Effects of Biochar Addition on Nitrogen Leaching and Soil Structure following Fertilizer Application to Rice Paddy Soil

Yoo, Gayoung,Kim, Hyunjin,Chen, Jingjing,Kim, Yesol Wiley (John WileySons) 2014 Soil Science Society of America journal Vol.78 No.3

<P>Nitrogen leaching from agricultural soils is a major source of pollution for adjacent water systems. Biochar application to agricultural soils was reported to manageably reduce N leaching. For the sustainable use of biochar application, a mechanistic understanding of the changes in N leaching induced by biochar treatment is urgently needed. In this study, the effects of biochar [rice (Oryza sativa L.) chaff] application to rice paddy soil (sandy loam) on leaching and soil structure were investigated. Free-draining lysimeters (0.2 m in diameter by 0.1 m in height) filled with 500 g of air-dried soil were treated with biochar at 0, 2, and 10% application rates (BC0, BC2, and BC10, respectively) and N fertilizer (NH4Cl) at 0 and 100 kg ha(-1) application rates (Fert0 and Fert100, respectively). During the 9-wk incubation, the concentration of dissolved C in the leachates was higher in the soils treated with BC2 and BC10 compared with that treated with BC0 in the Fert0 soil while there were no significant differences among the biochar treatments in the Fert100 soil. This result indicated that the labile portion of the applied biochar C was utilized by microbes as the amended N was metabolized. Nitrate contents in leachates from the BC2 and BC10 treatments were significantly smaller than in those from the BC0 soil. Soil analysis showed that NH4+ content decreased and NO3- content increased under BC10 treatment compared with BC0 treatment in the Fert100 soil, indicating that net N mineralization in the soil was enhanced under biochar treatment. We suggested that the NO3- retention in the biochar-treated soil was related to increased soil aggregation. The C contents in the wet stable aggregates of size 53 to 1000 mm were significantly increased by biochar addition. This size fraction of aggregates is related to soil mesopores, which are involved in the soil's water holding. The water holding capacity (WHC) was higher in the BC2 and BC10 soils than in the BC0 soil, suggesting that application of rice chaff biochar to rice paddy soil could reduce N leaching through the redistribution of soil pores by forming more wet stable aggregates.</P>

Effects of biochar addition to soil on carbon sequestration and microbial biomass

( Gayoung Yoo ),( Hyun-jin Kim ),( Yesol Kim ) 한국폐기물자원순환학회 2011 ISWA Vol.2011 No.0

Biochar application to soil has drawn much attention as a strategy to sequester atmospheric carbon in soil ecosystems. The applicability of this strategy as a climate change mitigation option is limited by our shallow understanding of soil responses such as changes in soil structure and microbial biomass. To evaluate the possibility of biochar application to agricultural systems, we conducted a short-term laboratory incubation at field capacity in the soils from PASTURE (silt loam) and RICE PADDY (silty clay loam) sites with and without two types of biochar (biochar from poultry manure, CHAR_M and from barley stock, CHAR_B). The carbon (C) and nitrogen (N) contents contained in total and particulate organic matter (POM) in soils were increased by addition of CHAR_B and CHAR_M. Degree of increase was much greater in the soils amended with CHAR_M. This indicates that formation of water stable aggregates was enhanced by CHAR_M addition. This result also implies that biochar addition creates a favorable environment for microbial growth and metabolism by enhancing soil structural stability. Microbial biomass N was greatly increased by addition of CHAR_M in both soils. Soil phosphatase activity was increased in the CHAR_B soil and N-acetylglucosaminidase activity was higher in the CHAR_B soil than in CHAR_S soil.

Variable effects of biochar application to soils on nitrification-mediated N₂O emissions

Yoo, Gayoung,Lee, Yong Oon,Won, Tae Jin,Hyun, Jun Ge,Ding, Weixin Elsevier 2018 Science of the Total Environment Vol.626 No.-

<P><B>Abstract</B></P> <P>Although a meta-analysis on biochar's effects on N<SUB>2</SUB>O emission reported an overall reduction in N<SUB>2</SUB>O emission by adding biochar to the soils, there are still variations in the changes in N<SUB>2</SUB>O emission, especially from field results. The objectives of this study are 1) to compare the effects of biochar addition on N<SUB>2</SUB>O emission between three agricultural upland field experiments, where soil water status was dry favoring nitrification and 2) to identify main factors explaining biochar's variable effects on N<SUB>2</SUB>O emission. Three field experiments were conducted: Exp A in the cultivated grassland treated with rice husk biochar at 2 ton ha<SUP>−1</SUP> + urea (CHAR) and with urea only (CON); Exp B in the cabbage field with CHAR and CON treatments; and Exp C in the pepper field with CHAR, CON, and CHAR + DCD (dicyandiamide, nitrification inhibitor) treatments. In Exp A and C, cumulative N<SUB>2</SUB>O emissions significantly increased by 82.5% and 55.8% in the CHAR than CON treatments, respectively, while in Exp B, there was no difference in cumulative N<SUB>2</SUB>O emission between the CHAR and CON. Based on results from using nitrification inhibitor and soil % water filled pore space (WFPS), we assumed that the main N<SUB>2</SUB>O production mechanism was nitrification. Our results suggest that soil water status right after urea application is the primary determinant of different effects of biochar on N<SUB>2</SUB>O emission in addition to soil C status and biochar's adsorption. Principal component analysis using the 25 compiled data also supported our results. This study identified the specific field conditions under which biochar could have stimulating effects on N<SUB>2</SUB>O emission. Mitigation potential of biochar application should be reconsidered if biochar and urea were amended to dry soils with low C contents.</P> <P><B>Highlights</B></P> <P> <UL> <LI> N<SUB>2</SUB>O emissions were increased or not changed when both biochar and urea were applied to dry soils with low C content. </LI> <LI> Soil water status right after urea and biochar application was the primary determinant to predict the effect of biochar on N<SUB>2</SUB>O emissions, together with soil C status and biochar's adsorptive capacity. </LI> <LI> Our study is unique in that we obtained the results from multiple field experiments covering the whole cropping periods. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Aggregate Dynamics Influenced by Biochar Addition using 13C Natural Abundance

Gayoung Yoo,Hyunjin Kim,Jong-Yun Choi,Yongsik Ok 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

Biochar, Beyond Agricultural Utilization

Gayoung Yoo,Jee Hwan Bae,Inhye Seo,Minseop Jung,Junge Hyun 한국신재생에너지학회 2022 AFORE Vol.2022 No.9

Development of a Methodology Assessing Rice Production Vulnerabilities to Climate Change : 기후변화가 농업생태계에 미치는 영향분석 - 벼 생산 취약성 평가방법론 연구

Gayoung Yoo,Jung Eun Kim 한국환경정책평가연구원 2007 한국환경정책평가연구원 연구보고서 Vol.- No.RE-14

기후변화 취약성 평가는 적응정책을 수립하는 데에 있어 반드시 필요한 과정이다. 본 연구는 농업에 있어서 기후변화 적응정책의 기반이 되는 벼 생산성 취약성을 평가하는 방법론을 개발하기 위해 수행되었다. 작물생산성은 농업용수의 사용과 밀접하게 연계되어 있으므로 벼 생산 취약성 지표에 생산량의 변화와 농업용수의 상태가 함께 고려되었다. 연구대상지는 한국의 남서쪽에 위치하고, 지역의 쌀 생산량이 전국의 약 35%에 달하는 전라도이다. 분석의 공간적 단위는 시, 군, 구 이고, 미래의 벼 생산량은 CERES-rice 모형을 이용하여 기상연구소에서 다운스케일링 한 A2 시나리오를 기반으로 모사되었다. 기후변화 취약성은 민감도와 적응능력의 함수로 표현되는데, 민감도와 적응능력이 서로 독립변수라는 가정 하에 지표를 개발하였다. 민감도 지수는 기준선으로 사용된 1971~2000년 사이의 평균 벼 생산량에 대한 상대적인 변화률(%)로 정의되었다. 모형 구동 결과에 따르면, 2001, 2030s, 2050s, 2080s 년대의 벼생산량은 각각 0.74%, 5.7%, 8.7%, 16.5% 만큼 감소하는 것으로 나타났다. 이에 따라 벼 생산량 민감도는 21세기 말에 접어 들면서 약간 민감(-)한 정도 에서 매우 민감(-)한 정도로 변화하는 것으로 예측되었다. 기후변화에 대한 민감도(-)가 가장 큰 지역은 전라도의 남서쪽 해안 이었다. 적응능력은 가뭄스트레스에 따른 적응능력 (ACDS; Adaptive capacity for drought stress)과 홍수 피해에 따른 적응능력 (ACFD; Adaptive capacity for flood damage)의 두 가지를 고려하였다. ACDS 지표를 계산하기 위해서 1991~2003년 사이 각 시, 군, 구 단위로 가용한 관개 용수의 양과 그 지역 작물의 용수 수요량을 비교하였다. 각 시, 군, 구의 ACDS 지표는 관개 용수 공급량이 작물의 용수 수요량보다 큰 시점이 차지하는 백분율로 계산하였다. 제안된 ACDS 지표는 기존에 제안된 저수지의 용수 공급가능량을 표현하는 SWSCI (Storage water supply capacity index)와 비교되었는데, 이들 두 지표는 지수함수적 관계에 있었으며(R²=0.8392), ACDS 지표는 SWSCI에 비해 특히 소규모 저수지에서 물공급과 수요의 균형을 보는 데에 더 유용하다고 분석되었다. 한편, ACFD 지표는 폭풍우나 태풍에 의한 농경지 및 농산물의 피해액에 관한 1991~2003년의 통계자료를 이용하였는데, 피해액이 클수록 ACFD 지표가 작아지는 관계를 반영하였다. 서로 다른 단위를 갖는 ACDS와 ACFD 지표를 표준화하기 위하여 UNDP에서 이용하는 dimension index를 활용하였다. 취약성 지표의 분포를 보면 취약성이 높은 지역은 대상지의 서쪽 해안과 동쪽 산악지역임을 알 수 있었다. 남서쪽 해안의 취약성이 21세기 후반으로 갈수록 높아지는 이유는 벼 생산량의 감소에 기인하는 반면, 동쪽 내륙지역의 높은 취약성은 홍수에 따른 피해가 큼으로 인해 ACFD 지표가 낮게 나타났기 때문이었다. 연구에서 평가된 기후변화의 취약성을 감소시키기 위한 적응조치로 제안된 것은 벼 이앙기의 조정, 종 교체 및 이모작의 가능성이다. 이 중 특히 조기 이앙을 실시 할 경우 대상지의 2001, 2030s, 2050s, 2080s의 취약성이 크게 감소되는 것으로 나타났다. 각 적응조치 들의 적용가능성이 초동적으로 검토되었는데, 이앙기 조정을 위해서는 관개용수 시스템과의 연동을 고려해야 하고, 종교체보다는 새로운 품종의 개량이 적합하다고 제안되었으며, 이모작의 경우는 관개시스템 및 조생종의 확보 등 농업 기술적인 측면의 발전이 선행 Assessing vulnerability to climate change is the first step that should precede setting up appropriate adaptation strategies. This study was conducted to develop a methodology to assess climate change vulnerabilities in rice production in order to provide background for future adaptation policies. Changes in rice yield and agricultural water status were integrated to suggest a rice production vulnerability index because agricultural productivity is closely related to agricultural water use. The study area was the southwestern part of Korea, Jeolla­do, where the percentage of rice yield to total rice production amounts to ca. 35 %. The spatial unit for analysis was conducted at the county (Si, Gun, Gu) level. Future rice yield change was simulated with the CERES­rice model using the downscaled A2 scenario of the Meteorological Research Institute (METRI). Vulnerabilities to climate change are expressed as a function of sensitivity and adaptive capacity based on the assumption that sensitivity and adaptive capacity are independent variables. A sensitivity index to climate change is determined based on the rice yield change ratio which is the percentage of relative changes in rice yield compared to the baseline yield (1971~2000). Yields in 2001, 2030, 2050 and 2080 were projected to decrease by 0.74%, 5.7%, 8.7%, and 16.5%, respectively. Accordingly, the sensitivity index was expected to change from slightly sensitive (­) to highly sensitive (­) towards the end of the 21<SUP>st</SUP> century. Increases in negative sensitivity were the greatest in the most southwestern parts of Jeolla­do. An adaptive capacity index is comprised of two aspects; Adaptive Capacity for Drought Stress (ACDS) and Adaptive Capacity for Flood Damage (ACFD). To calculate the ACDS indicator, data for crop water demand and the amount of irrigated water available within the county were organized on a monthly basis from 1991~2003. The ACDS indicator for each county was calculated as the percentage of data points where the irrigated water supply was greater than the crop water demand. The ACDS indicator was compared with SWSCI (Standard Water Storage Capacity Index) and the relationship showed high degree of fit (R²=0.8392) using the exponential function. The ACFD indicator was based on the statistical data of damage cost for agricultural land and products due to heavy rain and typhoons (1991~2003) and had the inverse relationship with damage cost. We used the dimension index proposed by UNDP for standardization of the ACDS and ACFD indicators. Distribution of a vulnerability index showed that there were highly vulnerable areas in the western part and eastern mountainous regions of the study area. The high vulnerability along the eastern seashore region was mainly due to the projected large reduction in rice yield, whereas the high vulnerability areas in the eastern inlands originated from the high susceptibility to flood damage. Adaptation strategies suggested to reduce vulnerabilities are early rice transplanting, species substitution, and possibility of dual cropping. Especially, the results showed that early rice transplanting had greatly reduced rice production vulnerabilities in the study area. The applicability of the options to the study area was preliminarily tested. This study provides a guideline to assess vulnerability to climate change that can be applied to other sectors. The suggested index of vulnerability is expected to be a useful tool to help set up location­specific adaptation strategies. However, to improve the suggested rice production vulnerability index to more comprehensive agricultural vulnerability indicator to climate change, changes and impacts due to sea level rise, agricultural water quality, and soil nutrient capacity, etc. should also be considered and incorporated in the vulnerability index.

Transport and Decomposition of Leaf Litter as Affected by Aspect and Understory in a Temperate Hardwood Forest

Yoo, Gayoung,Park, Eun-Jin,Kim, Sun-Hee,Lee, Hye-Jin,Kang, Sinkyu,Lee, Dowon The Korean Society for Integrative Biology 2001 Korean journal of biological sciences Vol.5 No.4

Transport of colored papers and decomposition of leaf litter of Quercus mongolica, Acer pseudo-sieboldianum, and Kalopanax pictus were investigated on three patches differentiated by aspect and understory in a temperate hardwood forest. Two patches are represented by dwarf bamboo (Patch SS) and herbaceous plants (Patch S), respectively, Iying on a south-west-facing slope. The other patch (Patch N) is located on a northeastfacing slope with herbaceous plants. Colored papers were placed on the patches to understand the pattern of litter movement on the ground. Papers were move dispersed in Patch S than in the other two patches. Some of the colored papers placed in Patch S moved upward. The results suggest that the litter movement is affected by aspect and that the leaf litter is retained by dwarf bamboo in Patch SS. Decay constant of Q. mongolica was significantly (p<0.05) lower than those of K. pictus and A. pseudo-sieboldianum. Decay rates of Q. mongolica were significantly different between Patches N and S and between Patches SS and S (p<0.05). On the other hand, decay rates of the other species were not significantly different among the three patches. The results suggest that aspect and understory exert an influence on redistribution and decomposition of leaf litter and that the effects could be different among the plant species.

우리나라 기후변화 영향평가 및 적응에 관한 제언

유가영(Yoo Gayoung) 경기연구원 2007 경기논단 Vol.9 No.4

Vulnerability assessment is the basis for setting up sound climate change policies. It should focus on a balance between top-down and bottom-up approaches. Top-down approach is based on biophysical impact assessment of climate change and scientific background, whereas bottom up approach is based on socio-economic aspects of climate change and local vulnerability indicators. In this paper, by reviewing basic concepts of climate change impact, vulnerability, and adaptation, together with case studies of national research and development and national adaptation policy framework, I suggested some points when establishing Korean adaptation policy framework.. In Europe such as Finland, France, and U.K., national climate change adaptation policies have already been set up and started to prepare the upcoming risks of climate change by minimizing negative impacts and exploiting potential opportunities. Through implementing three stages of national countermeasures for climate change convention, Korea has greatly augmented the awareness level of climate change and adaptation. However, Korea is still in the initial stage in terms of climate change science and policies. With these backgrounds, here are several suggestions for climate change impact assessment and adaptation. Firstly, I emphasized the importance of research and development (R & D) in developing methods on climate change impact and vulnerability assessment. Secondly, based on the improved adaptive capacity through R & D, setting up the governmental framework on climate change adaptation polices is needed. It includes listing of adaptation measures in many sectors (adaptation inventory) and the principles of prioritizing them. The two strategies in setting up adaptation polices are suggested which are efficiency and integrity. For efficiency, I suggest the adoption of the process of mainstreaming which is defined as “bring adjustments in ecological, social or economic systems into the common current of thought in society in response to expected climate impacts”. For integrity, the policies which aim at mitigation and adaptation at the same time should be implemented with high priority. Lastly, the development of appropriate strategies for international negotiation on adaptation was considered. The harmony between top-own and bottomup approach as well as between central and local governments will lead our country to set up a balanced adaptation policies through which climate change could turn out be a new opportunity in future sustainable development.

토양 탄소 저장 증진 솔루션: 토양 미생물과 탄소 분획

유가영(Gayoung Yoo),박예림(Ye Lim Park),현준기(Junge Hyun) 한국토양비료학회 2021 한국토양비료학회 학술발표회 초록집 Vol.2021 No.11

기후변화 완화 전략 중 하나로 토양 탄소 저장의 중요성이 강조되고 있다. 일반적으로 토양 탄소 저장은 단위면적 당 저장된 총 탄소량으로 표현하는데, 이는 토양 탄소가 다양한 형태로 저장되어 있어 물리화학적으로 높은 이질성을 갖다는 사실을 반영하지 못한다. 토양을 물리, 화학적인 방법으로 분리하여 토양 내에서 기능적 의의를 갖는 fraction으로 나누는 토양 분획은 토양 내 탄소가 저장되는 과정의 이해를 돕고 생태계 맞춤형 탄소 저장 증진 관리 방향을 설정하는데 유용하다. 본 연구에서는 초지, 농경지 및 도시 토양에서 총 탄소 및 분획별 탄소량을 정량하고 미생물 효소 활성도 차이와의 관계를 분석하였다. 또한 탄소 저장이 현저히 저하된 도시 토양에서 탄소 저장을 증진시키는 관리 방안을 제안하였다. 연구 대상지는 20년 이상 유지된 초지, 농경지와 도시공원 및 가로수이다. 각 대상지에서 0-15cm 깊이의 코어 샘플을 채취하여 밀도와 크기에 기반한 토양 분획을 실시하였다. 분리된 fraction은 Light fraction(LF), occluded particulate organic matter(POM), 그리고 mineral-associated organic matter(MAOM)이다. 또한, 총 및 분획별 탄소량과 세포외 효소 활성도를 분석하였다. 측정된 효소는 hydrolase인 β-glucosidase, β-cellobiosidase, β-xylosidase와 phenol oxidase이다. 그 결과 총 토양 탄소 저장량은 초지>농경지>도시공원>가로수 순이었으며, 안정한 형태로 저장된 탄소인 MAOM의 비율은 초지=농경지>도시공원>가로수 순이었다. 토양의 hydrolase activity는 토양 탄소 저장량이 클수록 높았으며, oxidase activity는 오히려 반대의 경향을 보였다. 도시 토양의 높은 oxidase activity는 높은 pH 및 자연생태계와는 다른 탄소의 질과 관련이 높았다. 도시토양의 C/H 비는 초지에 비해 유의하게 낮은데, 이는 도시 토양에 포함된 여러 유기 오염물질이 그 이유가 될 수 있다. 본 연구에서 탄소저장량이 가장 낮았던 가로수 토양의 탄소 저장증진을 위해 띠녹지 조성이라는 관리 효과를 확인한 결과, 가로수만 있는 토양에 비해 띠녹지 조성을 통한 다층식재가 총 탄소 저장량을 198% 증가시켰음을 볼 수 있었다. 그러나 토양 분획을 살펴본 결과, 증가의 원인은 거의 LF에 집중되어 있음을 알 수 있었다. 즉, 띠녹지 조성에 의해 증가된 토양 탄소 저장은 쉽게 분해되는 형태에 국한되어 있으며 안정한 형태의 탄소 저장으로 전환되지 못했음을 의미한다. 가로수 토양에 저장된 탄소가 안정화되기 위해서는 LF 비율에 비해 POM이나 MAOM의 비율이 높아져야 하는데 이를 위한 추가적인 관리로는 압밀완화 등의 토양 구조개선, 가로수 식재 시 마사토 투입과 함께 점토질을 함유한 토양 개량제 추가, 바이오차 투입 등이 있을 수 있다. 본 연구 결과, 토양탄소 저장증진의 효과를 확인하기 위해서는 총 탄소의 변화 모니터링만으로는 부족하며 토양 미생물 분석과 분획을 통해 저장된 탄소의 질과 안정한 형태의 탄소저장이 증진되었는지를 확인할 필요가 있음을 시사한다.

Engineering of Baeyer-Villiger Monooxygenase-based Escherichia coli Biocatalysts for the Biotransformation of Fatty Acids

Gayoung KIM,Juho YOO,Jaerin LEE,Jinbyung PARK 한국생물공학회 2023 한국생물공학회 학술대회 Vol.2023 No.4