Question

If soil have all nutrients, then why do we need to replenish it.
Urgent!!!

Answer 1

because when we griw theplants over there all the nutrition will be already consumed so, we need to replenish it time to time.

Answer 2

This is due to several reasons:

(1) Nutrient uptake by plants

Plants take up several mineral ions such as nitrates(for general growth), phosphates (for root growth), magnesium (for chlorophyll).

In order for the plant to keep growing healthily, the soil has to be constantly replenished to supply them with the mineral ions required.

(2) Soil erosion/Percolation

Heavy precipitation, can result in the washing away of nutrients via percolation.