Water tightly held to soil particles all of the above

Options

A. Bound water
B. Hygrosopic water
C. Runaway water
D. all of the above

Answer

**Step-by-Step Solution:**

1. **Understanding Soil Water Types**: Water in the soil can be classified into different types based on its availability to plants. The main types include hygroscopic water, bound water, runaway water, and gravitational water.

2. **Identifying Hygroscopic Water**: Hygroscopic water is the water that is tightly held to soil particles. It is adsorbed onto the surface of soil colloids and is not available for plant uptake. This water is held very firmly and cannot be used by plants.

3. **Examining Other Water Types**:
- **Bound Water**: This type of water is chemically bound to soil particles, such as in the case of calcium sulfate, which has water molecules associated with it. Like hygroscopic water, bound water is also unavailable for plants.
- **Runaway Water**: This water is not retained in the soil; it has been washed away and does not remain in the field. Therefore, it is not held tightly to soil particles.
- **Gravitational Water**: This water drains through the soil due to gravity and is available for plants, but it is not tightly held.

4. **Conclusion**: Among the options provided, hygroscopic water is the type that is tightly held to soil particles and is unavailable for plant use. Therefore, the correct answer to the question is hygroscopic water.

5. **Final Answer**: The water tightly held to soil particles is **hygroscopic water**.

---