A comparative analysis of livestock methane emissions across Plain and Haor ecosystems in Bangladesh

Methane (CH₄) emissions from livestock are a critical component of Bangladesh’s agricultural greenhouse gas inventory, yet regional contrasts in emission drivers remain poorly quantified. This study provides a comparative assessment of CH₄ emissions from livestock and manure management across two distinct agro ecological zones: the Plain Land (Mithapukur) and the Haor/Wetland ecosystems (Austagram, Itna, Mitamoin). Using the IPCC Tier 2 methodology, primary data on feed composition, volatile solids (VS) excretion and manure storage practices were analyzed to generate region specific emission factors. Results revealed stark differences in emission intensity. The Plain Land, dominated by pit storage (99.82% of farms), produced 47,095.92 kg CH₄/year, with an average emission intensity of 117.74 kg/animal/year and mean pit-based emission of 329.83 kg/year. In contrast, the Haor/Wetland, where pit storage accounted for 61.96% and heap storage for 38.04%, generated only 6,104.15 kg CH₄/year (pit: 3,781.96 kg/year, heap: 2,322.19 kg/year), with an emission intensity of 5.35 kg/animal/year and mean heap based emission of 11.14 kg/year. Enteric fermentation contributed substantially, with buffalo emitting 49.9 kg CH₄/head/year, HF cross cattle 28.5 kg/year and local cattle 21.6 kg/year, reflecting differences in body weight and feed intake. Regression analysis confirmed stronger methanogenic efficiency in Plain Land (β = 0.1039, R² = 0.999) compared to Haor (β = 0.0915, R² = 0.864). Although seasonal inundation in Haor elevated per-animal emissions by 23–27%, Plain Land’s higher volatile solid excretion (5.12 vs. 4.35 kg/day), greater concentrate feeding and larger herd density amplified cumulative emissions. These findings underscore that CH₄ emissions are driven by manure management systems, feed composition and ecological constraints. Region specific mitigation is essential: biogas recovery and diversified manure use in Plain Land, flood-resilient composting in Haor, alongside improved feed digestibility, covered storage, manure crop integration and grazing management to reduce both manure and enteric CH₄ emissions nationwide.