Urease Inhibitor and gibberellic acid reduce nitrogen losses and improve maize performance in a semi-arid soil

Abstract Low nitrogen (N) use efficiency and substantial gaseous N losses constrain the effectiveness of N fertilization in low-organic-matter soils, particularly under semi-arid conditions. A field experiment was conducted during summer 2021 at the research farm of The University of Agriculture Peshawar, Pakistan, to determine whether a urease inhibitor (UI) and gibberellic acid (GA₃), applied individually or in combination, could reduce gaseous N losses and improve N recovery and maize performance. The experiment was arranged in a randomized complete block design with five treatments and four replications: control, urea (200 kg N ha⁻ 1 ), urea + GA₃ (60 g ha⁻ 1 ), urea + UI, and urea + UI + GA₃. The application of UI-coated urea significantly reduced total NH₃ losses by 74% and N₂O emissions by 57% compared with urea alone. Compared with sole urea application, UI-treated urea substantially reduced cumulative NH₃ loss and N₂O emissions while increasing 15 N recovery, grain yield, and total N uptake. The combined urea + UI + GA₃ treatment produced the greatest agronomic response, increasing 15 N recovery by 50%, grain yield by 32%, and total N uptake by 35% relative to sole urea. These results indicate that UI primarily reduced gaseous N losses, whereas the addition of GA₃ further improved crop physiological performance and N utilization. GA₃ also improved chlorophyll content, gas exchange characteristics, antioxidant defense, and membrane stability, indicating enhanced physiological performance and stress tolerance. These findings demonstrate that integrating UI with GA₃ can simultaneously improve fertilizer-N retention and crop performance under semi-arid, low-organic-matter soil conditions. This approach may provide a practical strategy for improving N-use efficiency while reducing the environmental footprint of maize production.