The three numbers on fertilizer represents the value of the three macro-nutrients used by plants. These macro-nutrients are nitrogen (N), phosphorus (P) and potassium (K) or NPK for short. The higher the number, the more concentrated the nutrient is in the fertilizer.How do you calculate fertilizer?
How to Calculate Fertilizer Application. Divide the amount of nitrogen recommended per 1,000 square feet by the amount of nitrogen in the fertilizer mixture. For example, if the amount recommended is 3 pounds per 1,000 square feet and the amount of nitrogen in the fertilizer mixture is 21 percent, then divide 3 by .21 or 3/.21 = 14.28...What are the numbers on starter fertilizer?
Types of starter fertilizers and application rates. The three numbers on a fertilizer label indicate the percentages of nitrogen, phosphorus, and potassium (in that order) in the formulation.