Chitosan gels in the nutrient controlled release: a review

The use of slow and controlled release fertilizers (S/CRFs) has been beneficial in enhancing fertilizer utilization and crop yields, improving food security. However, the massive use of conventional S/CRFs has also polluted soil, water, and air, which poses a challenge to the sustainability of modern agriculture. To address this, a more efficient and environmentally-friendly material for crop nutrition is needed. Chitosan gels have proven to be an ideal carrier for nutrient transport given their biodegradability and high adsorption characteristics. This paper reviews the cross-linking of chitosan gels, preparation methods, nutrient transport, and performance, and how they contribute to sustainable agriculture. In addition, we detail the contribution of chitosan gels fertilizers to greenhouse gas reduction, soil conditioning, and crop yield improvement. In conclusion, although further research is needed on chitosan gels fertilizers as S/CRFs, it is expected that their use could lead to improved nutrient efficiency and reduced environmental pollution from a long-term development perspective.