The first step that must occur before plants can make use of nitrogen present in dead organic material is

Options

A. Ammonification
B. Nutrification
C. Denitrification
D. None

Answer

To solve the question, "The first step that must occur before plants can make use of nitrogen present in dead organic material is," we need to understand the nitrogen cycle and the processes involved. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Nitrogen Cycle
The nitrogen cycle consists of several processes that convert nitrogen from one form to another, making it available to plants and other organisms. The key processes involved are ammonification, nitrification, and denitrification.

### Step 2: Identify the Processes
- **Ammonification**: This is the process where organic nitrogen (from dead organisms or waste) is converted into ammonium (NH4+). This step is crucial because plants cannot use organic nitrogen directly.
- **Nitrification**: This process involves the conversion of ammonium into nitrites (NO2-) and then into nitrates (NO3-), which are forms that plants can absorb.
- **Denitrification**: This process converts nitrates back into nitrogen gas (N2), releasing it into the atmosphere.

### Step 3: Determine the First Step
Before plants can utilize nitrogen from dead organic material, the first step that must occur is **ammonification**. This process converts the organic nitrogen in dead material into ammonium, which is a form that plants can use.

### Step 4: Conclusion
The answer to the question is **ammonification**. This is the first step necessary for plants to access nitrogen from dead organic material.

### Final Answer:
**Ammonification**

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