Provincial cattle carbon emissions from enteric fermentation and manure management in South Africa

Abstract

Livestock is a major producer of agricultural greenhouse gas emissions in South Africa. Cattle methane (CH₄) from enteric fermentation is the main source of the emissions. However, due to shortage of information to guide agricultural mitigation plans in the country, the main objective of this study is to investigate causal factors of the emissions from cattle in all nine national provinces. This study calculates provincial CH₄ emission factors and factors (i.e. nitrogen excretion rate and average annual nitrogen excretion per animal) required for nitrous oxide (N₂O) emissions from cattle manure management. The study further uses these factors and other values obtained from the literature to calculate cattle CH₄ emissions from enteric fermentation and manure management. It also provides similar N₂O emissions from manure management as well as urine and dung deposited on the pasture, range and paddock. The emissions are calculated for each cattle type: commercial dairy, commercial beef, subsistence and feedlot cattle. Cattle in South Africa produced a total of 35.37 million tonnes (Mt) of carbon dioxide equivalent (CO₂e) emissions in 2019, inclusive of emissions from pasture, range and paddock. Methane from enteric fermentation accounts for 64.54% of the total emissions followed by emissions from pasture, range and paddock (27.66%). Manure management contributes 4.34% of N₂O to the total emissions while this source also produces 3.45% of CH₄ emissions. Commercial beef is responsible for 50.21% of the total emissions, followed by subsistence beef (36.72%), commercial dairy (10.52%) and feedlot cattle (2.52%). The Eastern Cape province is the highest producer of cattle emissions with 8.66 Mt CO₂e, a quarter of the emissions. It is followed by KwaZulu-Natal (7.14 Mt CO₂e, 20%) and the Free State (5.65 Mt CO₂e, 16%). Gauteng province is responsible for the lowest producer of the emissions with 0.71 Mt CO₂e (2%) of the total. South Africa's emission factors are higher than values for Africa, indicating importance of developing national factors to avoid uncertainties in emissions. As a result of national landscape and environmental conditions, the eastern provinces of the country are major sources of cattle emissions in the country.

Keywords: Enteric fermentation; Manure management; Methane; Nitrous oxide; Pasture; Range and paddock.