con leary asked 12 years ago

Im doing agricultural science for the Leaving this year and for my project Im using potasium nitrate as my fertilizer. Im wondering where I can get it pure or almost pure or if there is a brand of it in garden centres.I have a fertilizer of NPK ratio 15-5-30. What percent potasium nitrate would that be?and would it be good for tomatoes.

1 Answers

Gerry Daly Staff answered 4 years ago
Potassium nitrate is also known as saltpetre and it is not sold pure as a fertilizer, but it would probably be available from companies that supply to school laboratories. It is a component in gun powder.

Potassium nitrate is KNO3, 38% potassium, 13%nitrogen, in NPK terms, 13-0-38.

Sulphate of potash (K2SO4) and muriate of potash, (KCl), are also used as sources of potassium fertilizer and nitrogen fertilizer.

Compound fertlizers, such as your 15-5-30, may contain any of these forms of potash.

15-5-30 would be fine for tomatoes as regards potash and nitrogen but potassium nitrate on its own would lack phosphorus, which is particularly important for root growth.