Source of Nutrients: Among all the nutrients the plants from atmosphere absorb only Carbon and Oxygen. Other elements are absorbed from the soil by root. These elements are present in the soil as different salts, but the plant cannot intake them directly They absorb as different ions.
The action of different mineral nutrients in plant nutrition: Actions of different elements are very acute in plant nutrition. For these elements are termed as essential elements. Formation of chlorophyll is hampered by the deficiency of Nitrogen. If chlorophyll is not formed manufacturing of food is hampered. If the manufacture of food is seized it hampered the process of respiration and causes less production of energy. Magnesium is one of the elements of chlorophyll. As a result of the deficiency of it will seize the formation of chlorophyll and manufacture of food by photosynthesis.
Potassium acts as a catalyst in many biochemical reactions in plants, for this, it is necessary for plant nutrition. The development of the plant by cell division is also control by potassium. So without it, plant nutrition is not at all possible.
We use Nitrogen (Urea), Potash (Murrate of Potash), Phosphorus (Triple supper Phosphate) ect. for crops as it played the valuable role in nutrition.