Assessing greenhouse gas emissions from outdoor cattle sleeping areas in Cameroon

Cattle production is an important source of greenhouse gas (GHG) emissions which affects the environment. While emissions have mostly been quantified from barns and manure storage facilities, little information is available on emissions from outdoor sleeping areas, especially in Africa. This project was carried out in two beef cattle farms (Banshe and Menteh) in Cameroon, with the aim of quantifying GHG emissions from the outdoor sleeping areas. The sleeping areas were fenced with planks and the floor was bare soil covered mainly with cattle manure. Gas emission rates were measured when the cattle were on pasture using 2 non-steady state flux chambers during the wet season for 1 week in each farm. Manure dry matter, determined using method 1648 of the U.S. Environmental Protection Agency, was in the range of 28-38% while the volatile solid content was in the range of 41-57%. Emission hotspots and hot moments were observed with large variations in time and location. The methane (CH4) emissions were 4.04 +/- 4.3 and 1.85 +/- 1.7 mg m(-2) min(-1) in Banshe and Menteh, respectively. The nitrous oxide (N2O) emissions were 0.008 +/- 0.02 and 0.049 +/- 0.06 mg m(-2) min(-1) in Banshe and Menteh, respectively. The sleeping area with high CH4 emissions was associated with low N2O emissions and vice versa. The carbon dioxide (CO2) to CH4 emission ratios were high; similar to 7 for Banshe and similar to 15 for Menteh, indicating more aerobic conditions. The total GHG (CH4 + N2O) emission rates were 139.7 and 77.5 mg CO(2)e m(-2) min(-1) in Banshe and Menteh, respectively. This indicated that CH 4 contributed 98 and 81% of the total GHG in Banshe and Menteh, respectively. This shows that mitigation strategies should be geared more towards CH4 in the sleeping areas in this study during the wet season. The GHG emission factors estimated in this research were the first of its kind in Cameroon, and can be used as a basis for planning management practices that mitigate emissions. (C) 2019 The Authors. PublishedbyElsevier B.V. on behalf of African Institute of Mathematical Sciences / Next Einstein Initiative.