Interaction of Aspergillus niger in Double-Coated Urea Granules Reduces Greenhouse Gas Emissions from N Fertilization

Urea is the main nitrogen source applied in agriculture and directly impacts agricultural productivity. However, it presents significant losses that reduce plants’ nitrogen use efficiency (NUE) and promote greenhouse gas emissions, such as N 2 O. The coating technology allows for an increase in the NUE, making the nutrient available gradually and uniformly, and combining with microorganisms’ action. This work developed and evaluated a double-coating system based on castor oil–polyurethane and maize starch activated by Aspergillus niger for urea granules. We tested the coated urea granules in Palisade grass ( Brachiaria brizantha ) and measured losses of N 2 O and NH 3 . The results showed that the combination between controlled release and Aspergillus niger action reduced the N 2 O and NH 3 emissions, suggesting a local buffering pH effect. The urea loss reduction significantly impacted plant development, increasing N use efficiency, dry mass production, and N uptake. The results support the suitability of a coating system combining controlled release and microorganisms, aiming to better synchronize the nutrient with the plant and reduce environmental impacts. Graphical Abstract