The primary role of organisms in soil formation is that they supply material to the soil.

The primary role of organisms in soil formation is indeed to supply material to the soil. Here's a step-by-step explanation:

1. Organic Matter Addition: Organisms like plants and animals contribute organic matter to the soil. When these organisms die, their bodies decompose and become part of the soil. This organic matter is a key component of soil and contributes to its fertility.

2. Nutrient Cycling: Organisms in the soil, such as bacteria and fungi, help to break down organic matter and recycle nutrients. These nutrients are then available for plants to use.

3. Soil Structure Formation: Some organisms, like earthworms and ants, help to form the structure of the soil. They create tunnels and channels in the soil, which improves aeration and water movement.

4. Soil Stabilization: Certain organisms, like lichens and mosses, can help to stabilize the soil. They can bind soil particles together, preventing erosion and helping to maintain the soil structure.

5. Disease Suppression: Some soil organisms can suppress diseases. They do this by competing with or preying on disease-causing organisms.

In conclusion, organisms play a crucial role in soil formation by contributing organic matter, aiding in nutrient cycling, forming soil structure, stabilizing the soil, and suppressing diseases.