Assessment of cleantech options to mitigate the environmental impact of South African dairy and maize farming

Oral presentation
Introduction: Agriculture accounts for about 10 % of national greenhouse gas emissions in South Africa in 2010. Food value chains, both primary production and downstream processing, have been identified as one of the priority areas to reduce environmental impacts of food production. The implementation of clean technologies, which are customised to South African food value chains and help to mitigate these impacts, are therefore crucial. Goal and Scope: In order to make science-based decisions about the implementation of clean technologies, the project “Applying Life Cycle Assessment for the mitigation of environmental impacts of South African agri-food products” aimed at quantifying environmental mitigation potentials when applying clean technologies. The environmental impact of technologies currently applied at South African dairy and arable farms was analysed for environmental hotspots. Based on this data, the effect of applying the following mitigation options were analysed: (1) Milk production: Adding the methane inhibitor 3-nitrooxypropanol (3NOP) to the feed of lactating Holstein cows. (2) Maize production I: The use of variable frequency drive in centre-pivot irrigation of maize. (3) Maize production II: Provision of electricity for pumping irrigation water directly by solar panels. The following nine environmental impact categories were analysed: global warming potential (GWP), cumulative energy demand (non-renewable: fossil and nuclear), eutrophication (freshwater and marine), human toxicity (cancer and non-cancer effects), freshwater ecotoxicity and land use. Results: Firstly, adding 3NOP to the feed of cows decreases the GWP of milk at farm by 18 %, without changing the impact in other categories. Secondly, integrating a variable frequency drive for the irrigation of maize decreases the impact of maize in six of the considered impact categories by 11 % to 18 %, while in three categories, there is no substantial change. Finally, powering maize irrigation w