Soil fertility. It is the ability of soil to provide good growth of plants. It is dependent upon pH value, size of soil particles, presence of minerals, presence of  air , optimum temperature etc.

Depletion of soil fertility is due to the following reasons :

1. Non-rotation of crops causes deficiency of minerals.

2. Precipitation of salts due to change of pH value.

3. Leaching of salts.

4. Over use of the land for cropping.

5. Over grazing.

7. Deforestation.