Sulphate-supplemented NPK nanofertilizer and its effect on maize growth

Sulphate-supplemented nitrogen, phosphorus and potassium (NPKS) fertilizer was nanoformulated through ionic gelation of chitosan (CS) and tripolyphosphate (TPP) at pH value of 5.5 to afford a series of nanofertilizers. The CS-TPP nanoparticles and CS-TPP-NPKS nanofertilizers were engineered using different dose of CS (0.125, 0.25, 0.5 and 1%) and NPKS fertilizer (20, 40 and 60 ppm). These nanoparticles were characterized through particle size distribution, zeta potential, SEM, XRD, FTIR, EDX and ICP-MS. The results revealed CS-TPP-NPKS particles with size range of 220-530 nm, polydispersity index (PDI) value between 0.2-0.5 and positive zeta potential. A preliminary evaluation of these nanoparticles along with inorganic NPK and NPKS fertilizers were conducted under greenhouse condition using maize (Zea maysL.) as a test crop. Findings from this study showed that inorganic NPKS (20:7:3:0.5) fertilizer, CS-TPP nanoparticles, and formulated NPKS nanofertilizers gave higher maize plants growth increases than NPK fertilizer and control treatments. The tallest plant (37.73 cm) and highest number of leaves (9) were recorded with the CS-TPP-NPKS nanofertilizer treatment obtained using 1% CS/NPKS (40 ppm). On the other hand, application of the nanoformulated derivative with 0.25% CS/NPKS (20 ppm) produced maize plants with superior chlorophyll content with 12.71 chlorophyll index value. A highly varied magnitude of the coefficient of variation in nutrient contents and uptake was recorded among the treatments. These results revealed that the incorporation of sulphur nutrient into NPK fertilizer and its transformation to nanoparticles have the potential characteristics for effective and productive growth of maize and sustainable agricultural activities.