Which of the following statements about decomposition is incorrect?

Options

A. Decomposers break down complex organic matter into inorganic substances
B. Water insoluble organic nutrients go down into the soil horizon during the process of leaching
C. In fragmentation, detrivores break down detritus into smaller particles
D. Saprophytic bacteria and fungi secrete digestive enzymes over the fragmented detritus

Answer

To determine which statement about decomposition is incorrect, we will analyze the process of decomposition step by step.

### Step-by-Step Solution:

1. **Understanding Decomposition**:
- Decomposition is a biological process primarily carried out by organisms known as saprophytes, such as bacteria and fungi, which feed on decaying organic matter (detritus).

2. **Steps of Decomposition**:
- The process of decomposition consists of several steps:
- **Fragmentation**: This is the first step where detritus is broken down into smaller particles by organisms known as detrivores (e.g., earthworms).
- **Leaching**: In this step, water-soluble inorganic substances are washed down into the soil, where they can settle and contribute to the soil nutrient content.
- **Catabolism**: Here, the smaller particles are broken down further by enzymes secreted by bacteria and fungi.
- **Humification**: This is a longer process where the products of catabolism are converted into humus, a dark, organic substance that enriches the soil.
- **Mineralization**: Finally, humus is broken down into inorganic minerals that are available for plants.

3. **Analyzing the Statements**:
- Now, we will evaluate the statements provided in the question:
- **Statement 1**: Decomposers break down complex organic matter into inorganic substances. (Correct)
- **Statement 2**: Water insoluble organic nutrients go down into the soil horizon during the process of leaching. (Incorrect - it is water-soluble inorganic substances that leach into the soil.)
- **Statement 3**: In fragmentation, decomposers break down detritus into smaller particles. (Correct)
- **Statement 4**: Saprophytic bacteria and fungi secrete digestive enzymes over the fragmented detritus. (Correct)

4. **Conclusion**:
- The incorrect statement regarding decomposition is **Statement 2**, which claims that water insoluble organic nutrients go down into the soil during leaching.

### Final Answer:
The incorrect statement about decomposition is: **Water insoluble organic nutrients go down into the soil horizon during the process of leaching.**