The first step in aggregate formation is

Correct option is C

The correct answer is (C) Flocculation

Explanation:
• Soil aggregation is the process by which individual soil particles (sand, silt, clay) are bound together into larger units called peds or aggregates.
• Flocculation is the first step in this process. It is a chemical/physical phenomenon where individual clay particles, which are negatively charged and repel each other, are brought together by cations (like $Ca^{2+}$ or $Mg^{2+}$) to form small clumps or "flocs."
• Once flocculated, these clumps must be stabilized by Cementation (the second step), where organic matter, iron/aluminum oxides, or microbial gums act as "glue" to hold the particles together permanently.
• Flocculation is necessary but not sufficient for stable aggregate formation; without cementation, the flocs would easily disperse when wet.

Information Booster:
• Multivalent cations (like $Ca^{2+}$) promote flocculation, whereas monovalent cations (like $Na^+$) promote dispersion.
• Soil structure is often referred to as the "architecture of the soil."
• Good aggregation improves porosity, aeration, and water infiltration.

Additional Knowledge:
• Dispersion (Option B): The opposite of flocculation; it is the breakdown of aggregates into individual particles, often caused by high sodium levels.
• Cementation (Option A): The process of hardening or binding the flocculated particles together.
• Compaction (Option D): The compression of soil, which usually destroys soil structure and reduces pore space.