Question

why does it take so many years in formation of soil

Answer 1

The time needed to form a soil depends on the latitude:

in environments characterized by a mild climate, it takes 200-400 years to form 1 cm of soil

in wet tropical areas soil formation is faster, as it takes 200 years

in order to accumulate enough substances to make a soil fertile it takes 3000 years.

For these reasons the soil is considered as a non-renewable resource: once it has been destroyed, it is lost forever.