NITROGUARD, AN INNOVATIVE BIOFERTILIZER PAINT FOR TREE TRUNKS USING AZOTOBACTER CHROOCOCCUM (NITROGEN FIXING BACTERIA)

Excessive use of chemical nitrogen fertilizers has caused serious environmental and soil health problems, especially in long-term tree cropping systems. To provide a sustainable alternative, this study developed NitroGuard, an innovative biofertilizer paint formulated with the free-living nitrogen-fixing bacterium Azotobacter chroococcum for application on tree trunks. The water-based formulation, prepared using slaked lime, casein, and glycerol, maintained viable bacterial cells (≈10⁸ CFU/mL) for 48–72 hours after application. The bacteria colonized bark microcrevices and gradually migrated to the rhizosphere, contributing to biological nitrogen fixation and the release of plant growth–promoting substances. Field trials on mango, guava, and neem trees showed improved leaf greenness, shoot growth, and overall vigor compared to untreated controls. NitroGuard offers a low-cost, eco-friendly alternative to chemical fertilizers for tree crops.