Fertilizing Properties of Potassium Feldspar Altered Hydrothermally

ABSTRACT

The material obtained through hydrothermal alteration of K-feldspar rock in alkaline conditions is a potential source of soluble potassium (K), but agronomic testing is needed to verify its capacity to supply K to crops. A (NH₄)₂SO₄-based bioassay was used to test the capacity of the material to supply K to tomato plants (Lycopersicon esculentum Mill.) growing in a mixture of silt loam, peat moss, and sand. Potassium chloride (KCl) and unaltered K-feldspar rock powder also were tested for comparison. The fresh weight and K composition of the plants increased as doses of KCl or hydrothermal material increased, but not with increases in K-feldspar rock. Development of stem lesions, which develop as symptoms of K deficiency in the presence of (NH₄)₂SO₄, were eliminated by KCl or hydrothermal material but not by feldspar rock. A beneficial effect may occur due to the calcium (Ca) supplied or with adjustment of soil acidity by the hydrothermal material. The hydrothermal material is a K fertilizer at least as effective as KCl since it yields the same or better plant weight.

KEYWORDS:

• Potassium chloride
• syenite
• tomato
• potassium fertilization
• calcium fertilization
• feldspar rock
• rock dust

Acknowledgments

The K-feldspar rock powder and the hydrothermal material tested in this study were provided by Advanced Potash Technologies, Woburn, MA.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by the The Abdul Latif Jameel World Water and Food Security Lab (J-WAFS) at MIT.

Notes on contributors

Davide Ciceri

Davide Ciceri is research scientist at the Massachusetts Institute of Technology. He received a B.Sc. and M.Sc. in Chemistry from The University of Milan and a Ph.D. in Chemical Engineering from the University of Melbourne. His research interests focus on hydrometallurgy and fertilizer materials.

Thomas C. Close

Thomas C. Close is a doctoral student in the Allanore and Hatton research groups at the Massachusetts Institute of Technology, working on the characterization of heterogeneous fertilizer materials. He has obtained a bachelor’s degree in Chemical Engineering from the Rochester Institute of Technology, where he performed research in the fields of sustainability and nanotechnology.

Allen V. Barker

Allen V. Barker is Professor of Plant and Soil Sciences at the University of Massachusetts. He teaches courses in organic farming, plant nutrition, and soil fertility. His research interests are in plant nutrition and soil fertility. He is a graduate of the University of Illinois, Urbana-Champaign with a BS degree and received MS and Ph D degrees from Cornell University.

Antoine Allanore

Antoine Allanore is Associate Professor in the Department of Materials Science & Engineering at the Massachusetts Institute of Technology, in Cambridge, MA. His research laboratory investigates sustainable materials and processes, and he teaches thermodynamic and chemical metallurgy at both the undergraduate and graduate level. His career began with several years of service to the materials processing industry.