The correct option is (c) 1 and 3 only.
Explanation
Soil acts as a habitat for various organisms by providing a porous structure that holds both water and air. The spaces (pores) between soil particles are crucial for maintaining the oxygen supply necessary for the survival of soil-dwelling fauna and flora.
Statement 1 is Correct:
Soil particles are not packed tightly into a solid mass; instead, they form aggregates with spaces or pores between them. These pores trap air from the atmosphere. Soil organisms, such as earthworms, nematodes, and plant roots, directly utilize this trapped air for respiration.
Statement 2 is Incorrect:
During heavy rains, water infiltrates the soil and fills the pore spaces, physically displacing the air that was previously trapped there. This results in a condition of waterlogging, which significantly decreases the availability of air (oxygen) in the soil. This oxygen deprivation is the primary reason why organisms like earthworms emerge to the surface during rains-to access atmospheric oxygen.
Statement 3 is Correct:
The majority of multicellular soil organisms (macrofauna and mesofauna) and plant roots are aerobic, meaning they require oxygen to break down glucose and generate energy. While anaerobic bacteria exist in soil, the general reference to "soil organisms" in this context implies those dependent on aerobic respiration.
Key Takeaway:
Soil aeration is inversely related to soil moisture saturation; heavy rainfall displaces soil air with water, creating hypoxic conditions that force aerobic soil organisms to seek oxygen elsewhere.