Name an artificial fertiliser or fertilisers which farmers can use to increase the supply of nitrate, phosphate and potassium to their crops.
NPK compound fertiliser having nitrogen (N) as nitrate, phosphorus (P) as phosphate and potassium (K) in suitable proportions. Alternatively, ammonium nitrate (NH4NO3) might be used as a source of nitrogen, and superphosphates as a source of phosphorus.