Overpopulation poses pressure on sustaining food production, demanding a significant increase in crop yield. However, a significant portion of nutrients in traditional fertilizers is lost during leaching and runoff causing economic loss and environmental threats. Here, we present a controlled fertilizer release strategy based on widely available and biodegradable chitosan. Hydrophilic chitosan polymer chains were crosslinked through freeze-thaw physical crystallization association to form polymer network hydrogels. Physical crosslinking ensures the excellent biodegradability of the chitosan hydrogels. Two-dimensional montmorillonite nanoclay flakes were mixed with the polymer to provide more crosslinking sites and form microporous structures after freezing for controlled fertilizer release. Over the course of around 20 days, up to 80% of loaded nutrient ions were released into the aqueous medium. In addition to the controlled release of fertilizers, the as-prepared hydrogels containing varying nanoclay content exhibited excellent water absorbency ranging from 25 to 140 g/g dry gel.

Biodegradable controlled release fertilizer based on chitosan-montmorillonite nanocomposites

ACS Fall 2021

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