The demand for agricultural products is growing and is resulting in significant environmental impacts due to the overuse of fertilizers (and pesticides in some cases). There is a continued need to find sustainable methods in agricultural systems without harming the environment. Regenerative agriculture can be considered as one of the best methods of sustainable agriculture. The aim of this comparative life cycle assessment (LCA) study was to quantify the environmental impacts associated with the production of silage maize at different doses of fertilizers and pesticides under conventional agriculture and without the use of fertilizers and pesticides under regenerative agriculture. The input data were obtained from the experimental fields and supplemented by background process databases of Ecoinvent, World Food Live Cycle Assessment Database (WFLCD), and the French database AGRIBALYSE. The results of the study were related to six midpoint impact categories: global warming, marine eutrophication, freshwater eutrophication, freshwater ecotoxicity, marine ecotoxicity, and terrestrial ecotoxicity. Although the variant of growing silage maize without the use of fertilizers and pesticides according to the principle of regenerative agriculture showed the lowest burden on the environment, the yields of the cultivated silage maize were 43–55% lower than those of the fertilized variants.