Enhancing N Use Efficiency and Reducing N₂O Emission by Coating Urea with Newly Identified Bio-Molecule (C₂₀H₃₀O₂), Nano-Zn Oxide and Nano-rock Phosphate

The increasing use of nitrogenous fertilizer and its importance in Indian agriculture has attracted the attention of environmentalists. There is a greater concern that nearly 30–60% of applied N is lost in the form of ammonia from the agricultural soils through volatilization. To reduce such loss, urea can be coated with pine oleoresin, a novel coating material, for making slow release urea with minimal cost using the solvents like petrol. The POR-coated urea releases N slowly by the action of a physical barrier and increase N availability by inhibiting urease activity through antibacterial properties and reduces volatilization loss by acidifying alkaline micro-sites in soil. It also improves the biomass yield, nitrogen uptake and nitrogen use efficiency. Keeping in view of the above, the current investigation was aimed to coat urea with nano-ZnO (<100 nm) and nano-rock phosphate (<48.6 nm) using pine oleoresin (POR) as a coating agent and to study their effect on nitrous oxide (N₂O) emission. Significant improvement in N use efficiency ranging 10–20% was observed in greenhouse studies. Further, the results clearly demonstrated that further encapsulation of POR coated urea with nano-Zn oxide (<50 nm) and nano-rock phosphate (<100 nm) reduced nitrous oxide emission by 30–40%. Nano-ZnO coated urea showed the least N₂O emission (0.28 μg N₂O mg⁻¹ N) followed by 35% nano-RP coated urea (0.30 μg N₂O mg⁻¹ N). The results thus indicated that coating urea with 2% nano-ZnO and 35% nano-rock phosphate could be used as a potential means to reduce N₂O emission from fertilizer N.