메탄(CH4)은 지구 온난화에 크게 기여하는 온실가스이며, 우리나라 농업 분야에서 벼 재배는 메탄 배출의 주요한 원인으로 알려져 있다. 본 연구는 벼 뿌리의 형태학적 특성과 토양 환경이 메탄 배출 특성에 미치는 영향을 구명하기 위하여 온도 조절이 가능한 인공 유리 온실에서 삼광과 신동진 벼 품종을 대상으로 포트 실험을 수행하였다. 생육 단계별로 챔버를 이용한 메탄 가스 포집과 벼의 생육 특성 및 뿌리의 형태학적 특성을 조사하고 토양의 산화환원전위, 온도, 용존유기탄소를 함께 측정하였다. 두 품종 모두 유수형성기 이후 메탄 배출량이 급격히 증가하여 출수기에 최대 1.7-2.1 mg CH4 m-2 hr-1을 보였으며, 누적 메탄 배출량은 삼광 품종이 다소 높았으나 통계적으로 유의한 차이는 없었다. 벼 뿌리의 형태학적 특성은 두 품종 간 유의한 차이가 없었으나, 주요 생육 시기의 메탄 배출 변화와는 유사하였다. 또한, 토양 산화환원전위는 담수기간이 지속될수록 환원 조건이 더욱 형성되었다. 이는 토양 내 메탄생성균의 기질 공급 등의 유리한 조건을 형성하여 메탄 생성이 활발해졌을 것으로 판단된다. 이러한 결과는 벼 품종 및 재배 관리에 따른 농업 부문의 메탄 저감 전략 마련에 기초 자료로 활용될 수 있을 것으로 판단된다.

The commercial feed additive, native rumen microbes (RC), derived from a diverse microbial community isolated from the rumen of Hanwoo steers is being explored to enhance rumen fermentation and improve ruminant feed utilization. This study evaluated the impact of native rumen microbes supplementation on methane emissions, microbial diversity, and fermentation efficiency on in vitro assessment. Treatments were as follows: CON (basal diet, without RC); T1 (basal diet + 0.1% RC); T2 (basal diet + 0.2% RC). Rumen fermentation parameters, total gas, and methane production were assessed at 12, 24, and 48 h of incubations. The in vitro gas production was carried out using the Ankom RF Gas Production System. Supplementation of RC significantly reduced the total gas production at 12, 24, and 48 hours of incubation (p < 0.05). Volatile fatty acid concentrations were increased, while acetate and propionate were decreased (p < 0.05) at 48 h by the supplementation of RC. Notably, the 0.1% inclusion level of RC significantly reduced methane production by 28.30% and 21.21% at 12 and 24 hours. Furthermore, microbial diversity analysis revealed significant shifts (p < 0.05) in bacterial composition between the control and treatment groups, while supplementation also promoted the growth of bacterial populations, such as Succiniclasticum. These findings suggest that native rumen microbes supplementation, particularly at 0.1% inclusion level, can enhance rumen microbial composition while significantly reducing methane production in vitro.

This review examines the importance of measuring practical enteric methane emissions from ruminants, considering their significant impact on global warming. Global warming is significantly driven by an increase in greenhouse gases, with rising methane (CH4) emissions from ruminants accelerating global warming recently. To successfully mitigate CH4 emissions and establish effective strategies, it is essential to apply reliable measurement techniques. This will allow for an accurate assessment of on-farm CH4 emissions. The priority should be to gather CH4 emission data that reflects the actual state of CH4 emissions from ruminants. The review provides an overview of the methods used to measure CH4 emissions from ruminants by compiling existing researches. It introduces the concepts, principles, and limitations of these methods to facilitate comparisons between existing approaches. This review discusses methods for measuring enteric CH4 emissions from ruminants at the farm level, including the tracer technique, laser methane detector, GreenFeed, and sniffer system. These methods are highlighted as potential tools to accumulate substantial data on on-farm CH4 emission from domestic animals with provides examples of international cases. Among these, this review introduces the Sniffer method, a CH4 emission measurement techniques that are suitable for on-farm use under domestic conditions, and emphasizes the necessity of its application. In addition, by presenting international cases where predictive models were developed based on on-farm CH4 measurement techniques, it is projected that if predictive models for CH4 emissions are developed by accumulating data at the farm level, it can contribute to sustainable livestock industry in various promising ways.

메탄가스는 주요 온실가스 중 하나로 반추동물의 장내발효를 통해 발생하며, 이러한 경로의 메탄가스는 대한민국 축산부문 총 온실가스 발생량의 40% 이상을 차지한다. 이런 이유로 많은 연구자들은 반추동물에서 발생하는 메탄생성량을 줄이기 위한 시도를 계속해 왔다. 본 연구는 반추동물의 메탄발생량을 측정하기 위해 호흡대사챔버를 개발하고 호흡대사챔버의 정확성을 검증하기 위해 실시하였다. 호흡대사챔버는 25.4 m3 크기로 스테인리 스 플레이트로 내부를 완전히 밀폐하였다. 직경 Φ100의 공기 유입관과 배출관을 설치하였고, 공기 배출관에 에어모터를 설치하여 내부공기를 제거함과 동시에 유입관을 통해 배출된 만큼의 공기가 외부에서 유입되도록 하였다. 챔버 내 메탄가스 회수기능을 검증하기 위해 메탄표준가스 5L를 각 챔버에 주입하여 균일하게 확산시킨 후, 챔버 내부의 공기를 900 L/min의 속도로 제거하였다. 제거된 공기의 메탄가스 농도를 연속적으로 측정하여 주입된 메탄가스와 비교함으로써 회수율을 평가하였다. 챔버 내 표준가스는 평균 100분에 완전히 제거되었으며, 메탄가스의 회수율은 평균 109 ± 6.7%로 측정되었다. 호흡대사챔버의 실제 이용성을 평가하기 위해, 평균체중 581.9 ± 33.8 kg 의 한우 거세우 4두에게 비육후기 배합사료 9 kg과 볏짚 1 kg을 급여하며 메탄발생량을 측정하였다. 한우의 장내발효에 의한 메탄발생량은 평균 236.4 ± 105.44 L/day로 측정되었다. 본 연구에서 개발·검증한 호흡대사챔버는 국내 한우의 장내발효 메탄가스발생량 측정 시험에 적용 가능할 것이다.

In order to reduce odor and methane emission from the landfill, open biocovers and a closed biofilter were applied to the landfill site. Three biocovers and the biofilter are suitable for relatively small-sized landfills with facilities that cannot resource methane into recovery due to small volumes of methane emission. Biocover-1 consists only of the soil of the landfill site while biocover-2 is mixed with the earthworm casts and artificial soil (perlite). The biofilter formed a bio-layer by adding mixed food waste compost as packing material of biocover-2. The removal efficiency decreased over time on biocover-1. However, biocover-2 and the biofilter showed stable odor removal efficiency. The rates of methane removal efficiency were in order of biofilter (94.9%)>, biocover-1(42.3%)>, and biocover-2 (37.0%). The methane removal efficiency over time in biocover-1 was gradually decreased. However, drastic efficiency decline was observed in biocover-2 due to the hardening process. As a result of overturning the surface soil where the hardening process was observed, methane removal efficiency increased again. The biofilter showed stable methane removal efficiency without degradation. The estimate methane oxidation rate in biocover- 1 was an average of 10.4%. Biocover-2 showed an efficiency of 46.3% after 25 days of forming biocover. However, due to hardening process efficiency dropped to 4.6%. After overturn of the surface soil, the rate subsequently increased to 17.9%, with an evaluated average of 12.5%.

The increase in carbon stock and sustainability of crop production are the main challenges in agricultural fields relevant to climate change. Methane is the most important greenhouse gas emitted from paddy fields. This study was conducted to investigate the effects of tillage and cultivation methods on methane emissions in rice production in 2014 and 2015. Different combinations of tillage and cultivation were implemented, including conventional tillage-transplanting (T-T), tillage-wet hill seeding (T-W), minimum tillage-dry seeding (MT-D), and no-tillage-dry seeding (NT-D). The amount of methane emitted was the highest in T-T treatment. In MT-D and NT-D treatments, methane emissions were significantly decreased by 77%, compared with that in T-T treatment. Conversely, the soil total carbon (STC) content was higher in MT-D and NT-D plots than in tillage plots. In both years, methane emissions were highly correlated with the dry weight of rice (R 2 = 0.62~0.96), although the cumulative emissions during the rice growing period was higher in 2014 than in 2015. T-T treatment showed the highest R 2 (0.93) among the four treatments. Rice grain yields did not significantly differ with the tillage and cultivation methods used. These results suggest that NT-D practice in rice production could reduce the methane emissions and increase the STC content without loss in grain yield.

The Intergovernmental Panel on Climate Change (IPCC) recommended the first order decay (FOD) model for estimating methane emissions from solid waste landfills. However, selecting appropriate parameter is a major challenge in methane emission modeling. The degradable organic carbon (DOC) and the fraction of degradable organic carbon which decomposes (DOCF) are the two primary parameters in the methane generation potential (L0). The DOC is the amount of organic carbon that can be decomposed by biochemical reactions in microorganisms. Chemical analysis methods are currently available to measure the DOC including using total organic carbon and element analysis methods. However, chemical analysis methods are not appropriate for determination of the DOC, which indicated that the DOC should be measured by biochemical tests. In addition, these methods should consider a fossil carbon content that needs a complex and high cost of analysis. The DOCF is an estimate of the fraction of carbon that is ultimately degraded and released from landfills. However, no methodology is provided for determination of the DOCF in landfills. Therefore, the purpose of this study was to suggest methodologies for the determination of DOC and DOCF in solid waste landfills. A biochemical methane potential (BMP) test could be used to calculate the DOC because the BMP represents an upper limit on the methane potential of a waste, which corresponds to a maximal amount of degraded organic carbon. The calculation was based on the assumption that the DOCF is 100%. In this study, two methodologies were suggested to determine the DOCF in landfills. The first one uses a new equation (DOCF = 2.76W-0.44) with moisture content in the landfill that actual methane flux data are unavailable. Moisture content is a major ecological parameter on the anaerobic biodegradability of the solid waste in the landfill. Another methodology is to use L0,Landfill/L0,BMP ratio. The L0,Landfill could be determined by a regression analysis if methane flux data were available.