Correct Option: A. Capillary water Explanation of the Correct Answer Capillary Water is the term used to describe the water that is held in the soil's micropores and is available for plants to absorb through their roots. This water is retained in the soil after excess water has drained away, and it is held against the force of gravity by surface tension. When soil reaches field capacity, it means that the soil has retained the maximum amount of water it can hold after gravitational water has drained away. At this point, the larger soil pores are empty, and the smaller pores are filled with water. This water is crucial for plant growth because it is accessible to plant roots. Why Capillary Water is Available for Root Absorption

1. Soil Structure: Soil is made up of various particle sizes (sand, silt, clay), which create spaces (pores) between them. Capillary water occupies these small pores.
2. Surface Tension: The water molecules adhere to the soil particles and to each other, creating a tension that allows the water to remain in the soil despite the pull of gravity.
3. Root Absorption: Plant roots can easily absorb capillary water because it is held in the soil at a tension that roots can exert enough force to overcome.

Why the Other Options are Incorrect B. Hygroscopic Water: - Hygroscopic water is the thin film of water that adheres tightly to soil particles. It is not available for plant uptake because it is held too tightly by the soil particles for roots to absorb it. Plants cannot access this water, making it unavailable for their needs. C. Gravitational Water: - Gravitational water is the excess water that drains through the soil due to gravity. This water is not retained in the soil and is not available for plant absorption once the soil reaches field capacity. It is the water that moves quickly through the soil profile and is lost to drainage. D. Superfluous Water: - Superfluous water refers to any excess water that is not needed by the soil or plants, often leading to waterlogging. Like gravitational water, it is not available for root absorption because it is in excess and can lead to detrimental conditions for plant growth. Summary of Key Points

• Capillary Water is the water available for plants at field capacity, held in micropores of the soil.
• Hygroscopic Water is tightly bound to soil particles and is unavailable for plant uptake.
• Gravitational Water drains away and is not retained in the soil, thus unavailable for plants.
• Superfluous Water is excess water that can lead to waterlogging and is also not available for absorption.

This understanding of soil water types is crucial for effective agricultural practices, as it helps in managing irrigation and ensuring optimal plant growth.