Process of intermixing of soil horizons by external factor is called

Correct option is D

The correct answer is (D) Pedoturbation

Explanation:
• Pedoturbation is the process of mixing soil constituents. This mixing prevents the development of distinct horizons or can destroy existing ones.
• It can be caused by various external factors: 1. Bioturbation (animals like earthworms or termites), 2. Cryoturbation (frost churning in cold climates), and 3. Argilliturbation (swelling and shrinking of clays like in Vertisols).
• It is a pedogenic process that works in opposition to horizonation (the formation of distinct layers).

Information Booster:
• Vertisols (Black soils) are famous for pedoturbation due to high montmorillonite clay content; they are often called "self-plowing" soils.
• Pedoturbation is important for incorporating organic matter into deeper layers and improving soil aeration.

Additional Knowledge:
• Argillation (Option A): Refers to the formation of clay minerals or the accumulation of clay in a specific horizon (illuviation).
• Horizonation (Option B): The process of differentiation of soil into distinct layers (O, A, E, B, C) through additions, losses, transfers, and transformations.
• Gleization (Option C): A process occurring in waterlogged (anaerobic) conditions leading to the reduction of iron and manganese, resulting in bluish-gray or mottled soil colors.