Direct Measurement of Greenhouse Gas Emission Rates From Manure Management in Different Livestock Production Systems in Cameroon

Direct measurements of greenhouse gas emissions from the increasingly intensified African livestock production are important to assess locally available mitigation strategies. As such, measurements were conducted from March to June using static flux chambers to quantify the emission rates of CH4, N2O, and CO2 from manure in poultry and pig production systems in Cameroon. Emissions were measured from two layer barns, two pig facilities, six broiler farms, and one farm with Brahman birds. Mean emission factors inside two layer barns were 0.06–0.21 and 602–958 mg animal−1 h−1 for CH4 and CO2, respectively, and 21–112 µg animal−1 h−1 for N2O. Mean emission factors inside four broiler barns with wood shavings as bedding material were 0.31–1.22 and 355–1884 mg animal−1 h−1 for CH4 and CO2, respectively, and 2.33–1052 µg animal−1 h−1 for N2O. Broiler N2O emissions were 971.38 ± 250.23 and 26.14 ± 30.27 µg animal−1 h−1 from manure underneath a meshed floor barn and a shelter with bare soil, respectively. Emissions from a storage tank with wastewater from a piggery were 8.30 ± 7.36 and 40.41 ± 5.54 mg m−2 min−1 for CH4 and CO2, respectively, and 2.80 ± 1.67 µg m−2 min−1 for N2O. Mean emissions from two outdoor storages of a mixture of poultry and pig manure were 0.76–0.9 and 69–136 mg m−2 min−1 for CH4 and CO2, respectively, and 10–15 µg m−2 min−1 for N2O. Emissions depended highly on manure production and management systems. CH4 emissions were lower from poultry compared to pig manure. Younger layers emitted higher CH4 compared to older layer hens. CH4 emissions were higher from slurry compared to solid manure, whereas N2O emissions were higher from solid compared to slurry manure storages. These findings indicate that mitigation strategies for greenhouse gas emissions should depend not only on the type of gases and manure management systems but also on the animal types and their ages.