What are the three main elements on which plant growth and development depend?

Nitrogen (N), Phosphorus (P) and Potassium(K). These are the most crucial elements however plants require many other elements to actively photosynthesis. These are calcium (Ca) magnesium (Mg) sulphur (S).

Plants also require what are know as trace or micro elements. The plants only require a small amount of the element but without it deficiencies will occur. Boron (B), Copper (Cu), Molybdenum (Mo), Manganese (Mm), Iron (Fe), Zinc (Zn) and Choride (Cl)