Question

Which soil has more pore space?

• A. Sandy soil
• B. Clay soil
• C. Sandy loam soil
• D. Silty soil

Hint:

Do not confuse "pore size" with "total pore space." Sandy soils have larger pores (macropores) but less total pore space. Clay soils have tiny pores (micropores) but a much higher total pore volume.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Soil porosity (total pore space) refers to the volume of soil occupied by air and water.
It depends heavily on soil texture and structure.
While individual pore sizes differ between sandy and clayey soils, the total percentage of pore space varies inversely with particle size.

Step 2: Detailed Explanation:
Let us compare the pore characteristics of sandy and clayey soils:
Sandy Soils (A): These soils are dominated by large, individual sand particles.
They have large, continuous pores (macropores) that allow rapid drainage and aeration.
However, because the particles pack together tightly without aggregate structures, the total pore space is relatively low, typically ranging from $35\%$ to $45\%$.
Clay Soils (B): These soils are composed of extremely small, platy clay particles.
These particles form complex, aggregated structures with a vast number of microscopic spaces (micropores).
Although these micropores are small and hold water tightly, their sheer number results in a much higher total pore volume.
The total pore space in clay soils typically ranges from $50\%$ to $60\%$.
Therefore, clay soil has more total pore space than sandy, sandy loam, or silty soils.

Step 3: Final Answer:
Clay soil contains the highest percentage of total pore space, which corresponds to option (B).