Wim de Vries1,2, Jia Wei1, Hans Kros1, David Windhorst3 and Lutz Breuer3
1Alterra, Wageningen University and Research Centre (WUR), PO Box 47, 6700 AA Wageningen, The Netherlands
2Environmental Systems Analysis Group, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands
3Justus-Liebig University of Giessen, Heinrich-Buff-Ring 26, 35392 Gießen, Germany
Abstract
A simple fast calculation approach has been developed that gives insight in the overall effects of dietary changes on nitrogen (N) emission to air and water by 2050 for ten identified world regions. The impact of dietary change on N fertilizer and N manure applications and related emissions was based on the consumption of crop and animal commodities, making use of the FAO data from 1961 to 2005 and extrapolating the data towards 2050 in response to five dietary change scenarios. Scenarios included a ‘North American Diet’ (NAD), a ‘Same Diet’ (SD), a ‘Business-as-Usual’ (BAU) diet; a ‘Demitarian Diet’ (DD) and a ‘Vegan Diet’ (VD). The calculated N2O and NH3 emissions and N leaching/runoff for the reference year (i.e. 2005) showed good agreement with various literature estimates. N2O was the most persistent problem, even increasing under the VD scenario, due to the increased use of N fertilizer to cultivate food crops and the assumed high contribution of N fertilizer to N2O emission. NH3 emissions increased three times in the NAD scenario, while it decreased by 13% in the VD scenario. This happens because NH3 emissions mainly follow the N manure trends. In the VD scenario, N leaching/runoff remains equal to 2005, while it increases by 145% in the NAD scenario. Overall, results show that dietary change affects most strongly NH3 emissions, followed by N leaching/runoff and then N2O emissions. Only a severe reduction in meat consumption can substantially reduce N losses with the exception of N2O emissions.