A Green Control Release NPK Fertilizer Based on Micro/Nanoparticle of Chitosan Impregnated Activated Coir Fiber

Abstract

Background: Conventional chemical fertilizers enhance agricultural output but deteriorate soil quality and fertility while causation of health and environmental issues. Therefore, continual use of chemical fertilizers is not sustainable. Control release nanofertilizer is one of the solutions to said issues. Nanofertilizers use metallic nanoparticles and toxic cross-linkers (eg. Glutaraldehyde, Glyoxal and Methacrylic Acid) which also pose risks to health and environment. Synthetic, non-biodegradable costly raw material based nanofertilizers will also create new-generation-waste in future which is not sustainable. Objective: Development of an environment friendly nanofertilizer for prolong control release of plant macronutrients - Nitrogen, Phosphorous and Potassium (NPK). Methods: Chitosan was obtained from deacetylation of chitin which was extracted from shrimp exoskeleton. Micro/nanoparticles of chitosan were synthesized with ionotropic gelation method excluding toxic cross-linkers. Macronutrient loaded nanoparticles were impregnated to micro and nano pores in activated coir fiber followed by coating with a natural exudate water diffusional barrier. Macronutrient release behaviour and efficacy of control release fertilizer were studied against conventional bulk fertilizer. Results: Mean size of nanoparticles was 100 nm. FTIR analysis showed the macronutrient interaction with micro/nanoparticles of chitosan. Macronutrients were incorporated into nanoparticles at 12 % loading efficiency and 20 % entrapment efficiency. The developed fertilizer showed control release of macronutrients even beyond 90 days whereas commercial fertilizer showed an initial burst lasting a negligible release after 30 days. Results from pot trials indicated that nanofertilizer enhances yield performance of rice plants against commercial fertilizer. Conclusion: A green nanofertilizer can be developed with a simple method using biocompatible, biodegradable, non-toxic and renewable natural based raw materials for prolong control release of plant macronutrients excluding toxic chemicals. Since the starting materials are coir fiber and shrimp exoskeleton which is a waste, it could significantly reduce the production cost hence present study discloses an economically sound, environment friendly and socially responsible nanofertilizer.