Response of Soil-Fava System Irrigated with Urban Treated Wastewater to Nutrient-Enriched Biochar and Zeolite

With the global population rising, the demand for fertilisers to maintain soil fertility and boost crop productivity has surged. However, the excessive reliance on chemical fertilisers has raised serious concerns regarding economic and environmental sustainability. In response to this challenge, the utilisation of treated wastewater presents a promising opportunity for irrigation water and nutrient recovery. Among the tested materials, biochar and zeolite have emerged as highly effective in nutrient recovery from wastewater sources, particularly phosphate and ammonium, respectively. Indeed, when applied to the soil, these materials serve as soil amendments and function as slow-release fertilisers. This study aimed to investigate, through a plant-pot experiment, the utilisation of treated wastewater for irrigation purposes, coupled with the application of PO43− enriched biochar and NH4+ enriched zeolite, as slow-release fertilisers, and natural biochar and zeolite as control. The results revealed that wastewater, rich in soluble salts, increased soil electrical conductivity and adversely impacted plant growth. However, the application of biochar and zeolite effectively mitigated these adverse effects. Enriched biochar and zeolite acted as slow-release fertilisers, leading to increased biomass in fava plants and enhancing the uptake of nitrogen (N) and phosphorus (P).