PLSC204 Lecture Notes - Lecture 10: Permanent Wilting Point, Pressure Measurement, Water Potential
20 Jan 2019
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Document Summary
Tensiometer used to determine water potential in the field. Tube thats water filled, at top you have vacuum gauge and ceramic tip at the bottom, stick it in soil. The water in porous tip will be at a higher potential than the water in the dry soil, so the water will move be pulled and the vacuum gauge will be able to measure. Water tension is the same as water potential. Effective range is between . 0 and -85kpa. Different lengths of tensiometers can measure potentials at different depths. Relationship between water potential and pore size in soil. Pores larger than approx 10 to 30 m . Cannot hold water against the force of gravity (gravitational water vs capillary water) Associated potentials are approx -30 to -10kpa (pressure unit) Hold water too tightly for plants to use (plant unavailable capillary water) At beginning when soil begins to drain, the plant begins to transpire.
