NPK fertiliser

NPK stands for nitrogen, phosphorus and potassium: an NPK fertiliser contains compounds supplying all three elements. Plants take up nutrients through their roots as dissolved ions, so the chemical form of an element matters as well as its presence. An NPK fertiliser is a formulation—a mixture of salts chosen to provide suitable percentages of the three elements—not a single compound with the formula “NPK”.

An NPK fertiliser contains compounds supplying all three elements, while another fertiliser might supply only one or two of them.

An NPK fertiliser supplies compounds containing all three; the letters name the elements, not three separate pieces of metal.

An NPK fertiliser contains compounds that supply all three of the main nutrient elements. Different crops and soils do not always need the same proportions, so fertilisers can be formulated with different balances of N, P and K. For example, soil testing may reveal that one nutrient has been depleted more than the others.