Formulation of Polymer Nano-Composite NPK Fertilizer [Cellulose-Graft-Poly (Acrylamide)/Nano-Hydroxyapatite/Soluble Fertilizer] and Evaluation of Its Nutrient Release

Polymer nano-composite fertilizer formulation has the potential to enhance nutrient use efficiency. A slow-release fertilizer (SRF) was formulated by incorporating nano-hydroxyapatite (nano-HA), urea, (NH4)2HPO4 and K2SO4 into the cellulose-grafted copolymer, and the release of nutrients was assessed using laboratory incubation experiment. Significantly higher (p ≤0.05) mineral nitrogen (NO3-N + NH4-N) content was observed in conventional fertilizer (CF) treatment in the first 4 weeks compared to SRF treatments and the control. Mineral N content in SRF treatments increased considerably between the 8th and 12th week and declined in the 16th week. Significantly higher P content was observed in CF treatment relative to SRF treatments in the 4th week, whereas in the 8th week, some SRFs released significantly higher than CF. The data revealed reduced chances of leaching losses with concomitant pollution to the groundwater and toxic effect on the plant roots, as well as synchronized nutrient release to cater to the requirement of crops.