Abstract
The growing global food demand increased the use of chemical fertilizers, causing environmental issues. This study explores fertilizers from agro-industrial waste materials on the basis of different percentage of food wastes, focusing on their environmental and soil impact, particularly on global warming potential (GWP). The fertilizers investigated include vermicompost (VC, 70% wood sawdust + 30% food wastes); compost 1 (C1, 50% wood sawdust + 50% food wastes); compost 2 (C2, 10% straw + 90% food wastes); sulfur bentonite (SBC, 90% SB + 10% food wastes). Six months post-fertilization, the soil's chemical and biological properties, revealed significant improvements in respect to unfertilized soil (control). A Life Cycle Assessment (LCA) methodology was used to comprehensively evaluate the entire life cycle of these fertilizers, from production and application to their environmental effects. Our findings highlighted the different environmental impact of these fertilizers. Vermicompost demonstrated lower CO2 equivalent emissions during the vermicomposting process, emphasizing its environmental sustainability. It also showed positive effects on soil chemical and biological properties, enhancing soil health and fertility. Despite SBC positively affected soil properties, it was identified as the fertilizer with the greatest environmental impact. Consequently, from a benefit-cost perspective, the ranking of the fertilizers was VC > C2 > C1 > SBC. These findings underscore that it is possible and necessary transitioning towards sustainable fertilizers derived from waste materials to mitigate the environmental degradation associated with the production and use of conventional fertilizers. By adopting circular economy principles and promoting the use of organic fertilizers, the agricultural sector can enhance productivity while adhering to environmental sustainability standards.