Transcript Chapter 7 Soil Water Soil Science & Management, 4E T7-1

Chapter 7
Soil Water
T7-1
Soil Science & Management, 4E
Objectives
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Identify the role of water in plant growth
Define the forces that act of soil water
Classify types of soil water
Discuss how water moves in the soil
Explain how plant roots remove water from
the soil
• Describe how to measure soil water
content
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Soil Science & Management, 4E
Terms to Know
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Adhesion
Adhesion water
Anaerobic
Available water
Bar
Capillary
Capillary rise
Capillary water
Cohesion
• Cohesion water
• Field capacity
• Gravimetric water
content
• Gravitational flow
• Gravitational potential
• Gravitational water
• Hydrogen bond
Soil Science & Management, 4E
Terms to Know
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Hygroscopic water
Matric potential
Osmotic potential
Permanent wilting
point
Potentiometer
Preferential flow
Resistance block
Saturated flow
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Saturation
Soil-moisture tension
Soil-potential
Temporary wilting
point
• Unsaturated flow
• Volumetric water
content
• Water content
Soil Science & Management, 4E
How Plants Use Water
• Effect of water stress
• Effect of excess water
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Soil Science & Management, 4E
Forces on Soil Water
Figure 7-2
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Soil Science & Management, 4E
Forces on Soil Water
• Capillarity
Figure 7-3
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Soil Science & Management, 4E
Forces on Soil Water
• Soil-water potential
Figure 7-4
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Soil Science & Management, 4E
Forces on Soil Water
Figure 7-5
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Soil Science & Management, 4E
Types of Soil Water
• Available water
Figure 7-6
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Soil Science & Management, 4E
Water Retention
and Movement
• Water retention
Figure 7-8
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Soil Science & Management, 4E
Water Retention
and Movement
• Water movement
Figure 7-9
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Soil Science & Management, 4E
Water Retention
and Movement
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The wetting front
Capillary rise
Effect of soil horizons (See Figure 7-11)
Preferential flow
Figure 7-11
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Soil Science & Management, 4E
How Roots Gather Water
Figure 7-12
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Soil Science & Management, 4E
How Roots Gather Water
• Pattern of water removal
Figure 7-13
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Soil Science & Management, 4E
Measuring Soil Water
• Gravimetric measurements
– Weight basis
– Soil depth basis
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Soil Science & Management, 4E
Measuring Soil Water
• Potentiometers
Figure 7-14
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Soil Science & Management, 4E
Measuring Soil Water
• Resistance blocks
• Neutron probe
Figure 7-17
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Soil Science & Management, 4E
Summary
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Not unlimited resource
Conservation important
Improve water-use efficiency
Lower evapotranspiration
Pay attention to possible pollution sources
Soil Science & Management, 4E