<p>This study explores the beneficial agronomic use of marine gypsum, a residue of sea salt production, as an agricultural amendment. By repurposing this material otherwise discarded, we aim to reduce environmental impact and promote financial benefits for future generations. We evaluated marine gypsum’s use to enhance sandy soil fertility and its impact on nutrient absorption, melon production, and fruit quality in a semiarid region of Brazil.&#xa0;The experiment followed a completely randomized design with four replications and five treatments: (a) Control soil, (b) Marine gypsum (MG) at doses of 50%, 100%, and 200% of the recommended dose (RD) (9.2, 18.4, and 38.8&#xa0;g column⁻¹, respectively), (c) Agricultural gypsum (AG) at the 100% RD (27.3&#xa0;g column⁻¹). The experiment was conducted within a greenhouse, and each treatment consisted of two PVC columns with a soil capacity of 11 dm³. We evaluated the chemical and mineralogical properties of gypsum, soil chemical attributes, nutrient content in plant tissues, postharvest fruit quality, and melon fruit production.&#xa0;Marine gypsum, like agricultural gypsum, enhances the fertility of Arenosol (Quartzipsamment) and is recommended primarily as a source of calcium and sulfate for this soil type. Additionally, it improves melon plants’ absorption of Ca⁺² and SO₄ ⁻². Nevertheless, high doses should be used with caution, as they can reduce the Mg⁺² content during the crop’s initial growth period. A 50% RD of marine gypsum is sufficient to make melon production viable, but a 100% dose is recommended for optimal production and post-harvest fruit quality.</p> Graphical Abstract <p></p>