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Supplying three nutrient elements
Fertilisers supply compounds containing elements needed by plants. NPK fertilisers contain compounds of nitrogen, phosphorus and potassium and can improve agricultural productivity when used appropriately. They are formulations: mixtures designed to have suitable proportions of ingredients for a purpose. Different crops and soils can need different proportions. The letters refer to elements supplied in compounds, not to a bag containing free nitrogen, phosphorus and potassium elements.
