Formation of organic matter takes place by

Options

A. Chemical weathering
B. Soil micro-organisms
C. Herbivores
D. Soil water.

Answer

To answer the question "Formation of organic matter takes place by," we will analyze the options provided and understand the role of soil microorganisms in the formation of organic matter.

### Step-by-Step Solution:

1. **Understanding Organic Matter**: Organic matter refers to the material that is derived from living organisms, which includes plant and animal residues at various stages of decomposition.

2. **Decomposition Process**: Organic matter in the soil undergoes decomposition. This process is crucial as it transforms unstable organic material into a more stable form known as humus.

3. **Role of Microorganisms**: Microorganisms, including bacteria and fungi, play a vital role in the decomposition of organic matter. They break down complex organic materials into simpler substances, facilitating the formation of humus.

4. **Formation of Humus**: The decomposition carried out by microorganisms leads to the formation of humus, which is a resistant state of organic material. This humus is essential for soil fertility and provides nutrients to plants.

5. **Conclusion**: Among the options provided:
- Chemical weathering does not directly form organic matter.
- Soil microorganisms are responsible for the decomposition and formation of organic matter.
- Herbivores contribute to organic matter but do not directly form it.
- Soil water is essential for various processes but does not form organic matter by itself.

Thus, the correct answer is **soil microorganisms**.

### Final Answer:
**Formation of organic matter takes place by soil microorganisms.**

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