Effect of Polyethylene Glycol and Humic Acid Coating on NPK Release From Controlled-Release Fertilizer.

Plants require essential macronutrients such as nitrogen (N), phosphorus (P), and potassium (K), but their availability in soil is often inefficient due to evaporation, leaching, and binding. Controlled-release fertilizers (CRFs) provide a solution by regulating nutrient release over time. This study evaluates the effects of two coating materials, polyethylene glycol (PEG) and humic acid, on the release patterns of N, P, and K during an 18-week incubation using Inceptisol from Bogor, Indonesia.