Green synthesis and evaluation of calcium-based nanocomposites fertilizers: A way forward to sustainable agricultural

Only 47% nitrogen of fertilizer is taken up by a plant whereas more than 40% nitrogen of total applied fertilizer is lost to environment that causes several environmental as well as economic consequences. Slow-release fertilizers are considered as a possible large-scale solution for nitrogen loss. The present study aims to stabilize urea by coating with four different materials including calcium phosphate (CP), gypsum powder (GP), calcium nitrate (CN), and gelatin (G) individually and in combination for slow release of nitrogen to sorghum crop. The physical and chemical characteristics of coated urea were examined by FT-IR, powder XRD, SEM, and rushing strength. Results showed that coating of CP, GP, and CN over urea was uneven and rough while G coating was smooth and admirable, and no pore was observed on the surface and indicated a weak water-urea interaction. Similarly, CPG coating over urea showed a maximum crushing strength of 2.38 N/m2. Slow-release and soil leaching analysis revealed that G coated urea showed the maximum 39.12 and 779.36 ppm nutrient loss after 15- and 480-min treatment, respectively which is much better than uncoated urea (99.81 and 993.65 ppm). Results reported that the maximum plant height, diameter, and chlorophyll were observed as 132.91 ± 1.52 cm, 24.56 ± 1.00 mm, and 56.30 ± 1.03 mg/m2 with CNG coated urea. Similarly, CNG also revealed the maximum dry matter yield (DMY) of 25226.15 kg/ha in shoots and 2633.50 kg/ha in roots, nitrogen uptake (NU) of 18153.75 kg/ha in shoots and 233.99 kg/ha in roots, and apparent nitrogen recovery (ANR) of 71.14% in shoots and 4.55% in roots. It is concluded that CNG coated urea showed better DMY, NU, ANR, and pot analysis, and it is recommended as a slow-release fertilizer for large scale application to minimize nutrient loss and maximize crop production.