Which of the following soil properties is most directly influenced by microorganism activity?

• A. Soil texture
• B. Soil color
• C. Rock formation
• D. Nutrient cycling and availability

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the role of microorganisms in soil. Microorganisms such as bacteria and fungi are crucial in breaking down organic matter and recycling nutrients, which directly affects nutrient cycling and availability in the soil.
2. Step 2: Analyze each soil property listed: Soil texture refers to the proportion of sand, silt, and clay particles; Soil color is influenced by mineral content and organic matter; Rock formation is a geological process unrelated to microbial activity.
3. Step 3: Recognize that soil texture and rock formation are primarily physical and geological properties, respectively, and are not directly altered by microorganisms.
4. Step 4: Identify that nutrient cycling and availability depend on microbial processes like decomposition, nitrogen fixation, and mineralization, which transform nutrients into forms accessible to plants.
5. Step 5: Conclude that among the options, nutrient cycling and availability is the soil property most directly influenced by microorganism activity.