KINETICS OF PHOSPHATE RELEASE OF SLOW-RELEASE FERTILIZERS BASED ON BIOCHAR

Abstract

Slow-release fertilizers have been reported as a sustainable solution, which can replace highly soluble inorganic fertilizers. In our study, biochar based slow-release fertilizer was ssynthesized by cemented them in the MgO.MgCl₂ system. Mathematical models and leaching models were used to evaluate the efficiency of phosphorus release and their release mechanism. The extraction experiment showed that the treatments NT 4, NT 5 and NT 6 had 50 grams of biochar mixed with 25 grams of KH₂PO₄ and MgO respectively at the dosages of 3.0; 6.0; 15.0 g results in % P released after 24 h of 13.7; 8.3; 1.2% meets European standards for slow release fertilizer (required < 15%). The second-order kinetic models and the Higuchi diffusion model were suitable to explain the phosphorus release mechanism in the treatments. The results confirm that the slow release fertilizer in the study may have promising potential in sustainable agricultural application with many economic and environmental benefits.