Nitrogen ; Phosphorus; Potassium are mineral salts (Cations / Anions) they are required by a plant for growth. They are not vitamins, or organic. They do feed the plant so that proteins can be produced by the action of photosynthesis, etc.
there are soem 92 natural elements in the universe that all effect plant growth and development.
Before apply any 'Fertilisers' you need to know what is already in ther soil and its relationship with soil microbial, fungi, fauna life and so on.

Feeding a plant with Nitrate nitrogen may be required if applied in excess it will produce a weak straggly plant prone to disease and pest. nitrates are also carcinogens.

Please mail me / reply for more information and better soil health. Remember a plant will response to how we treat the soil. If we eat the produce from the plant then we too respond from the quality of the plant.
Ever wondered why there are so many sick people around?? You are what you eat. The plant is also what it eats (utilises)
Mark Atkins
Agronomist