1. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Chapter 5 Soil Water: Characteristics and Behavior Bringing water to arid valley soils. (R. Weil)

2. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Figure 5.1

3. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Water Properties Polarity – Charge difference across the water molecule Adhesion – Attraction of water molecules to solids Cohesion – Attraction of water molecules to themselves Surface Tension – Water’s attraction to itself results in a surface film

4. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Figure 5.2

5. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Figure 5.3 Surface Tension

6. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Figure 5.4

7. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Capillary Action Capillary Action – The water molecules are attracted to the sides of the solid and spread out in response to that attraction. Best observed when putting a thin glass tube in water.

8. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Figure 5.6 Capillary Action

9. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Figure 5.7 (a)(b)

10. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Soil Water Potential Soil Water Potential – The difference in energy levels between pure water in the reference state and soil water. –The difference in energy levels of water from one site or condition to another determines the direction and rate of water movement.

11. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Soil Water Potential –Gravitational Potential – The force of gravity acting on soil water attracts the water towards the center of the Earth –Submergence Potential – The positive hydrostatic pressure associated with the weight of water in a saturated soil –Matric Potential – The negative pressure due to the attractive force between water and the soil matrix –Osmotic Potential – The potential energy of water as it is reduced by the presence of solutes

12. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Figure 5.8

13. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Figure 5.9

14. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Figure 5.10

15. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Measuring Water Content Gravimetric Method – Taking a soil sample weighing, drying, then weighing the sample again to determine how much water was lost. Neutron Scattering – Fast neutrons are emitted into the soil. When they collide with a hydrogen atom the neutron slows down and is counted. Electromagnetic Method – Measures the reflection of electromagnetic signals by soil water.

16. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Figure 5.14 Neutron Moisture Meter

17. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Figure 5.15 Time Domain Reflectrometer (TDR)

18. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Measuring Soil Water Potential The tenacity with which water is held in the soils is an expression of soil water potential. Tensiometers – Measure the attraction of water in the soil column by adhesion and cohesion.

19. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Figure 5.16 Tensiometer

20. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Preferential Flow Preferential Flow – Water travels quickly down large soil pathways, such as connected macropores. –This leads to the quick disbursal of pesticides and other toxins into the soil and finally the groundwater.

21. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Infiltration and Percolation Infiltration – The process by which water enters the soil pore spaces and becomes soil water. Percolation – Once the water is in the soil, it moves through the soil column by percolation. Wetting Front – A sharp boundary demarcating the transport of water through the column

22. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Figure 5.26 Wetting Front 24 Hours After 5cm of Rainfall

23. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Figure 5.27 Water Infiltration

24. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Figure 5.29

25. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Soil Wetness Saturation – When all of the soil pores are filled with water. Field Capacity – Air instead of water occupies the macropores. Micropores and capillary pores are still filled with water. Wilting Point – The time at which plants have removed all of the water from the capillary pores and no more available water remains in the soil.

26. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Figure 5.32

27. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Figure 5.33

28. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil Cross-section of a Root Surrounded be Soil in Wet and Dry Conditions

29. ©2002 Pearson Education, Inc. Upper Saddle River, New Jersey 07458 THE NATURE AND PROPERTIES OF SOILS, 13/e Nyle C. Brady and Ray R. Weil