A gardener often gently digs up the soil around the roots of garden plants or herbs for following reasons
(i) It enables easy root growth.
(ii) For easier percolation of water.
(iii) For aerating the soil enabling air to get into deeper layers of soil.
(iv) For removing the weeds.

Percolation property of any material is linked to its porosity. Different soils have different porosity. Therefore, water percolates differently through different soil.
Percolation rate of water in the soil = \(\frac { volume\quad of\quad water\quad percolated }{ time\quad taken\quad for\quad percolation } \)
Whereas water retaining capacity of a soil is described in terms of the amount of water absorbed by a particular type of soil. High water retaining capacity means higer water absorption.

Clayey soil is useful for the crops because
(i) it has good water retaining capacity.
(ii) it is rich in humus.
(iii) it is fertile in nature.
Crops like wheat and rice can be easily grown in clayey soil.

Differences between clayey soil and sandy soil are

Soil formation is a slow process which occurs in following two steps
(i) Weathering of rocks is the breakdown of rocks into small particles by the action of air, wind and water.
(ii) These small particles mix with humus (organic matter) and form soil.

The farmer can convert acidic soil into neutral soil by adding a small quantity of quicklime or slaked lime solution to the soil

The rotting dead matter in the soil is called humus.

Clayey soil and loamy soil are rich in humus and are suitable for growing plants like wheat and gram.

Weathering is a natural process by which huge rock is broken down into tiny particles but at a very slow rate.

Clayey soil absorbs more water but allows less water to percolate

(a) An earthworm helps in making the rich humus in soil.
(b) Ant, earthworm, termites, milipede, centipede, etc.
(c) Curiosity to learn and scientific attitude

Strong wind and rain can cause soil erosion from the barren land. This can be shown by performing an activity.
Take a wooden block and place some soil or sand on it. Keep an ice-cube tray at one end of the wooden black. Take a small battery-operated fan or hair dryer and hold it at the other end of the black near sand so that it blows the sand into the tray.
We will observe that when the fan blows it causes sand or soil particles to move and these get land in the various compartment of the ice-cube tray. This activity shows that the wind blows the soil on a barren land and may cause soil erosion.