The key difference between soil air and atmospheric air is that soil air contains a higher content of carbon dioxide and a low concentration of oxygen, whereas atmospheric air contains a high content of oxygen and a low content of carbon dioxide.
We can categorize air as soil air and atmospheric air according to their composition and other factors. Soil air is the gaseous phase of the soil, while atmospheric air, or the atmosphere of the Earth, is commonly known as air, and it is the layer of gases that occurs around the Earth’s surface.
CONTENTS
1. Overview and Key Difference
2. What is Soil Air
3. What is Atmospheric Air
4. Soil Air vs Atmospheric Air in Tabular Form
5. Summary – Soil Air vs Atmospheric Air
What is Soil Air?
Soil air is the gaseous phase of the soil. This type of air plays an important role in plant growth. Also, soil air is useful for the activity of soil organisms. This air can be found filled in soil pores along with water. Therefore, there is a dynamic equilibrium between water and air content in the soil. Moreover, soil aeration is an important factor in the normal growth of plants.
Unlike atmospheric air, soil air contains more carbon dioxide and low content of oxygen. Additionally, the soil generally contains around 100% humidity unless it is very dry. The soil porosity determines the contents of carbon dioxide and oxygen. The water content in the soil and the biological demand for oxygen by plant roots and microorganisms are other factors that determine the soil air content.
In wet or compacted soil, the exchange of air between the soil and atmosphere is low. Then the oxygen concentration tends to decrease where the carbon dioxide content increases. Furthermore, a well-aerated soil has a high content of oxygen and moisture that can support the respiration of aerobic organisms such as aerobes. The condition of optimal microbial growth in the soil is considered as 50-60% water-filled pore space with 40-50% air-filled space. Further, the change in soil aeration can affect the microbial community.
What is Atmospheric Air?
Atmospheric air, or the atmosphere of Earth, is commonly known as air, and it is the layer of gases that occurs around the Earth’s surface. These gases are retained by the gravity of the Earth that makes the planetary atmosphere. This atmospheric air is important in protecting life on Earth by creating pressure. This allows the liquid water to exist on the surface of the Earth, thereby absorbing UV radiation that warms the surface through heat retention. It is also important in reducing temperature extremes between the day and the night.
Typically, atmospheric air has about 78% nitrogen, 20% oxygen, 0.93% argon, 0.04% carbon dioxide, and trace amounts of other gases by mole fraction. Moreover, the air contains some amount of water vapor. This amount is typically 1% at the sea level and 0.4% over the entire atmosphere.
The atmosphere shows stratification in which the air pressure and density generally decrease with the altitude in the atmosphere. However, temperature changes in the atmosphere can vary differently with the altitude. This may remain constant or increase with the altitude in some regions.
What is the Difference Between Soil Air and Atmospheric Air?
The key difference between soil air and atmospheric air is that soil air contains a higher content of carbon dioxide and a low concentration of oxygen, whereas atmospheric air contains a high content of oxygen and a low content of carbon dioxide. Moreover, soil air occurs in the soil pores, while atmospheric air occurs above the surface of Earth.
Below is a summary of the difference between soil air and atmospheric air in tabular form for side-by-side comparison.
Summary – Soil Air vs Atmospheric Air
Air is essential for life on Earth. Air can occur in different forms according to the occurrence, composition, and other factors. Soil air and atmospheric air are two such types of air. The key difference between soil air and atmospheric air is that soil air contains a higher content of carbon dioxide and a low concentration of oxygen, whereas atmospheric air contains a high content of oxygen and a low content of carbon dioxide.
Reference:
1. “Soil Air: Composition and Factors: Soil Science.” Soil Management India, 22 Mar. 2018.
Image Courtesy:
1. “Oxigen cycle 1” By Eme Chicano – Own work (CC0) via Commons Wikimedia
2. “Composition of the atmosphere” (CC0) via Free SVG