N - P - K The code identifying the components in a fertilizer mixture : Nitrogen ( N ) , Phosphorus pentoxide ( P ; as P2O5 ) , and Potassium oxide ( K ; as K2O ) .
Fertilizers are graded in the order N - P - K , with the numbers indicating the percentage of the total weight of each component .
For example ,
45-0-0 represents a fertilizer containing by weight 45% nitrogen , 0% phosphorus pentoxide , and 0% potassium oxide
5-10-10 represents a fertilizer mixture containing by weight 5% nitrogen , 10% phosphorus pentoxide , and 10% potassium oxide