PubMed · 2026-05-23
Researchers tested an ancient Egyptian mineral amendment called Djdi—a shale-based material used since Pharaonic times—as a soil additive for growing arugula. Blending Djdi with sandy clay soil in a 1:3 ratio boosted plant growth, nutrient uptake, and beneficial plant compounds compared to unamended soil.
A 1:3 Djdi-to-soil ratio produced the best results for arugula growth, nutrient uptake, and secondary metabolite (bioactive compound) production across all treatments tested.
XRD analysis identified Djdi as a sandy loam material rich in iron oxides and a mix of major and minor mineral oxides, explaining its soil-amendment potential.
The Djdi:CS2 and Djdi:CS3 treatments recorded the highest sum of soil anions, indicating improved soil chemistry and fertility compared to unamended sandy clay soil.
