Final answer:
A professional-use fertilizer's label includes a salt index indicating the potential for foliar burn; the higher this salt index, the greater the risk of burning plants. NPK rating describes the levels of nitrogen, phosphorus, and potassium in a fertilizer, indicated by a series of three numbers.
Step-by-step explanation:
The professional-use fertilizer states a salt index on its label that indicates the product's potential to cause foliar burn. The higher this number, the greater the burn potential. NPK fertilizers are examples of three-component fertilizers providing nitrogen, phosphorus, and potassium.
The NPK rating is a system describing the amount of nitrogen, phosphorus, and potassium in a fertilizer. It consists of three numbers separated by dashes, such as 10-10-10 or 16-4-8, and describes the chemical content of fertilizers. The first number represents the percentage of nitrogen, the second phosphorus (in the form of P2O5), and the third potassium (in the form of K2O).