## 3 Results and Discussion  
### Cassava Cultivation  
Impacts from cassava cultivation are expressed per kg of harvested cassava root and a distinction is made between the following contribution groups: (i) direct field emissions, (ii) mineral fertilizer production, (iii) field work processes, (iv) pesticide production, (v) transport, and (vi) the burning of cassava leaves. Direct field emission means environmental impact from those emissions that are caused by the application of fertilizers and pesticides in the field. Mineral fertilizer production and pesticide production describe the environmental impact of providing the respective inputs of mineral fertilizers and pesticides. Transport includes both the provision and the operation of the means of transport. Burning means the environmental impacts from the combustion of cassava leaves on the field.  
Environmental impacts of traditional cassava cultivation are dominated by the production of mineral fertilizers (75-98%) for input-related LCIA categories (CED, DEF, WSI) and by direct field emissions (40-100%) for output-related LCIA categories (GWP, OFP, AP, HTP, ETP) (Figure 2). Mineral fertilizer production is governing CED because of the high energy demand of chemotechnical nitrogen and phosphate recovery. Emissions contributing to the GWP of traditional cassava cultivation are mainly N2O and CO2 from fertilization with 60% and 37%, respectively. The burning of the leaves causes environmental impacts mainly in the two impact categories OFP and AP, with contributions of 39% and 6%, respectively. Most relevant emissions in this context are N2O and SO2, which are causing 98% and 2% of the total OFP impacts, respectively.  
For modern cassava cultivation, Figure 2 shows that the direct field emissions dominate most output-related LCIA categories (GWP, AP, HTP and ETP) system with 39%, 84%, 86% and 100%, respectively. A high share of direct emissions in total environmental impacts is also reported by [PERSON] et al. for potato production [36]. Emissions contributing to the GWP of cassava are mainly CO2 and N2O with 60% and 36%, respectively. Direct field emissions from nitrogen fertilization are the source of N2O, while exhaust gases from tractors and harvesting machines used in the modern cultivation system are causing more direct CO2 emissions in comparison to traditional production. The burning of leaves contributes with 11% and 2% to OFP and AP, respectively. Input-related LCIA categories (CED, DEF) are mainly dominated by field-work processes (40%, 46%) and transport (35%, 44%), while, for WSI, the production of mineral fertilizers (64%) is the biggest contributor. The great influence of mineral fertilizer production on the WSI is initially surprising. In a more in-depth analysis, it was found that impacts for WSI from mineral fertilizer production are mainly caused by up-streamprocesses for phosphate recovery, namely phosphoric acid and sulfuric acid. Even more surprising is the high influence of transport processes on DEF. Again, an up-stream process is responsible for this; onshore wells that produce the fuels used in the transport processes cause 95% of these impacts.  
In addition to the difference in mechanization, different yields in both systems lead to differences in the results.