(446c) Biowaste-Derived, Nanocomposite-Based Slow-Release Fertilizer Encapsulated with a Super Thin Coating Layer

Nutrient management is an important issue in fertilizer study to enhance crop yield with minimal environmental impact. Achieving the right balance between the amount of fertilizer applied for the nutrient absorption and minimizing harmful effects like soil degradation due to nitrite accumulation is crucial. Slow-release fertilizers (SRFs) have received significant attention as they offer a promising solution for crop nutrient management by improving nutrient efficiency, fostering crop growth, and reducing fertilizer waste and pollution through optimization and control of the extended release period.

However, current SRFs suffer from challenges in high release speed and high cost. To tackle these challenges, this study proposes a novel fabrication method to prepare bio-based SRFs with a controllable fertilizer release function and super thin coating layer to reduce production costs. A nanoclay-based bio-polyurethane membrane is synthesized from modified bentonite clay and bio-polyol derived from biomass residue. The modification of bentonite clay results in a fully exfoliated nano clay distributed in the polymer matrix of the membrane, followed by the addition of polyol that enables in-situ reaction and formation of a denser cross-linked structure. Ultimately, the synthesized nanoclay-based slow-release fertilizers (CSRFs) demonstrated excellent control over nitrogen release for a time period of more than one month and promoted plant growth of soybean in a hydroponic system. The soybean showed improved plant height, leaf greenness, shoot biomass, and yield compared to traditional fertilizers.

Additionally, this work provides a detailed examination of the synthesis of modified nanoclay, the encapsulation of urea fertilizer by bio-nanocomposite, and the study of the dynamic nutrient release profile. The sustainable CSRFs fertilizers from bio-waste provide a cost-effective solution for optimizing the nutrient release profile, demonstrating the potential to substitute conventional fertilizers.