Livestock production contributes to releasing methane into the atmosphere. Liquid manure management offers significant opportunities to reduce these emissions. A better understanding of the factors controlling methane emissions from manure is necessary to select effective mitigation strategies. Our study aimed to identify the influence of storage temperature and the associated change in chemical composition on methane emissions from dairy and fattening pig manure. Storage temperature affects microbial activity and induces changes in chemical composition that are key influences in methane emissions. Dairy and fattening pig manure samples were stored at five different temperatures (5–25 °C) for 90 days in a laboratory-scale experiment to measure the methane production. The chemical composition of the slurry samples was analyzed, and the biochemical methane potential (BMP) tests were performed before and after storage. For pig manure stored at 25 °C and 20 °C, methane emissions accounted for 69.3% and 50.3% of the BMP, respectively. Maximum methane emissions for dairy slurry were observed at 25 °C but remained at a low level. Analyses of the accumulation of volatile fatty acids (VFAs) during storage are presented in few studies, this work revealed a potential inhibition of methane production, where the accumulation of VFAs was most elevated in samples stored at 20 °C and 25 °C. This partly counteracted the increase in methane emissions expected from the higher temperatures. The degree of VFA and dissociated fatty acids accumulation in dairy cattle slurry should be assessed for more accurate estimations of methane emissions from slurry stores.
Forests and agroforestry systems in the tropics play a decisive role in global carbon fixation strategies. The amount and type of coverage, along with the specific land use and land use change in a given area, determines whether carbon is stored or released into the atmosphere. The aim of this study was to evaluate the traditional silvopastoral systems (TSPS) through quantitative analysis of biomass and soil carbon storage whilst simultaneously qualitatively determining the ecological structure in terms of tree richness and diversity. The study was carried out in Matigua ´s, a sub-humid tropical region of Nicaragua, on five land use types: shrubland; intervened secondary forest; pasture with high tree density; pasture with low tree density and degraded pasture. Biomass carbon was estimated by allometric equations and soil organic carbon was evaluated at four depths (0-10, 10-20, 20-40 and 40-100 cm). Of the land uses studied, shrubland had the highest diversity. The biomass carbon ranged from 1.9 to 13.2 t C ha -1 for degraded pasture and intervened secondary forest, respectively. The highest soil organic carbon (SOC) storage at 1 m depth was for intervened secondary forest (163 t C ha -1 ), whereas degraded pastures had the lowest value (76 t C ha -1 ). Since SOC was the largest pool of total carbon in all cases, it should be evaluated down to a depth of at least 1 m. Increasing tree coverage in degraded and low-tree density pastures can contribute not only to enhance carbon sequestration but also to restore degraded lands in livestock landscapes.
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