Based on the sources nutrients can be classified in the following manner:

(i) Air: Some of the nutrients are directly obtained from the atmosphere or air present in the environment.

They are: Carbon dioxide, Oxygen and Hydrogen.

(ii) Water: Some of the nutrients are obtained from the water body in the surroundings or by watering the plants.

The nutrients that are obtained from water are: Nitrogen, Phosphorus, Calcium, etc.

(iii) Soil: Some of the nutrients are obtained from the soil in which the plant is present. Soil varies from place to place and hence the crop is grown depending on the type of soil.

The nutrients that are obtained from the soil are: Iron, Manganese, Sulphur, etc.