Abstract

Water hyacinth (WH) is among the most invasive aquatic weeds worldwide, posing severe ecological and socioeconomic challenges. Despite these impacts, WH also presents an opportunity as an organic resource for soil amendment in sustainable agriculture. However, scientific evidence on the nutrient potential and safety of WH-based compost remains limited. Therefore, this study aims to evaluate the nutrient content and heavy metal safety of compost made from WH and cattle manure to reduce dependency on chemical fertilizers and promote nutrient recycling. The composting was process lasted 60 days, during which three distinct WH-to-manure ratios (6:6:2, 8:4:2, 10:2:2) were used. Physicochemical properties, including pH, moisture content, electrical conductivity (EC), total nitrogen, available phosphorus (P), organic carbon (OC), and exchangeable bases, were analyzed, along with concentrations of heavy metals such as Zn, Cd, Pb, Cu, Fe, and Mn. The compost pH ranged from 8.66 to 8.96, EC values remained below the acceptable 4 dS/m limit, and OC and nitrogen content varied among samples, with sample B showing the highest levels. All heavy metal concentrations were within FAO/WHO permissible limits. However, TN and available P values were below optimal ranges. The results indicate that WH-based compost is safe and has potential as a sustainable soil amendment, although nutrient enhancement strategies are recommended. According to the study, combining water hyacinth compost with cattle manure is a sustainable and efficient way to replace chemical fertilizers. However, for more successful agricultural applications, its nutrient content needs to be improved.