Soils of which textured class have minimum water holding capacity?

Correct option is A

The correct answer is (A) Sandy soil

Explanation:
• Water Holding Capacity (WHC) is primarily determined by the size of soil particles and the resulting pore spaces.
• Sandy soils are dominated by large particles (0.05 to 2.0 mm) and large "macropores." While these pores allow for rapid drainage and aeration, they have very little surface area to hold onto water through adhesion and cohesion.
• Because the pores are large, gravity easily pulls water down and out of the root zone, leaving sandy soils with the minimum WHC among all textural classes.
• In contrast, clay particles are very small and have a massive total surface area, allowing them to hold a large volume of water in "micropores."

Information Booster:
• Specific surface area: Sand has about $30 cm^2/g$, while Clay can have up to $8,000,000 cm^2/g$.
• Loam soils are considered ideal for agriculture because they provide a balance of macropores (for air) and micropores (for water).
• Adding organic matter is the best way to increase the WHC of sandy soils.

Additional Knowledge:
• Clay soil (Option B): Has the maximum total water holding capacity but may hold water so tightly that it is unavailable to plants (high wilting point).
• Loam soil (Option C): A medium-textured soil with moderate WHC and high "available" water capacity.
• Clay loam (Option D): A heavy-textured soil with high WHC, though slightly less than pure clay.