Optimized tuning of rosin adduct with maleic anhydride for smart applications in controlled and targeted delivery of urea for higher plant's uptake and growth efficiency

Conventional urea is lost due to its high water solubility and microbial transformations which results low agriculture productivity and environmental pollution. To solve these problems, rosin adduct-coated controlled release urea fertilizer (RA-CRUF) was prepared. Properties of rosin adduct with maleic anhydride were optimized during synthesis by varying the reaction temperature (120, 140 and 160 °C), reaction time (2, 4, 6 h) and coating repeats (3, 6, 9 cycles). Twenty different rosin adduct compositions were coated by spraying of rosin adduct on urea to prepare RA-CRUF. The best optimized response of urea release for RA-CRUF was 510.00 mg L −1 in water at optimized values of coating repeats (6.79 cycles), reaction time (4.71 h) and reaction temperature (137.39 °C). The Fourier Transformed Infrared Spectroscopy confirmed the reaction of rosin with maleic anhydride at wavenumber 1780 cm −1 and 1856 cm −1 correspond to carbonyl of cyclic anhydride group. The optical microscopy analysis of surface and cross view of RA-CRUF showed a high homogeneity of coating surface. The cumulative urea release was 41.76% and 47.23% for RA-CRUF compared 100% and 82.6% for conventional urea in clay loam texture and loam texture soils respectively. RA-CRUF effect on growth performance of maize plant showed healthy growth and increase in chlorophyll contents up to 51.11 mg g −1 (clay loam texture soil) and 87.55 mg g −1 (loam texture soil).