Perspectives on peak liquid manure temperature with implications for methane emissions.

Manure temperature prediction for slurry storage in Sweden: Model validation including effects of shading, snow cover and mixing

Greenhouse gas emissions from stored liquid swine manure in a cold climate

HighlightsEvaporation from clear water, manure, and separated liquid manure was 4.6 mm d-1 on average.Straw, foam, geotextile, and roof covers decreased evaporation by 54%, 53%, 31%, and 21%, respectively.Albedo was highest for floating foam covers and lowest for metal roof covers.Straw, foam, and geotextile increased manure temperature compared to uncovered manure. ABSTRACT. Evaporation is a key component of the surface energy budget of liquid manure. Models rely on accurate energy budgets to predict manure temperature, which in turn is used to model temperature-dependent greenhouse gas emissions from liquid manure storages. Due to lack of data, it has been assumed that liquid manure has similar evaporative properties to water; however, this assumption may be inaccurate. Many factors, including manure crusting, covers, and turbidity, are all likely to affect the surface energy budget and the evaporation rate. This experiment investigated the differences in evaporation between eight treatments, including water, dyed water, raw and separated liquid manure, and four commonly used covers (straw, geotextile, foam, and roof), by measuring weekly evaporation. Albedo, surface temperatures, and internal temperatures were also measured to determine treatment effects. Over the 10-week study, no significant difference was found between the evaporation rates of water, raw manure, and separated liquid manure, with an average rate of 4.6 mm d-1. Notably, the raw manure did not form a consistent surface crust, which may explain the similarities in evaporation rates in this study and is unlikely to represent manure with a crust. Overall, covers significantly decreased evaporative losses by between 21% and 54% compared to uncovered raw manure. Average evaporation rates of the covered treatments were 1.9 mm d-1 for straw cover, 2.0 mm d-1 for foam cover, 2.9 mm d-1 for geotextile cover, and 3.4 mm d-1 under a roof cover. Similarities between each treatment and water as well as between the four covered treatments and the uncovered raw manure were found using linear regression on weekly evaporation. Generally, the uncovered treatments were more similar and could be predicted (high R2) by multiple linear regression with environmental variables, while the covered treatments differed more and were not as well predicted (lower R2). Results from this study can help adjust evaporation rates in biophysical models to improve estimates of manure temperature, tank holding capacity, and emission predictions. Keywords: Evaporation, Dairy manure, Liquid manure, Manure covers, Manure management.

Greenhouse gas emissions from liquid livestock manure storage significantly contribute to global warming. Accurate farm-scale models are essential for predicting these emissions and evaluating manure management strategies, but they rely on multiple parameters describing carbon loss dynamics. Surface respiration may significantly influence carbon loss and methane emission, yet it is not explicitly included in current models. We conducted experiments to measure pig manure surface respiration rate and its effect on organic matter degradation and methane and carbon dioxide emissions. Manure was incubated for 283 days at 10°C or 20°C under aerobic or anaerobic conditions, while measuring methane and carbon dioxide emission. This was followed by anaerobic digestion at 38°C. Surface respiration reduced the organic matter content, and the effect was temperature dependent. Methane emission was not affected by surface respiration, suggesting that substrate availability was not rate-limiting for methanogenesis. Surface respiration rates were 18.1±3.5g CO2 m-2 day-1 at 10°C and 37.1±13.1g CO2 m-2 day-1 at 20°C (mean±standard deviation) and were consistent with microsensor measurements of oxygen consumption in different manure surfaces. Based on these results, temperature- and surface area-dependent respiration was incorporated in the existing anaerobic biodegradation model (ABM). Simulations showed that surface respiration accounts for 29% of carbon losses in a typical pig house and 8% for outdoor storage. Developing and refining algorithms for diverse carbon transformations, such as surface respiration, is crucial for evaluating the potential for methane emission and identification of variables that control emissions at the farm scale.

More than a quarter of anthropogenic global warming has been attributed to methane growth in the atmosphere. Landfills account for 17% of estimated methane emissions in the United States of America (USA), according to the Environmental Protection Agency (EPA), but studies show that many landfills emit more than reported. We developed a novel method to calculate monthly methane emissions from an active landfill using atmospheric methane mixing ratios observed from a single tower in New Jersey, USA. The tower method provides two and a half years of semicontinuous measurements and therefore observes more of the variability of methane emissions and lacks the sampling bias present in other methods. Time-specific comparison of tower-based methane emissions against those observed from summertime aircraft sampling and year-round mobile ground-based platforms showed good agreement. Estimated methane emissions for 2023 were five times greater than those reported to the EPA. We observed a strong seasonality in methane emissions, with a peak in the winter and a minimum in the summer. This seasonal cycle was driven by a strong negative dependence on air temperature and the change in atmospheric pressure. Our results highlight the importance of observations in nonideal weather conditions (such as declining pressure and near-freezing temperatures) when methane emissions are largest. We suggest that this methodology could be applied to other suitable landfills to improve estimates of methane emissions.

Estimation of methane and nitrous oxide emissions from paddy fields in Taiwan

National inventories of methane (CH4 ) emission from manure management are based on guidelines from the Intergovernmental Panel on Climate Change using country-specific emission factors. These calculations must be simple and, consequently, the effects of management practices and environmental conditions are only crudely represented in the calculations. The intention of this review is to develop a detailed understanding necessary for developing accurate models for calculating CH4 emission from liquid manure, with particular focus on the microbiological conversion of organic matter to CH4 . Themes discussed are (a) the liquid manure environment; (b) methane production processes from a modeling perspective; (c) development and adaptation of methanogenic communities; (d) mass and electron conservation; (e) steps limiting CH4 production; (f) inhibition of methanogens; (g) temperature effects on CH4 production; and (h) limits of existing estimation approaches. We conclude that a model must include calculation of microbial response to variations in manure temperature, substrate availability and age, and management system, because these variables substantially affect CH4 production. Methane production can be reduced by manipulating key variables through management procedures, and the effects may be taken into account by including a microbial component in the model. When developing new calculation procedures, it is important to include reasonably accurate algorithms of microbial adaptation. This review presents concepts for these calculations and ideas for how these may be carried out. A need for better quantification of hydrolysis kinetics is identified, and the importance of short- and long-term microbial adaptation is highlighted.

The objective of the study was to determine enteric methane emissions using the sulfur hexafluoride (SF6) technique and comparing with The Intergovernmental Panel on Climate Change (IPCC) methodology in lactating cows (LC) and dry cows (DC) in the Peruvian highlands. Enteric methane (CH4) emissions were measured on 5 LC and 6 DC Brown Swiss in a grazing system without concentrate. Forages samples were collected and analyzed for dry matter, crude protein, and neutral detergent fiber. Milk samples were collected and analyzed for fat, crude protein, and lactose to estimate energy-corrected milk. Animal intakes were measured using the external marker titanium dioxide (production of feces) and crude protein in feces (organic digestibility of the feed) and estimated by using performance data. The enteric methane emissions of LC were higher than methane emissions of DC (325 and 266g CH4/cow/day for LC and DC, respectively (P < 0.001)). Methane emissions were 358.5g CH4/day by SF6 technique and 291.6g CH4/day by IPCC methodology for LC and 337.4g CH4/day by SF6 technique and 195.8g CH4/day by IPCC methodology for DC. Methane yields measured by SF6 were higher than methane yields estimated by IPCC methodology (29g CH4/kg DM and 22g CH4/kg DM using SF6 technique and IPCC methodology, respectively (P < 0.001)). Methane yields were differently for all expressions by physiological stage and method. The methane conversion factor (Ym) was 9.7% for LC and 9.6% for DC. Methane intensities were similar by method (P > 0.05). It was concluded that IPCC's methodology underestimate the CH4 emissions of dairy systems in the Peruvian Andes; therefore, in order to obtain precise Ym, direct measurements of enteric CH4 in the different regions of Peruvian highlands are required.

BackgroundLivestock play an important role in carbon cycling through consumption of biomass and emissions of methane. Recent research suggests that existing bottom-up inventories of livestock methane emissions in the US, such as those made using 2006 IPCC Tier 1 livestock emissions factors, are too low. This may be due to outdated information used to develop these emissions factors. In this study, we update information for cattle and swine by region, based on reported recent changes in animal body mass, feed quality and quantity, milk productivity, and management of animals and manure. We then use this updated information to calculate new livestock methane emissions factors for enteric fermentation in cattle, and for manure management in cattle and swine.ResultsUsing the new emissions factors, we estimate global livestock emissions of 119.1 ± 18.2 Tg methane in 2011; this quantity is 11% greater than that obtained using the IPCC 2006 emissions factors, encompassing an 8.4% increase in enteric fermentation methane, a 36.7% increase in manure management methane, and notable variability among regions and sources. For example, revised manure management methane emissions for 2011 in the US increased by 71.8%. For years through 2013, we present (a) annual livestock methane emissions, (b) complete annual livestock carbon budgets, including carbon dioxide emissions, and (c) spatial distributions of livestock methane and other carbon fluxes, downscaled to 0.05 × 0.05 degree resolution.ConclusionsOur revised bottom-up estimates of global livestock methane emissions are comparable to recently reported top-down global estimates for recent years, and account for a significant part of the increase in annual methane emissions since 2007. Our results suggest that livestock methane emissions, while not the dominant overall source of global methane emissions, may be a major contributor to the observed annual emissions increases over the 2000s to 2010s. Differences at regional and local scales may help distinguish livestock methane emissions from those of other sectors in future top-down studies. The revised estimates allow improved reconciliation of top-down and bottom-up estimates of methane emissions, will facilitate the development and evaluation of Earth system models, and provide consistent regional and global Tier 1 estimates for environmental assessments.

Objective: To determine the in vitro digestibility and gas production, and to estimate the methane emissions from Kikuyu grass pastures, and Kikuyu grass overseeded with rye. Design/methodology/approach: Two pastures were assessed. One was the subtropical grass Kikuyu Cenchrus clandestinus) (KY), and the other was Kikuyu grass plus overseeding with rye (Secale cereale) (KYCEN), both associated with white clover (Trifolium repens cv. Ladino). Sample collection was in June and July 2021. In vitro digestibility of dry matter (MS), organic matter (MO), and Neutral Detergent Fibre (FDN), as well as the methane emissions were estimated. The in vitro digestibility and gas production variables were analysed with a split-plot experimental design, and the methane emission variables were analysed with a doble cross-over design. Results: There were no significant differences between treatments for dry matter (MS), organic matter (MO) or Neutral Detergent Fibre (FDN) in vitro digestibility, nor in methane emissions (P&gt;0.05). Limitations on study/implications: The in vitro assessment of digestibility, gas production and the estimation of methane emissions of Kikuyu grass pastures and Kikuyu plus rye enable the implementation of feeding strategies for small-scale livestock production systems that do not only benefit the farmers but also the environment. Findings/conclusions: It is concluded that Kikuyu grass pastures and Kikuyu with rye are a viable feeding option for small-scale dairy systems.

Methane emissions from a dairy feedlot during the fall and winter seasons in Northern China

Since livestock account for most of Türkiye’s agricultural greenhouse gas emissions, strategies for estimating livestock emissions must be developed. Methane emissions per animal category were estimated in this study using the Intergovernmental Panel on Climate Change (IPCC) Tier 2 method for enteric and manure methane (CH4) emissions in two sheep breeds (Akkaraman and Anatolian Merino) and three goat breeds (Hairy, Angora, Saanen) raised in Ankara province, Türkiye. Average enteric CH4 emission factor (EF) was 9.61 kg CH4 head-1 yr-1, with the highest value of 10.86 kg CH4 head-1 yr-1 in Hairy goats, and lowest 8.55 kg CH4 head-1 yr-1 in Anatolian Merino. Estimated gross energy (GE) was highest in Hairy goats (30.10 MJ head-1 day-1), and lowest in Anatolian Merino (21.73 MJ head-1 day-1). Average dry matter intake (DMI) was 1.40 kg DM head-1 day-1. The total average volatile solids (VS) excretion was estimated at 0.95 kg DM head-1 yr-1, and the average methane emission factor (EF) for animal manure was 0.46 kg CH4 head-1 yr-1. Total mean VS estimate was twice as much as the IPCC default values, and the CH4 EF for animal manure was higher than the IPCC default values. The current study's estimates will be helpful in the creation of the national methane inventory. In case more detailed data are collected to improve population data, subcategories may be expanded, and subgroups may vary by region.

Objectives/Scope This study was based on estimation and quantification of fugitive methane emissions from a 170,000 km gas distribution network in Italy, following the OGMP 2.0 Standard. Commissioned by a major gas company, the project covered the period 2021-2023. The key objectives of the activity carried out was to report methane emissions following the OGMP 2.0 framework, develop an advanced emissions estimation model and create a roadmap for achieving the "Gold Standard." This study highlights the critical issues encountered in selecting the appropriate measurement technologies and data processing methodologies and analyzes the applied solutions, also identifying possible ideas for future improvement. Methods/Procedures/Process The methodology involved the analysis of technical documentation and client data to report methane emissions following the OGMP 2.0 Level 3. An advanced estimation model was developed based on field data from a "site-level provider" to determine emission factors for distribution pipelines. Field campaigns using "bagging method" and portable gas detectors were conducted to quantify emissions, ensuring compliance with Level 3 standards and results compared with vehicle-based leaks detection (site Level monitoring). Results/Observations/Conclusions The study highlighted the challenges of monitoring methane emissions in gas distribution networks, where fugitive leaks can also be due to corrosion phenomena of the pipelines. The results of this study represented an advancement in the precise quantification and management of methane emissions within the client's extensive gas distribution network. The results concerned three different aspects: emission estimates methodology, comparison of measurement methods/technologies and statistical analysis. The correlation of the results obtained for all the mentioned aspects provided useful insights into how to apply technologies, the reliability of data aggregation, and how to potentially improve in the future with dedicated experimental studies. Novel information This study offered novel contributions by developing a tailored analytical model for methane emissions in a complex gas distribution network, applying OGMP 2.0 standards to a real-world scenario in Italy. It integrated a comparative analysis between different technologies, providing valuable insights. The findings emphasized the importance of precise quantification, continuous improvement, and innovation in methane emissions management, supporting global efforts to mitigate climate change impacts.

Temperature, but not submersion or orientation, influences the rate of sulphur hexafluoride release from permeation tubes used for estimation of ruminant methane emissions

Swine manure is kept in outdoor storage facilities until it is applied to cropland. Anaerobic conditions facilitate microbial methane (CH4 ) production at a rate that depends on temperature. Manure CH4 emissions can be the largest contributor to the carbon footprint of pork production. Despite the importance of CH4 , its actual emissions in cold temperate climates are highly uncertain. This study measured emissions from a single-cell earthen manure storage facility at a commercial swine farm near Brandon, Manitoba, Canada, for 3 yr. Complimentary laboratory measurements were done to assess CH4 potential (B0 ). The manure storage regularly received manure from the barn and was only emptied in October. In the summer, manure temperature was usually lower than the air temperature, with the manure temperature (averaged across depths) warming to between 15 and 18.5°C for only 9wk. Emissions of CH4 were low, with the CH4 conversion factor being between 3.0 and 11.0%, depending on the year (using the IPCC 2019 default B0 ). Scaled by the number of swine reaching market weight (125kg) each year, CH4 emissions were between 250 and 902g CH4 animal-1 . Laboratory measurements of CH4 production potential scaled by VS were 335ml CH4 g-1 VS at 37°C, perhaps lower than the IPCC 2019 default value due to barley (Hordeum vulgareL.) in the ration and degradation in the under-barn pit prior to transfer outdoors. Taken together, the low manure temperatures, short warm season, and barley in the ration suggest that emissions from swine manure in cold climates like western Canada are considerably lower than previously estimated based on default factors.