Effects of fertilizer produced from agro-industrial wastes on the quality of two different soils

A newly developed sustainable fertilizer, known as SB, was created by blending organic and mineral components using agro-industrial waste, sulphur, and orange residue, bound together with bentonite. It was extensively tested on two distinct soils with different chemical and biological properties, comparing its effectiveness to traditional chemical (NPK) and organic (horse manure, HM) fertilizers, with unfertilized soil as a control (CTR). The introduction of SB did not alter soil texture but significantly impacted soil chemistry and biology. It positively influenced the labile fraction of soil organic matter, resulting in a 15% increase in soil microbial biomass, total phenolic content, cations, bacterial colonies, and enzyme activities, with varying effects depending on soil characteristics. SB demonstrated a beneficial effect on both soil types, with optimal concentrations determined to be 2.8 for Motta and 4.2 for Lazzaro, highlighting the importance of soil characteristics in fertilizer effectiveness. In conclusion, SB represents a promising innovation for transitioning from traditional agriculture to a more sustainable and circular approach, offering economic and environmental benefits by reducing waste disposal costs and decreasing reliance on mineral fertilizers in line with circular economy principles. This study emphasizes the need to consider soil properties when optimizing fertilizer use.