Question

Which of the following sphere is NOT associated with the soil?

• A. Ionosphere
• B. Atmosphere
• C. Lithosphere
• D. Hydrosphere

Hint:

Soil is a three-phase system (solid, liquid, gas) that represents the boundary zone where the lithosphere, atmosphere, hydrosphere, and biosphere meet.
High-altitude layers like the ionosphere have no direct connection to soil development.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Soil (comprising the pedosphere) is a dynamic, multi-phase system that exists at the interface of the major spheres of the Earth.
The physical, chemical, and biological properties of soil are determined by the interactions between these spheres.

Step 2: Detailed Explanation:
The pedosphere (soil) is formed and sustained through the intersection of four environmental spheres:
1. Lithosphere: The mineral phase of the soil, derived from the weathering of rocks and parent materials, which provides the physical framework and mineral nutrients.
2. Atmosphere: The gas phase, as soil pores are filled with soil air that facilitates gas exchange (such as oxygen for root respiration and carbon dioxide release).
3. Hydrosphere: The liquid phase, representing soil water held in pore spaces that acts as a solvent and transport medium for plant nutrients.
4. Biosphere: The organic and living phase, including plant roots, macro-organisms, and micro-organisms that drive organic matter decomposition and nutrient cycling.
The Ionosphere is a layer of the Earth's upper atmosphere, extending from about $60\text{ km to }1000\text{ km}$ above the surface, where solar radiation ionizes atmospheric gases.
The ionosphere is completely separate from the pedosphere and does not interact directly with soil processes.

Step 3: Final Answer:
The sphere not associated with the soil is the Ionosphere, which corresponds to Option (A).