Utilization of Agricultural Waste in Biofertilizer Production: A Sustainable Procedure for Supporting Zero-Waste Approach

The increasing pressure on global agricultural systems to adopt sustainable and circular practices has propelled the exploration of organic waste valorization pathways. Among these, the conversion of agricultural waste—often abundant and underutilized—into biofertilizers represents a promising avenue for both environmental protection and agronomic enhancement.

Agricultural waste, primarily composed of discarded leafy greens, fruit peels, stems, and overripe or damaged produce, is rich in organic matter and bioactive compounds. However, its management remains a challenge in many agricultural regions, particularly due to seasonal accumulation and lack of structured recycling strategies. Instead of being landfilled or incinerated, these waste streams can serve as ideal substrates for microbial fermentation and composting technologies that produce nutrient-rich biofertilizers.

This study highlights the physico-chemical characteristics of common agricultural residues such as tomato vines, pepper stalks, cucumber peels, and salad waste, and evaluates their compatibility with selected microbial strains—Azotobacter spp., Bacillus subtilis, Trichoderma harzianum, and phosphate-solubilizing bacteria. Through solid-state fermentation and controlled composting trials, the nutrient release profile, microbial viability, and phytotoxicity index of the resulting biofertilizers were assessed.

The results demonstrated that agricultural waste, when pre-treated to optimize carbon-to-nitrogen ratios and moisture content, supports robust microbial growth and enzymatic activity. Moreover, the application of these biofertilizers in test plots of lettuce and spinach yielded significant improvements in plant vigor, chlorophyll content, and root architecture compared to conventional compost or untreated controls.

Importantly, the integration of such biofertilizer production systems into local food supply chains contributes to a circular bioeconomy—reducing reliance on synthetic agrochemicals, minimizing greenhouse gas emissions from organic waste, and promoting zero-waste agricultural ecosystems. This research underlines the potential of agricultural by-products as an untapped resource in the green transition of agriculture and opens the door for localized, low-cost, and high-impact sustainable practices.