Npk compound chemical fertilizer refers to nitrogen, phosphorus, potassium three nutrients, which marks at least two kinds of nutrients on the amount,and be made by chemical methods and (or) made of physical processing.Such as N-P2O5-K2O=12 12 17, 16 20 0,etc. Materials are from urea, ammonium phosphate, potash etc., plus Ca, Mg, S and other trace elements.