Multinutrient fertilizers Fertilizer

npk fertilizers three-component fertilizers providing nitrogen, phosphorus, , potassium.

npk rating rating system describing amount of nitrogen, phosphorus, , potassium in fertilizer. npk ratings consist of 3 numbers separated dashes (e.g., 10-10-10 or 16-4-8) describing chemical content of fertilizers. first number represents percentage of nitrogen in product; second number, p2o5; third, k2o. fertilizers not contain p2o5 or k2o, system conventional shorthand amount of phosphorus (p) or potassium (k) in fertilizer. 50-pound (23 kg) bag of fertilizer labeled 16-4-8 contains 8 lb (3.6 kg) of nitrogen (16% of 50 pounds), amount of phosphorus equivalent in 2 pounds of p2o5 (4% of 50 pounds), , 4 pounds of k2o (8% of 50 pounds). fertilizers labeled according n-p-k convention, although australian convention, following n-p-k-s system, adds fourth number sulfur, , uses elemental values values including p , k.