Modeling environmental and nutritional impacts of vegan agriculture
Creators: name: Krayer, Patricia
Publisher: name: ZHAW Zürcher Hochschule für Angewandte Wissenschaften
Year: 2021
Subjects: Food system modeling
Vegan agriculture
Food system analysis
577: Ökologie
630: Landwirtschaft

description: A transformation of the food system is needed to stay within the planetary boundaries and to feed the world, at the same time. One promising approach to reduce food system-related environmental impacts is the reduction of livestock, since animal-based products are consistently associated with higher environmental impacts than plant-based products. However, in today’s agriculture, plant- and animal-production systems are heavily interlinked and systemic consequences of strong livestock reductions, therefore, not clear. The interlinking especially holds true for organic agriculture, where manure is a valuable nutrient source. The goal of this thesis was therefore to analyze effects on nutrition and environment of a shift to a 100% vegan world for different production systems in the year 2050. For the analysis, a modeling approach was chosen: SOLm, a mass and nutrient flow model, was adapted to enable different choices of crop rotation patterns, treatment systems for grasslands and to choose the vegan and organic shares of the food system. Six vegan scenarios with different model assumptions were implemented to explore potential outcomes of a vegan world. Three of these scenarios described a vegan-conventional world, the other three a vegan-organic world. The scenarios differed further in their total cropland area and the applied crop rotation patterns, which were based either on existing crop distributions, literature, or on results of linear optimization problems. The optimization problems were designed to minimize the necessary cropping area under the constraints of fulfilling nutritional requirements (in a veganconventional world) or nutritional and, additionally, agronomic requirements (in a vegan-organic world). For the analysis of environmental impacts, a selection of already implemented indicators was made. To assess the nutritional impacts of the food systems, data about macro- and micronutrient contents from the USDA SR28 database was collected, cleansed and integrated into SOLm. Furthermore, as indicator for food quality, the aggregate index AHEI-2010 was calculated for each scenario. Considering the same cropland area as in the reference scenario, the model resulted in insufficient amounts of calories, proteins and fat for all of the vegan-organic scenarios. Although a crop rotation design based on actual stockless systems led to a better performance than other crop rotations, fat supply was still found to be critical and far below the threshold. In contrast, both vegan-conventional scenarios with the same cropland achieved sufficient amounts of calories, proteins and fat. However, the supply of vitamin B12 and D was still far below the requirements. Further, calcium and selenium were found to be critical in those scenarios. Most vegan scenarios showed a better environmental performance than the reference scenarios, however, one vegan-conventional scenario resulted in a high increase in irrigation water use. The results indicate that the compatibility of vegan and organic agriculture is limited. To provide sufficient calories, proteins and fat to feed the world, the utmost share of organic agriculture was found to be 50% with a vegan share of maximum 40%. The results suggest that a transition might help to respect planetary boundaries and provide sufficient macro- and micronutrients, at the same time. However, it was found to be nearly incompatible with organic agriculture due to the higher share of non-productive grassland areas and lower yields in such production systems.