In many parts of the country, gardeners can’t buy fertilizers that contain phosphorus unless they have soil test results that show the need for that middle number on the fertilizer bag. Nitrogen, phosphorus, and potassium are the three nutrients the percentage of each is listed in that order on every fertilizer package. Nitrogen and potassium are both relatively water soluble and seldom are found in soils in high levels. But phosphorus doesn’t move easily downward through the soil profile with rainfall or irrigation and can reach extremely high levels when gardeners don’t follow soil test recommendations. Your local Extension office may not be open to the public, but you can call them or Clemson’s Home and Garden Information Center for directions on how to submit a soil sample directly. Don’t waste money and risk excess nutrients harming rather than helping your plants.