환경계로의 전이되거나 후작물에 대한 2차 약해를 유발할 가능성은 매우 낮은 것으로 평가된다. 또한 수확물 중 낮은 잔류수준과 독성학적 특성을 감안할 때 수확물 중 잔류분으로 인한 만성독성학적 부작용은 무시하여도 좋다고 판단된다.

• Journal of Microbiology and Biotechnology
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• 제32권10호
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• pp.1292-1298
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• 2022

Soil autotrophic bacterial communities play a significant role in the soil carbon (C) cycle in paddy fields, but little is known about how rhizosphere soil microorganisms respond to different long-term (35 years) fertilization practices under double rice cropping ecosystems in southern China. Here, we investigated the variation characteristics of rhizosphere soil RubisCO gene cbbL in the double rice ecosystems of in southern China where such fertilization practices are used. For this experiment we set up the following fertilizer regime: without any fertilizer input as a control (CK), inorganic fertilizer (MF), straw returning (RF), and organic and inorganic fertilizer (OM). We found that abundances of cbbL, 16S rRNA genes and RubisCO activity in rhizosphere soil with OM, RF and MF treatments were significantly higher than that of CK treatment. The abundances of cbbL and 16S rRNA genes in rhizosphere soil with OM treatment were 5.46 and 3.64 times higher than that of CK treatment, respectively. Rhizosphere soil RubisCO activity with OM and RF treatments increased by 50.56 and 45.22%, compared to CK treatment. Shannon and Chao1 indices for rhizosphere soil cbbL libraries with RF and OM treatments increased by 44.28, 28.56, 29.60, and 23.13% compared to CK treatment. Rhizosphere soil cbbL sequences with MF, RF and OM treatments mainly belonged to Variovorax paradoxus, uncultured proteobacterium, Ralstonia pickettii, Thermononospora curvata, and Azoarcus sp.KH33C. Meanwhile, cbbL-carrying bacterial composition was obviously influenced by soil bulk density, rhizosphere soil dissolved organic C, soil organic C, and microbial biomass C contents. Fertilizer practices were the principal factor influencing rhizosphere soil cbbL-carrying bacterial communities. These results showed that rhizosphere soil autotrophic bacterial communities were significantly changed under conditions of different long-term fertilization practices Therefore, increasing rhizosphere soil autotrophic bacteria community with crop residue and organic manure practices was found to be beneficial for management of double rice ecosystems in southern China.

• Journal of Ginseng Research
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• 제20권1호
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• pp.96-100
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• 1996

In this experiment, germination test of ginseng seed and growth test of two year old ginseng in soil incorporated with quinclorac (3,7-Dichloro-8-quinoline carboxylic acid) were conducted to evaluate phytotoxicity caused by quinclorac residue in soil. Ginseng seed germiilation was hardly affected, but growth of ginseng seedling was retarded by quinclorac. The phytotoxicity of quinclorac on ginseng seedling was expressed at the lowest level tested, 3.75 g a.i./10a (118 of recommended rate for rice cultivation). The representative phytotoxicity in ginseng were decreased root weight, shortened leaf width and leaf length, and weak lateral root Quinclorac residue decreased by 1/4 in pot soil after 2 months and below 2 ppm in the paddy soil applied at usual rate (30 g a.i./10a) after 1∼ 2 years. Below 2 ppd ginseng did not show any phytotoxicity symptom.