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

Abstract

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 CO_2, 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.