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Current agricultural practices in regards to storage of manure come with a significant GHG contribution, due, to a big extent, to CH 4 emissions. For example, in Denmark, the agricultural sector is responsible for about 11.1 metric tons of CO 2 equivalents; only about 0.2 metric tons come directly from CO 2 , while 6.0 tons come from CH 4. The present study aims at evaluating and comparing two methods based on their effect on suppressing CH 4 emissions during storage as well as on preserving and enhancing CH 4 yield in a subsequent anaerobic digestion step: the commonly applied acidification with H 2 SO 4 as acidifying agent and thermal treatment at the mild temperatures of 70 and 90 °C (pasteurization). Although both treatments effectively suppressed CH 4 emissions during storage, they exhibited a significant difference in preserving and/or enhancing the CH 4 potential of manure. Specifically, thermal treatment resulted in 16–35% enhancement of CH 4 potential, while acidification resulted in decreasing the CH 4 yield by 6–23% compared to non-treated manure. Further investigation showed that storage itself positively affected the CH 4 potential of treated manure in a subsequent anaerobic digestion step; this was attributed to microbial activity other than biomethanation during storage. In overall and based on the results obtained regarding suppression of CH 4 emissions during storage as well as CH 4 potential enhancement, pasteurization at the temperatures tested is a promising alternative to the broadly applied acidification of manure. [Display omitted] • Pasteurization & acidification compared against CH 4 emissions reduction. • Pasteurization and acidification suppressed CH 4 emissions during storage by 95–99%. • Pasteurization enhanced methane potential during anaerobic digestion by 16–35%. • Acidification diminished methane potential during anaerobic digestion by 6–23%. • Pasteurization is promising alternative to acidification with H 2 SO 4 prior to storage. [ABSTRACT FROM AUTHOR]

Animal manure handling is an essential but challenging part of Europe's intensive agriculture. To safeguard the environment and facilitate sustainable livestock production, lower-impact manure management technologies need to be identified, evaluated and implemented. Slurry acidification has been developed to address some of the environmental challenges faced by pig farmers, such as methane and ammonia emissions, that contribute to environmental impacts such as climate change, terrestrial acidification and air fine particulate matter formation. However, the efficiency of this technology has been found to depend on local environmental and regulatory conditions. The current study compared two slurry treatment options (no treatment versus slurry acidification in storage tanks) under the climatic, agronomic and legislative conditions found in Denmark, the Netherlands and Spain using Life Cycle Assessment (LCA). Data for the LCA model was collected from various sources and emissions following field application and crop yields were simulated over a 100-year period using the Daisy agricultural model. To address the uncertainty in LCA modelling, parameter analyses and Monte Carlo simulations with 1000 iterations were conducted followed by pairwise statistical tests. The results indicated that slurry acidification reduces the impact in all countries in impact categories mostly related to direct emissions from agriculture, such as methane and ammonia. For impact categories related to the provision of materials and energy to the farm, acidification increased the impacts in some cases. Additional requirements for lime application to counteract potential soil acidification did not result in significant changes in the performance of slurry acidification. The sulphur in the applied acid as an alternative to mineral S fertiliser can in some cases reduce the environmental impact of slurry acidification, but should not be advertised as doing so per se. Introducing stricter P application limits would seem to be the preferred option compared with slurry acidification in the Netherlands, while the opposite appeared true for Denmark. [Display omitted] • Analysis of pig slurry acidification using LCA. • Environmental impacts of slurry acidification differ between European countries. • Acidification reduces farm-related environmental impacts. • Trade-off between reduced on-farm and increased off-farm impacts. [ABSTRACT FROM AUTHOR]

In Denmark, agriculture is the largest source of anthropogenic methane emissions (81%), mainly from cattle (dairy and beef) farms. Whole-farm methane emissions were quantified at nine Danish cattle farms, using the tracer gas dispersion method. Five to six measurement campaigns were carried out at each farm, covering a full year. Of the nine cattle farms, seven were home to dairy cows and two to beef cattle. The farms represented typical breeds, housing and management systems used in Denmark. Whole-farm methane emission rates ranged from 0.7 to 28 kg h−1, with the highest measurements seen at locations with the highest number of animals. Emissions tended to be higher from August to October, due to elevated temperatures and high amounts of stored manure during this period of the year. The average emission factor (EF) for dairy cow farms was 26 ± 8.5 g Livestock Unit (LU)−1 h−1, whereas it was 16 ± 4.1 LU−1 h−1 for beef cattle farms, i.e. 38% lower for the latter. The use of deep litter house management explained some of the differences found in the EFs for dairy cows. Methane emission rates estimated using IPCC models and national guidelines tended, on average for all farms and measurements, to be underestimated by 35% in comparison with the measured methane emissions, for all models and farms. The results suggest that future improvements to inventory models should focus on enteric methane emissions from beef cattle and manure methane emissions for both dairy cows and beef cattle, especially from deep litter management. • Whole-farm methane emissions were quantified using the tracer dispersion method. • Methane emissions from 0.7 to 28 kg h−1 were quantified at nine cattle farms. • Methane emissions tended to be higher during late summer/autumn. • Emission factors averaged 26 g LU−1 h−1 for dairy cow 16 g LU−1h−1 for beef cattle. • Inventory estimations were on average 35% lower than farm-scale measured emissions. [ABSTRACT FROM AUTHOR]

This study investigated whole-farm methane emissions from five Danish pig farms with different manure management practices and compared measured emission rates to international and national greenhouse gas inventory emission models. Methane emissions were quantified by using the tracer gas dispersion method. Farms were measured between five and eight times throughout a whole year. One of the farms housed sows and weaners (P1) and the others focused on fattening pigs (P2-P5). The farms had different manure treatment practices including biogasification (P3), acidification (P4-P5) and no manure treatment (liquid slurry) (P1-P2). Quantified methane emissions ranged from 0.2 to 20 kg/h and the highest rates were seen at the farms with fattening pigs and with no manure treatment (P2), while the lowest emissions were detected at farms with manure acidification (P4 and P5). Average methane emission factors (EFs), normalised based on livestock units, were 14 ± 6, 18 ± 9, 8 ± 7, 2 ± 1 and 1 ± 1 g/LU/h, for P1, P2, P3, P4 and P5, respectively. Emissions from fattening pig farms with biogasification (P3) and acidification (P4-P5) facilities were 55% and 91-93% lower, respectively, than from farm with no manure treatment (P2). Inventory models underestimated farm-measured methane emissions on average by 51%, across all models and farms, with the Danish model performing the worst (underestimation of 64%). A revision of model parameters related to manure emissions, such as the estimation of volatile solids excreted and methane conversion factor parameters, could improve model output, although more data needs to be collected to strengthen the conclusions. As one of the first studies assessing whole-pig farm emissions, the results showed the potential of the applied measuring method to identify mitigation strategy efficiencies and highlighted the necessity to investigate inventory model accuracy., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The potential of modifications in the housing conditions and manure management to reduce the environmental impact of a European pig production system were evaluated. The study was carried out using a cradle-to-farm gate life cycle assessment (LCA), with a functional unit of 1 kg of live weight pig at farm gate. The study used Danish pig systems as a case in point, with data provided by the Danish Pig Research Centre (SEGES). Potential environmental impact hotspots at pig housing and manure management were identified through a local sensitivity analysis. A set of pig housing and manure management alternative scenarios were analysed using parallel Monte Carlo simulations, to quantify interactions between these two components of the system. The manure management scenarios were slurry acidification, screw-press slurry separation and centralised anaerobic digestion of slurry. The pig housing scenarios were constructed around variations of the following factors: i) level of barn insulation, ii) in-barn temperature, iii) ventilation efficiency, iv) level of slurry dilution and v) frequency of slurry removal from barn pits. Anaerobic digestion significantly reduced the environmental impact for Non-Renewable Resource Use (−34.1% compared to baseline), Non-Renewable Energy Use (−40.1%) and Global Warming Potential (−9.20%). Slurry acidification led to significant reductions in Acidification (−28.1%) and Eutrophication Potential (−14.2%). Slurry separation significantly reduced only Non-Renewable Energy Use (−2.26%). The scenario analysis showed that the environmental performance of all manure management alternatives was affected by variations in all housing related factors, except for in-barn temperature. The largest improvement in environmental performance of the manure management component was achieved for Acidification Potential (−5.51%) by increasing the level of slurry dilution under baseline manure management conditions. Slurry acidification was the least sensitive manure management alternative to modifications in pig housing. Both manure management and housing conditions have the potential to reduce the environmental impact of pig systems in Europe. • Environmental impact hotspots associated with pig housing were identified. • Interactions between housing and manure management (MM) were quantified. • Modifications in housing significantly affected the MM environmental performance. • Increased slurry dilution caused the largest improvement for baseline MM. • Slurry acidification was the most robust scenario to modifications in pig housing. [ABSTRACT FROM AUTHOR]