Introduction:
The type of soil that facilitates easy percolation of water is alluvial soil. Alluvial soil is formed by the deposition of sediments carried by rivers and streams. It is one of the most fertile types of soil found in various parts of the world, including the Indo-Gangetic plains in India.

Explanation:
Alluvial soil:
Alluvial soil is composed of a mixture of clay, silt, sand, and gravel. It is characterized by its fine texture and high fertility. Alluvial soil is formed by the continuous deposition of sediments carried by flowing water. As a result, it is rich in minerals and nutrients, making it highly suitable for agricultural activities.

Percolation of water:
Percolation refers to the process of water infiltrating or seeping into the soil. It plays a crucial role in maintaining the water table and replenishing groundwater. The ability of soil to facilitate easy percolation of water is determined by its porosity and permeability.

Porosity:
Porosity refers to the amount of empty space or voids present in the soil. Alluvial soil has a high porosity due to its fine texture and the presence of small particles. These empty spaces allow water to move freely through the soil, facilitating easy percolation.

Permeability:
Permeability refers to the ability of soil to transmit water. Alluvial soil has a high permeability, mainly due to the presence of larger particles such as sand and gravel. These particles create larger pore spaces, which allow water to flow more easily through the soil.

Benefits of easy percolation:
The easy percolation of water in alluvial soil offers several benefits, including:
1. Replenishes groundwater: Easy percolation helps to recharge groundwater reserves, ensuring a sustainable water supply for various purposes.
2. Prevents waterlogging: The ability of alluvial soil to drain excess water quickly prevents the water table from rising too high and causing waterlogging, which can be detrimental to plant growth.
3. Reduces erosion: Alluvial soil's ability to absorb and retain water reduces the erosion caused by surface runoff, preventing soil degradation and loss of fertility.

Conclusion:
Alluvial soil, with its high porosity and permeability, facilitates the easy percolation of water. This characteristic makes it highly suitable for agricultural activities as it ensures proper drainage, prevents waterlogging, and maintains a healthy water table.