<p>The development of sustainable fertilizers seeks to balance productivity and environmental care. The objective of this study was to assess the sustainability of Zn complexed with glycine when used in the agricultural environment.&#xa0;For this purpose, the efficacy of the use of the Zn-glycine complex in improving Zn availability in the soil, its influence on nutrient uptake in the lettuce plant and the impact on greenhouse gas emissions, especially nitrous oxide (N₂O), were evaluated. The study was carried out on two soils of contrasting characteristics in the Mediterranean area. In addition, ZnSO₄, free glycine and unfertilised soil treatments were used to compare the effects.&#xa0;The Zn-glycine complex released Zn in a sustained manner, achieving similar yields to ZnSO₄ in acid soils and improving Zn uptake by 1.5 times in calcareous soils. Environmentally, the Zn-glycine treatment increased N₂O emissions relative to free glycine, ZnSO₄ and control by 60, 149 and 207% respectively, in calcareous soil. This was mainly because nitrification processes were more active than denitrification. Although in acid soil, N₂O emissions were not significant between the Zn and glycine treatments, an accumulation of NO₃^- in the soil by the glycine treatments was observed which could increase nitrate leaching pollution.&#xa0;These results highlight the need for soil-specific agronomic management strategies that optimize the efficiency of Zn-glycine fertilization while minimizing the associated environmental risks.</p> Graphical Abstract <p></p>