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Transforming syenite through alkaline-hydrothermal processes: A sustainable strategy to overcome potassic fertilizer shortages in tropical regions

  • 0Geology & Sustainable Mining Institute (GSMI), Mohammed VI Polytechnic University, Lot 660, Hay Moulay Rachid, Benguerir 43150, Morocco; Institut de recherche en mines et en environnement, Université du Québec en Abitibi-Témiscamingue, 445 boulevard de l'Université, Rouyn-Noranda, Québec J9X 5E4, Canada.
The Science of the Total Environment +

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April 14, 2025

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April 14, 2025

View abstract on PubMed

Summary

This summary is machine-generated.

Alkaline hydrothermal treatment significantly enhances nutrient release from silicate rocks like syenite. This process improves potassium and multi-nutrient availability for soil health and crop productivity.

Area Of Science

  • Geochemistry and Soil Science
  • Materials Science
  • Mineralogy

Background

  • Silicate rocks are crucial for soil health and crop productivity, but their slow nutrient release limits agricultural potential.
  • Understanding nutrient release mechanisms from silicate minerals is key to developing sustainable soil amendments.
  • Alkaline hydrothermal treatment offers a potential method to accelerate nutrient availability from geological materials.

Purpose Of The Study

  • To evaluate the effect of alkaline hydrothermal treatment on potassium (K) and multi-nutrient (P, Ca, Mg, S, Si) availability from syenite rock.
  • To characterize the mineralogical, chemical, and structural changes induced by the treatment.
  • To investigate the nutrient release kinetics and identify factors influencing weathering.

Main Methods

  • Syenite rock was treated hydrothermally with CaO and KOH using a Design of Experiments (DOE) approach.
  • Characterization involved petrography, X-ray fluorescence (XRF), X-ray diffraction (XRD), QEMSCAN, EPMA, and FTIR.
  • Sequential leaching tests in deionized water followed by ICP-AES analysis quantified nutrient release.

Main Results

  • Hydrothermal treatment induced significant mineralogical, chemical, and structural alterations in syenite.
  • KOH-treated materials showed substantial potassium release (up to 1631 mg/L).
  • Treated samples released 3 to 69 times more nutrients than raw material, with slow but sustained dissolution rates.

Conclusions

  • Powdered syenite, after alkaline hydrothermal treatment, can serve as a valuable nutrient reservoir and soil buffer.
  • The treatment effectively enhances the availability of essential nutrients for agricultural applications.
  • Understanding rock weathering mechanisms through this treatment provides insights for soil amendment development.

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