Biochar-Based Controlled Release Nitrogen Fertilizer Coated with Polylactic Acid

Conventional nitrogen (N) fertilizers tend to dissolve in the water quickly without allowing sufficient time for the plants to uptake the N nutrient. The consequence is low N use efficiency (NUE) (NUE < 50%) due to losses by volatilization of N in air, runoff, and leaching in the field that is rising severe environmental pollution. Controlled-release fertilizers (CRFs) uses for the controlled release of N nutrients as an innovative solution. Research conducted using different compositions and coating methods for CRFs yet underdeveloped provides inadequate release control from fertilizer particles. The complexity of the preparation methods, biodegradability, and other physical properties are questionable in the modern agriculture sustainability achievement. This study aims to develop a novel biochar-based controlled-release N fertilizer (BCRNF) by explicitly formulating the nitrogen fertilizer particles, using polylactic acid (PLA) as coating material applied via the spray coating method. The new BCRNF was synthesized by pelletizing the mixture of Biochar and Ammonium Sulphate (AS) into particles, followed by coating 5 wt% PLA solution with different coating contents at 8.25%, 14.10%, 15.89%, 17.72%, and 21.15% respectively. The results indicated that the release time of 70% N from the BCRNFs particles into the water could be controlled from 2 to 27 days when PLA coating content increased from 8.25% to 21.15%. The surface morphology and physical properties of the BCRNF particles were also significantly changed when the coating contents changed. The study demonstrated that the N release of the BCRNF is controllable and predictable when appropriately designing BCRNF formulations and properly coating the BCRNF particles with PLA.

Automated summary

This study aims to develop a novel biochar-based controlled-release N fertilizer by formulating nitrogen fertilizer particles and applying a polylactic acid coating via the spray coating method. The results showed that the release time of 70% N from the BCRNFs particles into water could be controlled by adjusting the PLA coating content.