Agricultural Research Council - Institute for Soil, Climate and Water, Private Bag X79, Pretoria, 0001, South Africa; Department of Geography, University of the Free State, QwaQwa Campus, Private Bag X13, Phuthadithjaba, 9866, South Africa; Zutari, Riverwalk Office Park, 41 Matroosberg Road, Ashlea Gardens Extension 6, Pretoria, South Africa.
Agricultural Research Council - Institute for Soil, Climate and Water, Private Bag X79, Pretoria, 0001, South Africa; Risk and Vulnerability Assessment Centre, University of Limpopo, Private Bag X1106, Sovenga, 0727, South Africa.
Environ Res. 2021 Apr;195:110833. doi: 10.1016/j.envres.2021.110833. Epub 2021 Feb 3.
Livestock is a major producer of agricultural greenhouse gas emissions in South Africa. Cattle methane (CH) 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 CH emission factors and factors (i.e. nitrogen excretion rate and average annual nitrogen excretion per animal) required for nitrous oxide (NO) emissions from cattle manure management. The study further uses these factors and other values obtained from the literature to calculate cattle CH emissions from enteric fermentation and manure management. It also provides similar NO 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 (COe) 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 NO to the total emissions while this source also produces 3.45% of CH 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 COe, a quarter of the emissions. It is followed by KwaZulu-Natal (7.14 Mt COe, 20%) and the Free State (5.65 Mt COe, 16%). Gauteng province is responsible for the lowest producer of the emissions with 0.71 Mt COe (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.
牲畜是南非农业温室气体排放的主要来源。反刍动物肠道发酵产生的甲烷（CH）是排放的主要来源。然而，由于缺乏信息来指导该国的农业减排计划，本研究的主要目的是调查该国所有九个省份牛只排放的因果因素。本研究计算了省级 CH 排放因子以及牛只粪便管理产生的氮氧化物（NO）排放的因素（即氮排泄率和每头动物的平均年氮排泄量）。本研究还使用这些因素和从文献中获得的其他值来计算反刍动物肠道发酵和粪便管理产生的牛 CH 排放量。它还提供了类似的粪便管理产生的 NO 排放以及牧场、草地和围场中沉积的尿液和粪便的排放。根据商业奶牛、商业肉牛、自给牛和育肥牛等不同牛种来计算这些排放。2019 年，南非的牲畜共产生了 3537 万吨二氧化碳当量（COe）的排放，其中包括牧场、草地和围场的排放。肠道发酵产生的甲烷占总排放量的 64.54%，其次是牧场、草地和围场（27.66%）。粪便管理对总排放量的 4.34%的 NO 排放负责，同时该源还产生 3.45%的 CH 排放。商业肉牛对总排放量的贡献率为 50.21%，其次是自给肉牛（36.72%）、商业奶牛（10.52%）和育肥牛（2.52%）。东开普省是牛只排放的最大产生者，有 866 万吨 COe，占四分之一。其次是夸祖鲁-纳塔尔省（714 万吨 COe，20%）和自由州省（565 万吨 COe，16%）。豪登省是排放量最低的产生者，仅占总量的 0.71 Mt COe（2%）。南非的排放因子高于非洲的数值，这表明开发国家因素的重要性，以避免排放的不确定性。由于国家的景观和环境条件，该国东部省份是该国牛只排放的主要来源。
