Background <p>This pioneering research aims to assess Djdi Ocher (Khuzam Shale), a naturally occurring Pharaonic fertilizer from Southern Egypt, as a unique sustainable soil amendment. The study focuses on blending Djdi with sandy clay soil (CS) in various ratios to evaluate its effects on the growth and development of Eruca vesicaria.</p> Results <p>In a pot experiment, <i>E. vesicaria</i> seeds were germinated in three different Djdi-to-soil ratios: (1:1; Djdi: CS1), (1:2; Djdi: CS2), and (1:3; Djdi: CS3). After 15 days, seedlings were harvested for comprehensive analysis. XRD analysis characterized Djdi as a sandy loam enriched with minor and major oxides, particularly iron oxides. Soil analysis revealed that Djdi: CS2 and Djdi: CS3 treatments recorded the highest sum of anions (CO₃^-2, HCO₃^-, Cl^-, and SO₄^-2) and cations (N⁺, P^+ 5, Ca^+ 2, Na⁺, K⁺, Fe^+ 2, and Mg^+ 2). In plants, the Djdi: CS3 treatment significantly enhanced the accumulation of N⁺, P^+ 5, K⁺, Ca^+ 2, and Fe^+ 2. Furthermore, Djdi: CS3 achieved the highest germination rates, mineral absorption, and growth parameters, alongside an increase in secondary metabolites (phenolics and flavonoids). Notably, stress biomarkers (MDA and H₂O₂) were significantly elevated in all Djdi-treated samples. RT-PCR analysis confirmed the up-regulation of key secondary metabolite genes, including chalcone synthase (CHS), phenylalanine ammonia-lyase (PAL), flavonol synthase (FLS), and chalcone isomerase (CHI), particularly in the Djdi: CS3 group.</p> Conclusion <p>The study concludes that the Djdi: CS3 (1:3) ratio serves as a novel, eco-friendly fertilizer that improves soil fertility, promotes plant growth, and boosts bioactive constituents. These findings align with Sustainable Development Goals (SDGs) by enhancing soil productivity for subsequent crop cycles.</p> Graphical Abstract <p></p>