t7-1 soil science & management, 4e chapter 7 soil water
TRANSCRIPT
T7-1 Soil Science & Management, 4E
Chapter 7
Soil Water
T7-2 Soil Science & Management, 4E
Objectives
• 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
T7-3 Soil Science & Management, 4E
Terms to Know• 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
T7-4 Soil Science & Management, 4E
Terms to Know• Hygroscopic water• Matric potential• Osmotic potential• Permanent wilting
point• Potentiometer• Preferential flow• Resistance block• Saturated flow
• Saturation• Soil-moisture tension• Soil-potential• Temporary wilting
point• Unsaturated flow• Volumetric water
content• Water content
T7-5 Soil Science & Management, 4E
How Plants Use Water
• Effect of water stress
• Effect of excess water
T7-6 Soil Science & Management, 4E
Forces on Soil Water
Figure 7-2
T7-7 Soil Science & Management, 4E
Forces on Soil Water
• Capillarity
Figure 7-3
T7-8 Soil Science & Management, 4E
Forces on Soil Water
• Soil-water potential
Figure 7-4
T7-9 Soil Science & Management, 4E
Forces on Soil Water
Figure 7-5
T7-10 Soil Science & Management, 4E
Types of Soil Water
• Available water
Figure 7-6
T7-11 Soil Science & Management, 4E
Water Retention and Movement
• Water retention
Figure 7-8
T7-12 Soil Science & Management, 4E
• Water movement
Figure 7-9
Water Retention and Movement
T7-13 Soil Science & Management, 4E
• The wetting front• Capillary rise• Effect of soil horizons (See Figure 7-11)
• Preferential flow
Figure 7-11
Water Retention and Movement
T7-14 Soil Science & Management, 4E
How Roots Gather Water
Figure 7-12
T7-15 Soil Science & Management, 4E
How Roots Gather Water
• Pattern of water removal
Figure 7-13
T7-16 Soil Science & Management, 4E
Measuring Soil Water
• Gravimetric measurements– Weight basis– Soil depth basis
T7-17 Soil Science & Management, 4E
Measuring Soil Water
• Potentiometers
Figure 7-14
T7-18 Soil Science & Management, 4E
Measuring Soil Water
• Resistance blocks
• Neutron probe
Figure 7-17
T7-19 Soil Science & Management, 4E
Summary
• Not unlimited resource
• Conservation important
• Improve water-use efficiency
• Lower evapotranspiration
• Pay attention to possible pollution sources