Phosphorus (P) - The Plumeria Database

Phosphorus is a primary plant macronutrient, especially important for flower production. In fertilizer, usually expressed as phosphate.

Glossary: Fertilizer analysis
Fertilizer Basics
Manure and Compost as Nutrient Sources
Glossary: Macronutrients
From a management perspective only, the primary nutrients are N, P, and K, because they are most often limiting from a crop production standpoint. All of the other essential macronutrient elements are secondary nutrients because they are rarely limiting, and more rarely added to soils as fertilizers.
Macronutrients