Agronomic Potential of Compost from Unconventional Organic Waste Sources and the Effect of Trichoderma harzianum T-22 on Durum Wheat’s Early Development

Composting organic waste enhances soil fertility, supports plant growth, and offers a sustainable waste management strategy. This study evaluated the agronomic potential of three compost types derived from unconventional sources: (i) sewage sludge, (ii) slaughterhouse animal by-products (ABPs), and (iii) cheese industry waste. The impact of Trichoderma harzianum strain T-22 inoculation was also assessed in relation to the early development of durum wheat (Triticum turgidum subsp. durum) under greenhouse conditions. Compost type significantly influenced plant emergence and growth, with sewage sludge-based compost showing the best performance. T. harzianum T-22 inoculation produced mixed results; it improved growth in specific combinations (CS-1/3 and CA-1/4) but inhibited it in others (particularly CW-based composts). These findings underscore the importance of compost source selection and highlight that microbial inoculation effects are substrate-dependent. This work supports sustainable composting practices and fungal waste valorization to optimize plant growth in sustainable agriculture.