Plants utilize the mineral nutrients, especially nitrogen present in the soil, for their growth.
As a result there is a depletion of nitrogen in the soil over a period of time.
So, the farmers use manure and they spread it in their fields.
Manure contains a lot of nitrogen apart from potassium and phosphorus.

Why replenishment of soil is necessary?

Experiments/activities

EXPERIMENTS/ACTIVITIES

(1) An Experiment to Show That Only Green Plants Can Photosynthesise:

Requirements:

A Coleus leaf (variegated- leaf with two colours), beaker, beaker stand, Bunsen burner, water, test tube, ethanol, and iodine solution

Procedure: