In today’s world, when someone refers to fertilizing a garden, field, or lawn, the majority of people think of a bag of fertilizer with three numbers on it. The bag will likely have 10-10-10 or 10-13-13 or some combination of numbers. What do these numbers mean? They stand for the percentage of three macronutrients: N -Nitrogen, P-Phosphorus, and K-Potassium. So in a bag of 10-10-10, that means that in every 100 lbs of the material there will be 10 lbs of available Nitrogen, 10 lbs of Phosphorus, and 10 lbs of Potassium. The other 70 lbs of material are likely some form of inert material. N-P-K are three macronutrients that the average person knows about as fertilizer. The truth is that fertilizer is so much more than N-P-K alone.