The principa cation in alkaline soil is

Options

A. `Na^(+)`
B. `K^(+)`
C. `Ca^(+2)`
D. `H^(+)`

Answer

### Step-by-Step Solution:

1. **Understanding Alkaline Soil**:
- Alkaline soil is characterized by a high pH level, typically greater than 8.5. This means that the soil is less acidic and more basic.

2. **Characteristics of Alkaline Soil**:
- Alkaline soils often have a poor soil structure, which can affect plant growth.
- They also have low infiltration capacity, meaning they do not absorb water well.

3. **Identifying Principal Cations**:
- In alkaline soils, the principal cations are those that are abundant due to the soil's composition and parent material.
- The primary cation found in alkaline soils is Calcium (Ca²⁺).

4. **Reason for Calcium Dominance**:
- Alkaline soils are typically formed from parent material that is rich in calcium carbonate (CaCO₃). This is particularly common in arid or dry environments where weathering processes lead to the accumulation of calcium carbonate.

5. **Conclusion**:
- Based on the characteristics and composition of alkaline soils, the principal cation is Calcium (Ca²⁺). Therefore, the answer to the question is Calcium ion.