## 3 Results and Discussion
### Comparison with Previous LCA Studies on Maize Production  
The results of this study were compared to previously published LCA studies on maize production. [PERSON] [41] analyzed the double high production system for summer maize production and found that N fertilizer applications were reduced by 2.37%, and applications of P were reduced by 56.54%. According to the authors, reduced fertilizer uses during the winter wheat-summer maize production system significantly reduced acidification, greenhouse gas emissions, and aquatic eutrophication. The range of GWP values from the studies was 346.9 kg of CO2 eq. per ton of maize production, with fertilizer application accounting for 83%. The contribution to GWP by seed sowing, tillage, harvesting, transport, and pesticide stages was negligible.  
The environmental impacts of the entire maize crop production process and the identification of hotspots in the production chain were studied by [PERSON] [42]. The results of acidification (93%), global warming (54%), marine eutrophication (99%), and terrestrial eutrophication (97%) were associated primarily with the fertilization process that contributes significantly to freshwater eutrophication. Human toxicity effects (cancer 59% and non-cancer effects 52%) and aquatic freshwater ecotoxicity (65%) values were associated primarily with the production, transport, and packaging of superphosphate. The results of [41] are higher than those observed in this study due to the inclusion of some additional  
Figure 6: Normalization of substance impacts on human health, ecosystems, and resources using the two endpoint methods (ReCiPe and IMPACT 2002+).  
factors in the system boundaries. Those factors, including buildings, machinery, and humus mineralization, are typically excluded from the analysis. Moreover, in [41], the impact categories are dominated by field emissions, followed by tractor use, pesticide production, and fertilizer production. Given the availability of numerous impact assessment methods, a detailed comparison of the additional impact categories may not be possible.  
[PERSON] [43] assessed the environmental impacts of GWP using the LIME-2 and ReCiPe methods. The highest contribution to the global warming impact category occurred in the farming process in which fertilizer was used. The GHG emissions estimated in the ReCiPe method were slightly higher than those in the LIME-2 method (approximately 20-30%).  
[PERSON] [44] investigated the environmental impacts of maize production and estimated the amounts to be 14.9 kg SO\({}_{2}\) eq for acidification and 0.634 kg C\({}_{2}\)H\({}_{4}\) eq for photochemical oxidation. Therefore, producing this crop according to this type of production system means that the rate of inputs consumed and the identified negative impact on the environment during planting are essential for properly managing resources.  
[PERSON] [7] assessed the environmental impact of producing four maize genotypes using three rates of N fertilizer application based on the LCA method. The study noted that the production of one ton of grain from the urea-treated hybrid KSC 647 emitted the lowest levels of NH\({}_{3}\) (2.158 kg/ton, N\({}_{2}\)O (0.368 kg/ton), NO\({}_{\chi}\) (0.449 kg/ton), CO\({}_{2}\) (64.510 kg/ton), CH\({}_{4}\) (0.090 kg/ton), and SO\({}_{2}\) (0.115 kg/ton) of the four genotypes. Potential environmental damage was reduced by selecting a high-yielding genotype that reduced the rate of emissions per functional unit of maize grain yield.