BOT 2100 Lecture Notes - Lecture 17: Semipermeable Membrane, Cell Membrane, Water Potential
Document Summary
Not all types of soil hold or transfer water in the same pattern or at the same speed. Wet soil: most of the space within soil particles is filled with water. Dry soil: most of the space within soil particles is filled with air. The ability of soil to hold water is dictated by countless factors, that add up to determine porosity. Soil particles can be 2-2,000 micrometers in diameter, and have an approximate surface to volume ratio of 10:1. Clay particles in the soil that have a negative charge (anions) can bind to positively charged ions (cations) in the soil, where root hairs interact. Root hairs constantly pump our protons that bind to the ion to create a positive charge, which allows them to be uptaken. This uses atp, as it is an active process. Depending on the composition, some soils can be highly acidic or very basic.
