Hydroxyapatite from fish scales: Synthesis, characterization, and preliminary potential as a lettuce fertilizer

Fertilization is crucial for agriculture, and phosphorus (P) is a key macronutrient for plant development. However, traditional phosphate minerals used in fertilizer production are becoming scarce, highlighting the need for sustainable alternatives. Thus, this study evaluated the effectiveness of hydroxyapatite (HAp) derived from Nile tilapia scales as a promising phosphorus source, comparing it to chemically precipitated HAp. Structural analyses confirmed that fish scale waste is a viable and sustainable material for HAp synthesis, offering controlled phosphorus release over time. Germination assays using lettuce ( Lactuca sativa ) seeds showed a high germination rate and enhanced root and shoot development in seedlings treated with HAp derived from fish scales, suggesting that HAp could be an effective alternative fertilizer without adversely affecting seed germination.