Question

The clay soil holds more water than sandy soil. Why?

Answer 1

Hint: Soil is a material composed of ingredients such as minerals, soil organic matter, living organisms, gas, and water.
Soil minerals are divided into three size classes — clay, silt, and sand.

Complete answer: The soil's ability to retain water is strongly related to particle size.
Water molecules hold more tightly to the fine particles of a clay soil than to coarser particles of sandy soil, so clays generally hold more water. Sands provide easier passage or transmission of water through the profile. Clay has cohesive forces between them whereas sand does not have those cohesive forces,
Due to these voids are left in huge sizes in sand compared to clay.
Although the void ratio (actual void sizes) is more in clay but is small in size and not interconnected, so it prevents water from flowing through it. Sand on the other hand has more void sizes which are interconnected but overall, less void (actual spaces) and so water even if present in sand permeates through those interconnected voids. Thus, clay soil holds more water than sandy soil.

Additional Information: Soil has four important functions:
 1. It helps as a medium for plant growth.
 2. It functions as water storage, supply, and purification.
 3. It helps as a modifier of Earth's atmosphere.
 4. It acts as a habitat for organisms.

Note: Sand is a granular material composed of finely divided rock and mineral particles.
It is defined by size, being finer than gravel and coarser than silt.
Clay is a type of fine-grained natural soil material that contains hydrous aluminum phyllosilicates (clay minerals) that develops plasticity when wet.
Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure. Silt is granular material of a size between sand and clay, whose mineral origin is quartz, and feldspar. Soil science has two basic branches of study.
They are- edaphology and pedology.