Current molten salt mixes are typically 60% sodium nitrate and 40% potassium nitrate.

FORBES: Secret Ingredient To Making Solar Energy Work: Salt

And David Laird, of America's Department of Agriculture, showed that biochar even helped the rich soil of America's Midwest by reducing the leaching from it of a number of nutrients, including nitrate, phosphate and potassium.

ECONOMIST: Biochar could enrich soils and cut greenhouse gases as well