Sodium Nitrate — Frequently Asked Questions

On sodic or poorly drained soils, where accumulating sodium degrades soil structure by dispersing clay particles, and in recirculating hydroponic systems, where sodium builds up to toxicity because plants do not remove it at the rate it is applied. Potassium or calcium nitrate is the appropriate substitute in both cases.

Naturally occurring sodium nitrate from the caliche deposits of the Atacama desert, which was the world's principal source of fixed nitrogen for both fertiliser and explosives until the Haber-Bosch process made synthetic ammonia available in the early twentieth century. The deposits are still mined, though synthetic material now dominates.

Immediately. All its nitrogen is in nitrate form, which plants take up directly without the nitrification step that ammonium and urea require. That makes it fast-acting and useful for rapid correction, but also readily leached from the root zone by rainfall or irrigation, so it suits in-season correction better than season-long supply.

A molten mixture of sodium and potassium nitrate, typically around 60:40, used as a heat transfer and thermal storage medium in concentrated solar power plants. It remains liquid over a wide temperature range and is thermally stable, which allows heat collected during the day to be stored and used to generate electricity after dark.