Soil microbial ecosystem scope: What does the “microbial ecosystem of soil” include when considered as a functional ecological unit?

Introduction / Context:
An ecosystem is defined by interactions between living organisms and their physical environment. Soil microbiology emphasizes this systems view to understand nutrient cycling, structure formation, and resilience.

Given Data / Assumptions:

• Soils contain diverse microbes plus meso/macrofauna and plant roots (rhizosphere).
• Abiotic matrices include minerals, pores, water films, gases, and humic substances.
• Processes emerge from interactions across components.

Concept / Approach:
The microbial ecosystem of soil is not just microbes in isolation; it is microbes embedded in and interacting with minerals, water, organic matter, and other organisms. Biogeochemical cycles, aggregate stability, and disease suppression arise from these coupled interactions.

Step-by-Step Solution:
Define ecosystem: biotic + abiotic + interactions. List soil biotic (microbes/fauna/roots) and abiotic (texture, moisture, nutrients) elements. Recognize that function depends on both sets. Choose the option that includes both components interacting.

Verification / Alternative check:
Models of carbon sequestration and nitrogen cycling require both biotic activity and abiotic sorption/mineral surface chemistry.

Why Other Options Are Wrong:
Biotic-only or abiotic-only perspectives are incomplete; “None” and microbe-only are incorrect by definition.

Common Pitfalls:
Overlooking the role of pore architecture and moisture dynamics in controlling microbial access to substrates.

Final Answer:
Both biotic and abiotic components of soil interacting together.