SOIL 3600 Lecture Notes - Lecture 16: Gravitational Potential, Yorkshire Carnegie, Plasmolysis
13 Dec 2017
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Form hydration shells around dissolved ions: amount of osmotic potential depends on concentration of ions, greater concentration, greater the attraction. Ions try to keep the water around them to form hydration shell: by keeping close - does not affect mass flow, but affects water availability to the plant roots, why, cells are living things - membranes semi-permeable. If plant has higher concentration of ions inside the cell than outside = attract water: osmosis vs. plasmolysis. Total suction = -osmotic suction - matric suction - gravitational suction: equal and opposite. I. e. , soil suction = osmotic suction + matric suction + gravitational suction. H2o movement in soil (summary: heavy rain, fall from sky - Some infiltrate (enter the soil) ( high potential = low suction) (e. g. , -0. 01 mpa wettest: enter soil until top soil saturated. Saturated soil will drain fast: gravity acting on soil water in very large pores, as water moves due to gravity: comes a stage where it is not.
