1. WATER I: POROSITY Intraped micropores Macropores

2. DENSITY AND WEIGHT Particle density: average density of the soil particles (mass per unit volume of soil solids) Bulk density: density of the bulk soil in its natural state, including particles and pore space Common minerals: Feldspars: 2.56 g cm -3 to 2.76 g cm -3 Quartz: 2.65 g cm -3

3. DENSITY AND WEIGHT d = 4.4 cm h = 5.0 cm w = 87.8 g Vol = 76.04 cm 3 W= 87.8 g  B = 1.15 g cm -3

4. “Light” versus “heavy” soils?

5. Porosity DbDpDbDp = = 0.438 = % solid  1 – 0.438 = 56.2 % (= porosity)  loamy sands 1.7 g cm -3 = 1.16 2.65 POROSITY

7. SOIL WATER  Adhesion  Cohesion

8. SOIL WATER

9. SOIL WATER POTENTIAL  Total soil water potential =  t  t =  g +  m  g = gh

10. SOIL WATER POTENTIAL  Matric potential =  m

11. SOIL WATER POTENTIAL Increasing water content Water potential 0-33 kPa-1500 kPa -3100 kPa -100 MPa -1000 MPa Oven-dry Air-dry Hygroscopic PWPFCSaturation UnavailablePlant-available water Gravitational water-drainable Water remaining in soil pores after wetting and drainage DRY MOIST (SEASONAL) SAT

12. WATER CHARACTERISTIC CURVES

13. WATER CHARACTERISTIC CURVES

14. MEASURING SOIL WATER  Volumetric water content  = m 3 of H 2 O/m 3 soil = depth of H 2 O/depth of soil = 0.1 m 3 of H 2 O/m 3 soil (10%) = 0.1 m of H 2 0/m of soil depth  m = g H 2 O/100 g dry soil

15. METHODS  Gravimetric 100 g sample (moist) 70 g (dry)  30 g H 2 O (or 30 kg/70 kg dry soil = 0.428)  = we must determine D b = 1.3 Mg/m 3  1 m 3 has 1300 kg of soil x 0.428 = 556 kg

16. METHODS Since 1 m 3 of water = mass of 1000 kg 556 kg water occupies 0.556 m 3  1300 kg soil m 3 H 2 O 0.428 kg H 2 O 0.556 m 3 H 2 O m 3 soil 1000 kg H 2 O kg soil m 3 soil  = D b x  m * * =

17. METHODS  Tensiometer