Question

Why does soil lose its fertility from time to time?

Answer 1

Soil as such does not lose fertility just by growing crop but lose it fertility due to accumulation of unwanted and depletion of wanted inorganic salts from the soil by improper irrigation and acid rain water (quantity and quality of water)

Answer 2

Loss of plant nutrients (nitrogen, potassium, calcium, iron, etc.) or loss/gain of organic material due to growth of crops or soil erosion are reasons that soil loses its fertility.