Water retention curve

The water retention curve (WRC) is a fundamental concept in soil physics and hydrology that describes the relationship between the water content of a soil and the soil water potential. This curve is crucial for understanding the water-holding capacity of soils, which has significant implications for agriculture, irrigation, and environmental science.

Description

The water retention curve is typically plotted with the soil water potential (often expressed as matric potential) on the x-axis and the volumetric water content on the y-axis. The shape of the curve provides insights into the soil's ability to retain water at various tensions.

Key Parameters

Several key parameters are derived from the water retention curve:

• Field capacity - The amount of soil moisture or water content held in the soil after excess water has drained away and the rate of downward movement has decreased.
• Permanent wilting point - The minimal point of soil moisture the plant requires not to wilt.
• Available water capacity - The range of available water that can be stored in soil and be available for growing crops.

Measurement

The water retention curve can be determined using various laboratory and field methods. Common techniques include:

• Pressure plate apparatus
• Tensiometer
• Time domain reflectometry (TDR)

Applications

Understanding the water retention curve is essential for:

• Designing efficient irrigation systems
• Predicting soil erosion
• Managing soil salinity
• Enhancing crop yield

Factors Affecting the Water Retention Curve

Several factors influence the shape and position of the water retention curve, including:

• Soil texture
• Soil structure
• Organic matter content
• Bulk density

Related Pages

• Soil physics
• Soil water potential
• Matric potential
• Field capacity
• Permanent wilting point
• Available water capacity
• Pressure plate apparatus
• Tensiometer
• Time domain reflectometry
• Soil texture
• Soil structure
• Organic matter
• Bulk density

See Also

• Hydrology
• Agriculture
• Irrigation
• Environmental science

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