1. Types of Soil Moisture Figure 9.8 A block of soil is made up of three components, air, water, soil. The sum of the volume of air and water make up the total pore space in the soil. Volume Metric Soil Water = Vwater/(Vwater+Vair+Vsoil) Porosity=(Vwater+Vair)/(Vwater+Vair+Vsoil)

2. Soil-Moisture Availability Figure 9.9

3. Precipitation Measurement wind The eddies created by the rain gauge could deflect rain drop to fall into the rain gauge causing measurement error.

4. Precipitation Measurement A shielded rain gauge Note: Precipitation is highly uneven over space.

5. Evaporation Measurement An evaporation pan. How this measurement compare with the Potential Evapotranspiration, i.e. ET of the surrounding environment without moisture constraint?

6. Lysimeter and Weather Instruments Figure 9.7 Death Valley, CA Lysimeter is able to keep vegetation and soil in a relatively undisturbed condition.