Petrography of the Altered Basaltic Rocks and their Evaluation as a Media for Plant Growth and Enrich Nutrients in Rhizosphere

Abstract

This study investigates the potential of altered basaltic rocks as a source of a sustainable soil amendment (media) for enhancing plant growth and soil quality in arid and semi-arid regions, particularly the sandy soils of Wadi El-Natrun, Egypt. The basaltic material was collected from El-Haddadin area near El Sheikh Zayed, Greater Cairo on area geologically part of the Tertiary volcanic episodes in Egypt. Based on the integrated petrographic investigation using the thin section microscopic examination and X-ray diffraction analysis, the composite sample of El- Haddadin area is heterogonous amygdaloidal glassy display significant alteration marked by calcite, smectite, illite, and celadonite minerals. The dominant amygdaloidal texture, variolitic groundmass, and calcite and smectite filling alteration products may contribute potential pedogenic implications. The rock was manually processed and mixed with the Wadi
Natrun sandy soil in varying proportions. A greenhouse experiment was conducted using Basil (Ocimum basilicum) as a test crop to evaluate the agronomic benefits of basalt-amended soil. The results showed that the mixture of 75:25 sand: basalt ratio significantly improved plant morphological traits (leaf area, root length, biomass fresh and dry weights), outperforming either sand or basalt media. Biochemical analyses revealed substantial increases in the concentration of essential nutrients (phosphorus, potassium, zinc, manganese, and iron) in plant tissues. Moreover, total flavonoid content was significantly enhanced with the mixture of 75:25 sand: basalt ratio. Textural features such as amygdaloidal structures, variolitic groundmass, and calcite-filled vugs reveal alteration processes
improved the pedogenic properties. It might be concluded that basalt amendments (media) represent a cost-effective and environmentally friendly practice to improve crop productivity and soil fertility in arid and semi-arid ecosystems. Further research for its long-term impacts and synergistic interactions with other soil- nano-technologies are recommended.